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for-loop doc iterate
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John Kerl
parent
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commit
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11 changed files with 195 additions and 204 deletions
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@ -744,7 +744,18 @@ as the expression is parsed, before any input records are ingested.
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POKI_INCLUDE_AND_RUN_ESCAPED(data/single-for-example-1.sh)HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/single-for-example-2.sh)HERE
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<h3>For-loop over the current stream record</h3>
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<p/>Note that the value corresponding to a given key may be gotten as through a
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<b>computed field name</b> using square brackets as in <tt>$[key]</tt> for
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stream records, or by indexing the looped-over variable using square brackets.
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<h3>Key-value for-loops </h3>
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<p/>Single-level keys may be gotten at using either <tt>for(k,v)</tt> or
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<tt>for((k),v)</tt>; multi-level keys may be gotten at using
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<tt>for((k1,k2,k3),v)</tt> and so on. The <tt>v</tt> variable will be bound to
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to a scalar value (a string or a number) if the map stops at that level, or to
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a map-valued variable if the map goes deeper. If the map isn’t deep
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enough then the loop body won’t be executed.
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POKI_RUN_COMMAND{{cat data/for-srec-example.tbl}}HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-srec-example-1.sh)HERE
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@ -762,23 +773,20 @@ itself</b>:
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-srec-example-2.sh)HERE
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It can be confusing to modify the stream record while iterating over a copy of it, so
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instead you might find it simpler to use an out-of-stream variable in the loop and only update
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instead you might find it simpler to use a local variable in the loop and only update
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the stream record after the loop:
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-srec-example-3.sh)HERE
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<h3>For-loop over out-of-stream variable</h3>
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<p/> This is similar to looping over the current stream record except for
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additional degrees of freedom: you can start iterating on sub-hashmaps of an
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out-of-stream variable; you can loop over nested keys; you can loop over all
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out-of-stream variables. As with for-loops over stream records, the bound
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variables are bound to a copy of the sub-hashmap as it was before the loop
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started. The sub-hashmap is specified by square-bracketed indices after
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<tt>in</tt>, and additional deeper indices are bound to loop key-variables. The
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terminal values are bound to the loop value-variable whenever the keys are not
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too shallow. The value-variable may refer to a terminal (string, number) or it
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may be map-valued if the map goes deeper. Example indexing is as follows:
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<p/>You can also start iterating on sub-hashmaps of an out-of-stream or local
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variable; you can loop over nested keys; you can loop over all out-of-stream
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variables. The bound variables are bound to a copy of the sub-hashmap as it
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was before the loop started. The sub-hashmap is specified by square-bracketed
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indices after <tt>in</tt>, and additional deeper indices are bound to loop
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key-variables. The terminal values are bound to the loop value-variable
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whenever the keys are not too shallow. The value-variable may refer to a
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terminal (string, number) or it may be map-valued if the map goes deeper.
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Example indexing is as follows:
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POKI_INCLUDE_ESCAPED(data/for-oosvar-example-0a.txt)HERE
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@ -787,38 +795,44 @@ Suppose the out-of-stream variable <tt>@myvar</tt> is populated as follows:
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0b.sh)HERE
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<p/> Then the too-shallow parts — indexed by the basename <tt>myvar</tt>
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and the index <tt>"nesting-is-too-shallow"</tt> — have depth two
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(basename and one index specify a terminal value) and can be gotten as follows:
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<p/> Then we can get at various values as follows:
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<table><tr><td>
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0c.sh)HERE
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</td><td>
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0d.sh)HERE
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<p/>The <tt>"just-right"</tt> parts have depth three (basename and two indices
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specify a terminal value) and can be gotten at by any of the following:
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</td><td>
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0e.sh)HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0f.sh)HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/for-oosvar-example-0g.sh)HERE
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</td></tr></table>
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<h3>C-style triple-for loops</h3>
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<p/> These are supported as follows:
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POKI_INCLUDE_AND_RUN_ESCAPED(data/triple-for-example.sh)HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/triple-for-example-1.sh)HERE
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POKI_INCLUDE_AND_RUN_ESCAPED(data/triple-for-example-2.sh)HERE
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Notes:
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<ul>
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<li/> In <tt>for (start; continuation; update) { body }</tt>, the start,
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continuation, and update statements may be empty, single statements, or
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multiple comma-separated statements. If the continuation is empty it defaults
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multiple comma-separated statements. If the continuation is empty (e.g. <tt>for(i=1;;i+=1)</tt>) it defaults
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to true.
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<li/> In particular, you may use <tt>$</tt>-variables and/or
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<tt>@</tt>-variables in the start, continuation, and/or update steps (as well
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as the body, of course).
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<li/> The typedecls such as <tt>int</tt> or <tt>num</tt> are optional. If a
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typedecl is provided (for a local variable), it binds a variable scoped to the
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for-loop regardless of whether a same-name variable is present in outer scope.
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If a typedecl is not provided, then the variable is scoped to the for-loop if
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no same-name variable is present in outer scope, or if a same-name variable is
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present in outer scope then it is modified.
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<li/> Miller has no <tt>++</tt> or <tt>--</tt> operators.
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<li/> As with all for/if/while statements in Miller, the curly braces are
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required even if the body is a single statement, or empty.
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@ -1,11 +1,10 @@
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mlr --opprint --from data/small head -n 2 then put -q '
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mlr -n put --jknquoteint -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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}
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end {
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dump
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@myvar = {
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1: 2,
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3: { 4 : 5 },
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6: { 7: { 8: 9 } }
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}
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}
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end { dump }
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'
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@ -1,14 +1,16 @@
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mlr --from data/small head -n 2 then put -q '
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mlr -n put --jknquoteint -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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@myvar = {
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1: 2,
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3: { 4 : 5 },
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6: { 7: { 8: 9 } }
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}
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}
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end {
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for (k, v in @myvar) {
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@terminal[k] = v
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print
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"key=" . k .
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",valuetype=" . typeof(v);
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}
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emit @terminal, "index1"
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}
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'
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@ -1,14 +1,17 @@
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mlr --from data/small head -n 2 then put -q '
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mlr -n put --jknquoteint -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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@myvar = {
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1: 2,
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3: { 4 : 5 },
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6: { 7: { 8: 9 } }
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}
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}
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end {
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for ((k1, k2), v in @*) {
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@terminal[k1][k2] = v
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for ((k1, k2), v in @myvar) {
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print
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"key1=" . k1 .
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",key2=" . k2 .
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",valuetype=" . typeof(v);
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}
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emit @terminal, "basename", "index1"
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}
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'
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@ -1,14 +1,17 @@
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mlr --from data/small head -n 2 then put -q '
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mlr -n put --jknquoteint -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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@myvar = {
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1: 2,
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3: { 4 : 5 },
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6: { 7: { 8: 9 } }
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}
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}
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end {
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for ((k1), v in @myvar["nesting-is"]) {
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@terminal[k1] = v
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for ((k1, k2), v in @myvar[6]) {
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print
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"key1=" . k1 .
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",key2=" . k2 .
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",valuetype=" . typeof(v);
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}
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emit @terminal, "index1"
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}
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'
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@ -1,14 +0,0 @@
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mlr --from data/small head -n 2 then put -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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}
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end {
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for ((k1, k2), v in @myvar) {
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@terminal[k1][k2] = v
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}
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emit @terminal, "index1", "index2"
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}
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'
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@ -1,14 +0,0 @@
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mlr --from data/small head -n 2 then put -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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}
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end {
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for ((k1, k2, k3), v in @*) {
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@terminal[k1][k2][k3] = v
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}
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emit @terminal, "basename", "index1", "index2"
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}
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'
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@ -1,9 +1,9 @@
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mlr --from data/small --opprint put '
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@sum = 0;
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sum = 0;
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for (k,v in $*) {
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if (is_numeric(v)) {
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@sum += $[k];
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sum += $[k];
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}
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}
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$sum = @sum
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$sum = sum
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'
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7
doc/data/triple-for-example-1.sh
Normal file
7
doc/data/triple-for-example-1.sh
Normal file
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@ -0,0 +1,7 @@
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mlr --from data/small --opprint put '
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num suma = 0;
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for (a = 1; a <= NR; a += 1) {
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suma += a;
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}
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$suma = suma;
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'
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@ -211,8 +211,7 @@ Miller commands were run with pretty-print-tabular output format.
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• <a href="#While_and_do-while_loops">While and do-while loops</a><br/>
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• <a href="#For-loops">For-loops</a><br/>
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• <a href="#Key-only_for-loops">Key-only for-loops</a><br/>
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• <a href="#For-loop_over_the_current_stream_record">For-loop over the current stream record</a><br/>
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• <a href="#For-loop_over_out-of-stream_variable">For-loop over out-of-stream variable</a><br/>
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• <a href="#Key-value_for-loops">Key-value for-loops</a><br/>
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• <a href="#C-style_triple-for_loops">C-style triple-for loops</a><br/>
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• <a href="#Begin/end_blocks">Begin/end blocks</a><br/>
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• <a href="#Output_statements">Output statements</a><br/>
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@ -2121,7 +2120,18 @@ $ mlr -n put '
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</div>
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<p/>
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<a id="For-loop_over_the_current_stream_record"/><h3>For-loop over the current stream record</h3>
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<p/>Note that the value corresponding to a given key may be gotten as through a
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<b>computed field name</b> using square brackets as in <tt>$[key]</tt> for
|
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stream records, or by indexing the looped-over variable using square brackets.
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<a id="Key-value_for-loops"/><h3>Key-value for-loops </h3>
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<p/>Single-level keys may be gotten at using either <tt>for(k,v)</tt> or
|
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<tt>for((k),v)</tt>; multi-level keys may be gotten at using
|
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<tt>for((k1,k2,k3),v)</tt> and so on. The <tt>v</tt> variable will be bound to
|
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to a scalar value (a string or a number) if the map stops at that level, or to
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a map-valued variable if the map goes deeper. If the map isn’t deep
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enough then the loop body won’t be executed.
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<p/>
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<div class="pokipanel">
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@ -2202,20 +2212,20 @@ wye pan 5 0.5732889198020006 0.8636244699032729 6.436913 25.747654
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<p/>
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It can be confusing to modify the stream record while iterating over a copy of it, so
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instead you might find it simpler to use an out-of-stream variable in the loop and only update
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instead you might find it simpler to use a local variable in the loop and only update
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the stream record after the loop:
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<p/>
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<div class="pokipanel">
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<pre>
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$ mlr --from data/small --opprint put '
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@sum = 0;
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sum = 0;
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for (k,v in $*) {
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if (is_numeric(v)) {
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@sum += $[k];
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sum += $[k];
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}
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}
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$sum = @sum
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$sum = sum
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'
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a b i x y sum
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pan pan 1 0.3467901443380824 0.7268028627434533 2.073593
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@ -2227,18 +2237,15 @@ wye pan 5 0.5732889198020006 0.8636244699032729 6.436913
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</div>
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<p/>
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<a id="For-loop_over_out-of-stream_variable"/><h3>For-loop over out-of-stream variable</h3>
|
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|
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<p/> This is similar to looping over the current stream record except for
|
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additional degrees of freedom: you can start iterating on sub-hashmaps of an
|
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out-of-stream variable; you can loop over nested keys; you can loop over all
|
||||
out-of-stream variables. As with for-loops over stream records, the bound
|
||||
variables are bound to a copy of the sub-hashmap as it was before the loop
|
||||
started. The sub-hashmap is specified by square-bracketed indices after
|
||||
<tt>in</tt>, and additional deeper indices are bound to loop key-variables. The
|
||||
terminal values are bound to the loop value-variable whenever the keys are not
|
||||
too shallow. The value-variable may refer to a terminal (string, number) or it
|
||||
may be map-valued if the map goes deeper. Example indexing is as follows:
|
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<p/>You can also start iterating on sub-hashmaps of an out-of-stream or local
|
||||
variable; you can loop over nested keys; you can loop over all out-of-stream
|
||||
variables. The bound variables are bound to a copy of the sub-hashmap as it
|
||||
was before the loop started. The sub-hashmap is specified by square-bracketed
|
||||
indices after <tt>in</tt>, and additional deeper indices are bound to loop
|
||||
key-variables. The terminal values are bound to the loop value-variable
|
||||
whenever the keys are not too shallow. The value-variable may refer to a
|
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terminal (string, number) or it may be map-valued if the map goes deeper.
|
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Example indexing is as follows:
|
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|
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<p/>
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<div class="pokipanel">
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|
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@ -2261,27 +2268,25 @@ Suppose the out-of-stream variable <tt>@myvar</tt> is populated as follows:
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<p/>
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<div class="pokipanel">
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<pre>
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$ mlr --opprint --from data/small head -n 2 then put -q '
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$ mlr -n put --jknquoteint -q '
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begin {
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@myvar["nesting-is-too-shallow"] = 1;
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@myvar["nesting-is"]["just-right"] = 2;
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@myvar["nesting-is"]["also-just-right"] = 3;
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@myvar["nesting"]["is"]["deeper"] = 4;
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}
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end {
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dump
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@myvar = {
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1: 2,
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3: { 4 : 5 },
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6: { 7: { 8: 9 } }
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}
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}
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end { dump }
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'
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{
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"myvar": {
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"nesting-is-too-shallow": 1,
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"nesting-is": {
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"just-right": 2,
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"also-just-right": 3
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1: 2,
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3: {
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4: 5
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},
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"nesting": {
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"is": {
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"deeper": 4
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6: {
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7: {
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8: 9
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}
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}
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}
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|
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@ -2290,133 +2295,110 @@ $ mlr --opprint --from data/small head -n 2 then put -q '
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</div>
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<p/>
|
||||
|
||||
<p/> Then the too-shallow parts — indexed by the basename <tt>myvar</tt>
|
||||
and the index <tt>"nesting-is-too-shallow"</tt> — have depth two
|
||||
(basename and one index specify a terminal value) and can be gotten as follows:
|
||||
<p/> Then we can get at various values as follows:
|
||||
|
||||
<table><tr><td>
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small head -n 2 then put -q '
|
||||
$ mlr -n put --jknquoteint -q '
|
||||
begin {
|
||||
@myvar["nesting-is-too-shallow"] = 1;
|
||||
@myvar["nesting-is"]["just-right"] = 2;
|
||||
@myvar["nesting-is"]["also-just-right"] = 3;
|
||||
@myvar["nesting"]["is"]["deeper"] = 4;
|
||||
@myvar = {
|
||||
1: 2,
|
||||
3: { 4 : 5 },
|
||||
6: { 7: { 8: 9 } }
|
||||
}
|
||||
}
|
||||
end {
|
||||
for (k, v in @myvar) {
|
||||
@terminal[k] = v
|
||||
print
|
||||
"key=" . k .
|
||||
",valuetype=" . typeof(v);
|
||||
}
|
||||
emit @terminal, "index1"
|
||||
}
|
||||
'
|
||||
index1=nesting-is-too-shallow,terminal=1
|
||||
index1=nesting-is,just-right=2,also-just-right=3
|
||||
index1=nesting,deeper=4
|
||||
key=1,valuetype=int
|
||||
key=3,valuetype=map
|
||||
key=6,valuetype=map
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
</td><td>
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small head -n 2 then put -q '
|
||||
$ mlr -n put --jknquoteint -q '
|
||||
begin {
|
||||
@myvar["nesting-is-too-shallow"] = 1;
|
||||
@myvar["nesting-is"]["just-right"] = 2;
|
||||
@myvar["nesting-is"]["also-just-right"] = 3;
|
||||
@myvar["nesting"]["is"]["deeper"] = 4;
|
||||
}
|
||||
end {
|
||||
for ((k1, k2), v in @*) {
|
||||
@terminal[k1][k2] = v
|
||||
@myvar = {
|
||||
1: 2,
|
||||
3: { 4 : 5 },
|
||||
6: { 7: { 8: 9 } }
|
||||
}
|
||||
emit @terminal, "basename", "index1"
|
||||
}
|
||||
'
|
||||
basename=myvar,index1=nesting-is-too-shallow,terminal=1
|
||||
basename=myvar,index1=nesting-is,just-right=2,also-just-right=3
|
||||
basename=myvar,index1=nesting,deeper=4
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
|
||||
<p/>The <tt>"just-right"</tt> parts have depth three (basename and two indices
|
||||
specify a terminal value) and can be gotten at by any of the following:
|
||||
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small head -n 2 then put -q '
|
||||
begin {
|
||||
@myvar["nesting-is-too-shallow"] = 1;
|
||||
@myvar["nesting-is"]["just-right"] = 2;
|
||||
@myvar["nesting-is"]["also-just-right"] = 3;
|
||||
@myvar["nesting"]["is"]["deeper"] = 4;
|
||||
}
|
||||
end {
|
||||
for ((k1), v in @myvar["nesting-is"]) {
|
||||
@terminal[k1] = v
|
||||
}
|
||||
emit @terminal, "index1"
|
||||
}
|
||||
'
|
||||
index1=just-right,terminal=2
|
||||
index1=also-just-right,terminal=3
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small head -n 2 then put -q '
|
||||
begin {
|
||||
@myvar["nesting-is-too-shallow"] = 1;
|
||||
@myvar["nesting-is"]["just-right"] = 2;
|
||||
@myvar["nesting-is"]["also-just-right"] = 3;
|
||||
@myvar["nesting"]["is"]["deeper"] = 4;
|
||||
}
|
||||
end {
|
||||
for ((k1, k2), v in @myvar) {
|
||||
@terminal[k1][k2] = v
|
||||
print
|
||||
"key1=" . k1 .
|
||||
",key2=" . k2 .
|
||||
",valuetype=" . typeof(v);
|
||||
}
|
||||
emit @terminal, "index1", "index2"
|
||||
}
|
||||
'
|
||||
index1=nesting-is,index2=just-right,terminal=2
|
||||
index1=nesting-is,index2=also-just-right,terminal=3
|
||||
index1=nesting,index2=is,deeper=4
|
||||
key1=3,key2=4,valuetype=int
|
||||
key1=6,key2=7,valuetype=map
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
</td><td>
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small head -n 2 then put -q '
|
||||
$ mlr -n put --jknquoteint -q '
|
||||
begin {
|
||||
@myvar["nesting-is-too-shallow"] = 1;
|
||||
@myvar["nesting-is"]["just-right"] = 2;
|
||||
@myvar["nesting-is"]["also-just-right"] = 3;
|
||||
@myvar["nesting"]["is"]["deeper"] = 4;
|
||||
@myvar = {
|
||||
1: 2,
|
||||
3: { 4 : 5 },
|
||||
6: { 7: { 8: 9 } }
|
||||
}
|
||||
}
|
||||
end {
|
||||
for ((k1, k2, k3), v in @*) {
|
||||
@terminal[k1][k2][k3] = v
|
||||
for ((k1, k2), v in @myvar[6]) {
|
||||
print
|
||||
"key1=" . k1 .
|
||||
",key2=" . k2 .
|
||||
",valuetype=" . typeof(v);
|
||||
}
|
||||
emit @terminal, "basename", "index1", "index2"
|
||||
}
|
||||
'
|
||||
basename=myvar,index1=nesting-is,index2=just-right,terminal=2
|
||||
basename=myvar,index1=nesting-is,index2=also-just-right,terminal=3
|
||||
basename=myvar,index1=nesting,index2=is,deeper=4
|
||||
key1=7,key2=8,valuetype=int
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
</td></tr></table>
|
||||
|
||||
<a id="C-style_triple-for_loops"/><h3>C-style triple-for loops</h3>
|
||||
|
||||
<p/> These are supported as follows:
|
||||
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
$ mlr --from data/small --opprint put '
|
||||
num suma = 0;
|
||||
for (a = 1; a <= NR; a += 1) {
|
||||
suma += a;
|
||||
}
|
||||
$suma = suma;
|
||||
'
|
||||
a b i x y suma
|
||||
pan pan 1 0.3467901443380824 0.7268028627434533 1
|
||||
eks pan 2 0.7586799647899636 0.5221511083334797 3
|
||||
wye wye 3 0.20460330576630303 0.33831852551664776 6
|
||||
eks wye 4 0.38139939387114097 0.13418874328430463 10
|
||||
wye pan 5 0.5732889198020006 0.8636244699032729 15
|
||||
</pre>
|
||||
</div>
|
||||
<p/>
|
||||
<p/>
|
||||
<div class="pokipanel">
|
||||
<pre>
|
||||
|
|
@ -2445,13 +2427,22 @@ Notes:
|
|||
|
||||
<li/> In <tt>for (start; continuation; update) { body }</tt>, the start,
|
||||
continuation, and update statements may be empty, single statements, or
|
||||
multiple comma-separated statements. If the continuation is empty it defaults
|
||||
multiple comma-separated statements. If the continuation is empty (e.g. <tt>for(i=1;;i+=1)</tt>) it defaults
|
||||
to true.
|
||||
|
||||
<li/> In particular, you may use <tt>$</tt>-variables and/or
|
||||
<tt>@</tt>-variables in the start, continuation, and/or update steps (as well
|
||||
as the body, of course).
|
||||
|
||||
<li/> The typedecls such as <tt>int</tt> or <tt>num</tt> are optional. If a
|
||||
typedecl is provided (for a local variable), it binds a variable scoped to the
|
||||
for-loop regardless of whether a same-name variable is present in outer scope.
|
||||
If a typedecl is not provided, then the variable is scoped to the for-loop if
|
||||
no same-name variable is present in outer scope, or if a same-name variable is
|
||||
present in outer scope then it is modified.
|
||||
|
||||
<li/> Miller has no <tt>++</tt> or <tt>--</tt> operators.
|
||||
|
||||
<li/> As with all for/if/while statements in Miller, the curly braces are
|
||||
required even if the body is a single statement, or empty.
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue