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tools", lightened and sepia-toned. Over this was placed a Mac Terminal app with
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Miller commands were run with pretty-print-tabular output format.
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<br/>• <a href="index.html">About Miller</a>
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<br/>• <a href="file-formats.html">File formats</a>
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<br/>• <a href="feature-comparison.html">Miller features in the context of the Unix toolkit</a>
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<br/>• <a href="record-heterogeneity.html">Record-heterogeneity</a>
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<br/>• <a href="https://github.com/johnkerl/miller">GitHub repo</a>
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<br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/>
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<br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/>
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<br/> <br/> <br/> <br/> <br/> <br/>
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<td>
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<center> <titleinbody> FAQ </titleinbody> </center>
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<div class="pokitoc">
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<center><b>Contents:</b></center>
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• <a href="#No_output_at_all">No output at all</a><br/>
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• <a href="#Fields_not_selected">Fields not selected</a><br/>
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• <a href="#Diagnosing_delimiter_specifications">Diagnosing delimiter specifications</a><br/>
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• <a href="#Error-output_in_certain_string_cases">Error-output in certain string cases</a><br/>
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• <a href="#How_do_I_parse_log-file_output?">How do I parse log-file output?</a><br/>
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• <a href="#How_do_I_examine_then-chaining?">How do I examine then-chaining?</a><br/>
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• <a href="#How_do_I_do_arithmetic_on_fields_with_currency_symbols?">How do I do arithmetic on fields with currency symbols?</a><br/>
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</div>
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<p/>
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<a id="No_output_at_all"/><h1>No output at all</h1>
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<p/>Check the line-terminators of the data, e.g. with the command-line
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<tt>file</tt> program. Example: for CSV, Miller’s default line terminator
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is CR/LF (carriage return followed by linefeed, following
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<a href="https://tools.ietf.org/html/rfc4180">RFC4180</a>). Yet if your CSV has
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*nix-standard LF line endings, Miller will keep reading the file looking for a
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CR/LF which never appears. Solution in this case: tell Miller the input has LF line-terminator, e.g. <b>mlr --csv --rs
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lf {remaining arguments ...}</b>.
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<p/>Also try <tt>od -xcv</tt> and/or <tt>cat -e</tt> on your file to check for non-printable characters.
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<a id="Fields_not_selected"/><h1>Fields not selected</h1>
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<p/>Check the field-separators of the data, e.g. with the command-line
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<tt>head</tt> program. Example: for CSV, Miller’s default record
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separator is comma; if your data is tab-delimited, e.g. <tt>aTABbTABc</tt>,
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then Miller won’t find three fields named <tt>a</tt>, <tt>b</tt>, and
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<tt>c</tt> but rather just one named <tt>aTABbTABc</tt>. Solution in this
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case: <tt>mlr --fs tab {remaining arguments ...}</tt>.
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<p/>Also try <tt>od -xcv</tt> and/or <tt>cat -e</tt> on your file to check for non-printable characters.
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<a id="Diagnosing_delimiter_specifications"/><h1>Diagnosing delimiter specifications</h1>
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<p/>
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<div class="pokipanel">
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<pre>
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# Use the `file` command to see if there are CR/LF terminators (in this case,
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# there are not):
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$ file colours.csv
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colours.csv: UTF-8 Unicode text
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# Look at the file to find names of fields
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$ cat colours.csv
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KEY;DE;EN;ES;FI;FR;IT;NL;PL;RO;TR
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masterdata_colourcode_1;Weiß;White;Blanco;Valkoinen;Blanc;Bianco;Wit;Biały;Alb;Beyaz
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masterdata_colourcode_2;Schwarz;Black;Negro;Musta;Noir;Nero;Zwart;Czarny;Negru;Siyah
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# Try (unsuccessfully) to extract a few fields:
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$ mlr --csv cut -f KEY,PL,RO colours.csv
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(no output)
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# Use LF record separator (--rs lf) since the file doesn't have CR/LF line
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# endings -- but still unsuccessfully:
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$ mlr --csv --rs lf cut -f KEY,PL,RO colours.csv
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(only blank lines appear)
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# Use XTAB output format to get a sharper picture of where records/fields
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# are being split:
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$ mlr --icsv --irs lf --oxtab cat colours.csv
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KEY;DE;EN;ES;FI;FR;IT;NL;PL;RO;TR masterdata_colourcode_1;Weiß;White;Blanco;Valkoinen;Blanc;Bianco;Wit;Biały;Alb;Beyaz
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KEY;DE;EN;ES;FI;FR;IT;NL;PL;RO;TR masterdata_colourcode_2;Schwarz;Black;Negro;Musta;Noir;Nero;Zwart;Czarny;Negru;Siyah
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# Using XTAB output format makes it clearer that KEY;DE;...;RO;TR is being
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# treated as a single field name in the CSV header, and likewise each
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# subsequent line is being treated as a single field value. This is because
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# the default field separator is a comma but we have semicolons here.
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# Use XTAB again with different field separator (--fs semicolon):
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$ mlr --icsv --irs lf --ifs semicolon --oxtab cat colours.csv
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KEY masterdata_colourcode_1
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DE Weiß
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EN White
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ES Blanco
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FI Valkoinen
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FR Blanc
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IT Bianco
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NL Wit
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PL Biały
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RO Alb
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TR Beyaz
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KEY masterdata_colourcode_2
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DE Schwarz
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EN Black
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ES Negro
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FI Musta
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FR Noir
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IT Nero
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NL Zwart
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PL Czarny
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RO Negru
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TR Siyah
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# Using the new field-separator, retry the cut:
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$ mlr --csv --rs lf --fs semicolon cut -f KEY,PL,RO colours.csv
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KEY;PL;RO
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masterdata_colourcode_1;Biały;Alb
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masterdata_colourcode_2;Czarny;Negru
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</pre>
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</div>
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<p/>
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<a id="Error-output_in_certain_string_cases"/><h1>Error-output in certain string cases</h1>
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<p/> <tt>mlr put '$y = string($x); $z=$y.$y'</tt> gives <tt>(error)</tt> on
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numeric data such as <tt>x=123</tt> while <tt>mlr put
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'$z=string($x).string($x)'</tt> does not. This is because in the former case
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<tt>y</tt> is computed and stored as a string, then re-parsed as an integer,
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for which string-concatenation is an invalid operator.
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<a id="How_do_I_parse_log-file_output?"/><h1>How do I parse log-file output?</h1>
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<p/>Suppose you have log-file lines such as
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<p/>
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<div class="pokipanel">
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<pre>
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2015-10-08 08:29:09,445 INFO com.company.path.to.ClassName @ [sometext] various/sorts/of data {& punctuation} hits=1 status=0 time=2.378
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</pre>
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</div>
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<p/>
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I prefer to pre-filter with <tt>grep</tt> and/or <tt>sed</tt> to extract the structured text, then hand that to Miller. Example:
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<p/>
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<div class="pokipanel">
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<pre>
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grep 'various sorts' *.log | sed 's/.*} //' | mlr --fs space --repifs --oxtab stats1 -a min,p10,p50,p90,max -f time -g status
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</pre>
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</div>
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<p/>
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<a id="How_do_I_examine_then-chaining?"/><h1>How do I examine then-chaining?</h1>
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<p/>Then-chaining found in Miller is intended to function the same as Unix
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pipes. You can print your data one pipeline step at a time, to see what
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intermediate
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output at one step becomes the input to the next step.
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<p/>First, review the input data:
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<p/>
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<div class="pokipanel">
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<pre>
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$ cat data/then-example.csv
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Status,Payment_Type,Amount
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paid,cash,10.00
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pending,debit,20.00
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paid,cash,50.00
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pending,credit,40.00
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paid,debit,30.00
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</pre>
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</div>
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<p/>
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Next, run the first step of your command, omitting anything from the first <tt>then</tt> onward:
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<p/>
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<div class="pokipanel">
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<pre>
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$ mlr --icsv --rs lf --opprint count-distinct -f Status,Payment_Type data/then-example.csv
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Status Payment_Type count
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paid cash 2
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pending debit 1
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pending credit 1
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paid debit 1
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</pre>
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</div>
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<p/>
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After that, run it with the next <tt>then</tt> step included:
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<p/>
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<div class="pokipanel">
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<pre>
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$ mlr --icsv --rs lf --opprint count-distinct -f Status,Payment_Type then sort -nr count data/then-example.csv
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Status Payment_Type count
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paid cash 2
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pending debit 1
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pending credit 1
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paid debit 1
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</pre>
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</div>
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<p/>
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Now if you include another <tt>then</tt> step after this, the columns <tt>Status</tt>,
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<tt>Payment_Type</tt>, and <tt>count</tt> will be its input.
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<p/>Note, by the way, that you’ll get the same results using pipes:
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<p/>
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<div class="pokipanel">
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<pre>
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$ mlr --csv --rs lf count-distinct -f Status,Payment_Type data/then-example.csv | mlr --icsv --rs lf --opprint sort -nr count
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Status Payment_Type count
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paid cash 2
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pending debit 1
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pending credit 1
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paid debit 1
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</pre>
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</div>
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<p/>
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<a id="How_do_I_do_arithmetic_on_fields_with_currency_symbols?"/><h1>How do I do arithmetic on fields with currency symbols?</h1>
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<p/>
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<div class="pokipanel">
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<pre>
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$ cat sample.csv
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EventOccurred,EventType,Description,Status,PaymentType,NameonAccount,TransactionNumber,Amount
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10/1/2015,Charged Back,Reason: Authorization Revoked By Customer,Disputed,Checking,John,1,$230.36
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10/1/2015,Charged Back,Reason: Authorization Revoked By Customer,Disputed,Checking,Fred,2,$32.25
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10/1/2015,Charged Back,Reason: Customer Advises Not Authorized,Disputed,Checking,Bob,3,$39.02
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10/1/2015,Charged Back,Reason: Authorization Revoked By Customer,Disputed,Checking,Alice,4,$57.54
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10/1/2015,Charged Back,Reason: Authorization Revoked By Customer,Disputed,Checking,Jungle,5,$230.36
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10/1/2015,Charged Back,Reason: Payment Stopped,Disputed,Checking,Joe,6,$281.96
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10/2/2015,Charged Back,Reason: Customer Advises Not Authorized,Disputed,Checking,Joseph,7,$188.19
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10/2/2015,Charged Back,Reason: Customer Advises Not Authorized,Disputed,Checking,Joseph,8,$188.19
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10/2/2015,Charged Back,Reason: Payment Stopped,Disputed,Checking,Anthony,9,$250.00
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$ mlr --icsv --opprint cat sample.csv
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EventOccurred EventType Description Status PaymentType NameonAccount TransactionNumber Amount
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10/1/2015 Charged Back Reason: Authorization Revoked By Customer Disputed Checking John 1 $230.36
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10/1/2015 Charged Back Reason: Authorization Revoked By Customer Disputed Checking Fred 2 $32.25
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10/1/2015 Charged Back Reason: Customer Advises Not Authorized Disputed Checking Bob 3 $39.02
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10/1/2015 Charged Back Reason: Authorization Revoked By Customer Disputed Checking Alice 4 $57.54
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10/1/2015 Charged Back Reason: Authorization Revoked By Customer Disputed Checking Jungle 5 $230.36
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10/1/2015 Charged Back Reason: Payment Stopped Disputed Checking Joe 6 $281.96
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10/2/2015 Charged Back Reason: Customer Advises Not Authorized Disputed Checking Joseph 7 $188.19
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10/2/2015 Charged Back Reason: Customer Advises Not Authorized Disputed Checking Joseph 8 $188.19
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10/2/2015 Charged Back Reason: Payment Stopped Disputed Checking Anthony 9 $250.00
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$ mlr --csv put '$Amount = sub(string($Amount), "\$", "")' then stats1 -a sum -f Amount sample.csv
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Amount_sum
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1497.870000
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$ mlr --csv --ofmt '%.2lf' put '$Amount = sub(string($Amount), "\$", "")' then stats1 -a sum -f Amount sample.csv
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Amount_sum
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1497.87
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</pre>
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</div>
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<p/>
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