mlr sparsify (#1498)

* mlr sparsify

* regression-test cases

* typofix

* Remove mods due to processor-architecture change

test/cases/cli-help/0001/expout

@@ -988,6 +988,18 @@ Options:
 -r        Recursively sort subobjects/submaps, e.g. for JSON input.
 -h|--help Show this message.
 
+================================================================
+sparsify
+Usage: mlr sparsify [options]
+Unsets fields for which the key is the empty string (or, optionally, another
+specified value). Only makes sense with output format not being CSV or TSV.
+Options:
+-s {filler string} What values to remove. Defaults to the empty string.
+-f {a,b,c} Specify field names to be operated on; any other fields won't be
+           modified. The default is to modify all fields.
+-h|--help  Show this message.
+Example: if input is a=1,b=,c=3 then output is a=1,c=3.
+
 ================================================================
 split
 Usage: mlr split [options] {filename}

test/cases/verb-sparsify/0001/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify

test/cases/verb-sparsify/0001/expout

@@ -0,0 +1,17 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5
+},
+{},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0002/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f a

test/cases/verb-sparsify/0002/expout

@@ -0,0 +1,21 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "b": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0003/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f b

test/cases/verb-sparsify/0003/expout

@@ -0,0 +1,21 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "a": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0004/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f b,c

test/cases/verb-sparsify/0004/expout

@@ -0,0 +1,19 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5
+},
+{
+  "a": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0005/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -s 1

test/cases/verb-sparsify/0005/expout

@@ -0,0 +1,21 @@
+[
+{
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "a": "",
+  "b": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0006/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f a -s 1

test/cases/verb-sparsify/0006/expout

@@ -0,0 +1,21 @@
+[
+{
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "a": "",
+  "b": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0007/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f b -s 1

test/cases/verb-sparsify/0007/expout

@@ -0,0 +1,22 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "a": "",
+  "b": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/cases/verb-sparsify/0008/cmd

@@ -0,0 +1 @@
+mlr --c2j --from test/input/sparsify-input.csv sparsify -f b,c -s 1

test/cases/verb-sparsify/0008/expout

@@ -0,0 +1,22 @@
+[
+{
+  "a": 1,
+  "b": 2,
+  "c": 3
+},
+{
+  "a": 4,
+  "b": 5,
+  "c": ""
+},
+{
+  "a": "",
+  "b": "",
+  "c": ""
+},
+{
+  "a": 7,
+  "b": 8,
+  "c": 9
+}
+]

test/input/sparsify-input.csv

@@ -0,0 +1,5 @@
+a,b,c
+1,2,3
+4,5,
+,,
+7,8,9