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FAQ entry for #285: carriage returns in field names #953

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Feb 21, 2022
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FAQ entry for #285: carriage returns in field names #953

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33 changes: 33 additions & 0 deletions docs/src/operating-on-all-fields.md
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,39 @@ a_b_c def g_h_i
9987 3312 4543
</pre>

## Bulk rename of fields with carriage returns

The previous example isn't sufficient when there are carriage returns in the field names. Here we can use
the [Miller programming language](miller-programming-language.md):

<pre class="pre-highlight-in-pair">
<b>cat data/header-lf.csv</b>
</pre>
<pre class="pre-non-highlight-in-pair">
"field
A",field B
1,2
3,3
6,6
</pre>

<pre class="pre-highlight-in-pair">
<b>mlr --csv --from data/header-lf.csv put '</b>
<b> map inrec = $*;</b>
<b> $* = {};</b>
<b> for (oldkey, value in inrec) {</b>
<b> newkey = clean_whitespace(gsub(oldkey, "\n", " "));</b>
<b> $[newkey] = value;</b>
<b> }</b>
<b>'</b>
</pre>
<pre class="pre-non-highlight-in-pair">
field A,field B
1,2
3,3
6,6
</pre>

## Search-and-replace over all fields

How to do `$name = gsub($name, "old", "new")` for all fields?
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20 changes: 20 additions & 0 deletions docs/src/operating-on-all-fields.md.in
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Expand Up @@ -28,6 +28,26 @@ GENMD-RUN-COMMAND
mlr --icsv --opprint put -f data/bulk-rename-for-loop.mlr data/spaces.csv
GENMD-EOF

## Bulk rename of fields with carriage returns

The previous example isn't sufficient when there are carriage returns in the field names. Here we can use
the [Miller programming language](miller-programming-language.md):

GENMD-RUN-COMMAND
cat data/header-lf.csv
GENMD-EOF

GENMD-RUN-COMMAND
mlr --csv --from data/header-lf.csv put '
map inrec = $*;
$* = {};
for (oldkey, value in inrec) {
newkey = clean_whitespace(gsub(oldkey, "\n", " "));
$[newkey] = value;
}
'
GENMD-EOF

## Search-and-replace over all fields

How to do `$name = gsub($name, "old", "new")` for all fields?
Expand Down