# Description
This pr is addressing feedback from
https://github.com/nushell/nushell/pull/12277#issuecomment-2027246752
Currently I think it's fine to replace `--legacy` flag with `--guess`
one. Only use `guess_width` algorithm if `--guess` is provided.
# User-Facing Changes
So it won't be a breaking change to previous version.
# Description
@fdncred found another histogram based algorithm to detect columns, and
rewrite it in rust: https://github.com/fdncred/guess-width
I have tested it manually, and it works good with `df`, `docker ps`,
`^ps`. This pr is going to use the algorithm in `detect columns`
Fix: #4183
The pitfall of new algorithm:
1. it may not works well if there isn't too much rows of input
2. it may not works well if the length of value is less than the header
to value, e.g:
```
c1 c2 c3 c4 c5
a b c d e
g h i j k
g a a q d
a v c q q | detect columns
```
In this case, users might need to use ~~`--old`~~ `--legacy` to make it
works well.
# User-Facing Changes
User might need to add ~~`--old`~~ `--legacy` to scripts if they find
`detect columns` in their scripts broken.
# Tests + Formatting
Done
# After Submitting
NaN
fix `detect columns` with flag `-c, --combine-columns` run failed when
using some range
- fixes#9653fix#9653 the cmd detect columns with the flag -c, --combine-columns run
failed when using some range.
add unit test for the command `detect columns`
```text
Attempt to automatically split text into multiple columns.
Usage:
> detect columns {flags}
Flags:
-h, --help - Display the help message for this command
-s, --skip <Int> - number of rows to skip before detecting
-n, --no-headers - don't detect headers
-c, --combine-columns <Range> - columns to be combined; listed as a range
Signatures:
<string> | detect columns -> <table>
Examples:
Splits string across multiple columns
> 'a b c' | detect columns -n
╭───┬─────────┬─────────┬─────────╮
│ # │ column0 │ column1 │ column2 │
├───┼─────────┼─────────┼─────────┤
│ 0 │ a │ b │ c │
╰───┴─────────┴─────────┴─────────╯
Splits a multi-line string into columns with headers detected
> $'c1 c2 c3 c4 c5(char nl)a b c d e' | detect columns
╭───┬────┬────┬────┬────┬────╮
│ # │ c1 │ c2 │ c3 │ c4 │ c5 │
├───┼────┼────┼────┼────┼────┤
│ 0 │ a │ b │ c │ d │ e │
╰───┴────┴────┴────┴────┴────╯
> $'c1 c2 c3 c4 c5(char nl)a b c d e' | detect columns -c 0..1
╭───┬─────┬────┬────┬────╮
│ # │ c1 │ c3 │ c4 │ c5 │
├───┼─────┼────┼────┼────┤
│ 0 │ a b │ c │ d │ e │
╰───┴─────┴────┴────┴────╯
Splits a multi-line string into columns with headers detected
> $'c1 c2 c3 c4 c5(char nl)a b c d e' | detect columns -c -2..-1
╭───┬────┬────┬────┬─────╮
│ # │ c1 │ c2 │ c3 │ c4 │
├───┼────┼────┼────┼─────┤
│ 0 │ a │ b │ c │ d e │
╰───┴────┴────┴────┴─────╯
Splits a multi-line string into columns with headers detected
> $'c1 c2 c3 c4 c5(char nl)a b c d e' | detect columns -c 2..
╭───┬────┬────┬───────╮
│ # │ c1 │ c2 │ c3 │
├───┼────┼────┼───────┤
│ 0 │ a │ b │ c d e │
╰───┴────┴────┴───────╯
Parse external ls command and combine columns for datetime
> ^ls -lh | detect columns --no-headers --skip 1 --combine-columns 5..7
```
