`drop` is used for removing the last row. Passing a number allows dropping N rows.
Here we introduce the same logic for dropping columns instead.
You can certainly remove columns by using `reject`, however, there could be cases
where we are interested in removing columns from tables that contain, say, a big
number of columns. Using `reject` becomes impractical, especially when you don't
care about the column names that could either be known or not known when exploring
tables.
```
> echo [[lib, extension]; [nu-core, rs] [rake, rb]]
─────────┬───────────
lib │ extension
─────────┼───────────
nu-core │ rs
rake │ rb
─────────┴───────────
```
```
> echo [[lib, extension]; [nu-core, rs] [rake, rb]] | drop column
─────────
lib
─────────
nu-core
rake
─────────
```
There are many use cases. Here we introduce the following:
- The rows can be rolled `... | roll` (up) or `... | roll down`
- Columns can be rolled too (the default is on the `left`, you can pass `... | roll column --opposite` to roll in the other direction)
- You can `roll` the cells of a table and keeping the header names in the same order (`... | roll column --cells-only`)
- Above examples can also be passed (Ex. `... | roll down 3`) a number to tell how many places to roll.
Basic working example with rolling columns:
```
> echo '00000100'
| split chars
| each { str to-int }
| rotate counter-clockwise _
| reject _
| rename bit1 bit2 bit3 bit4 bit5 bit6 bit7 bit8
───┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────
# │ bit1 │ bit2 │ bit3 │ bit4 │ bit5 │ bit6 │ bit7 │ bit8
───┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 1 │ 0 │ 0
───┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────
```
We want to "shift" three bits to the left of the bitstring (four in decimal), let's try it:
```
> echo '00000100'
| split chars
| each { str to-int }
| rotate counter-clockwise _
| reject _
| rename bit1 bit2 bit3 bit4 bit5 bit6 bit7 bit8
| roll column 3
───┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────
# │ bit4 │ bit5 │ bit6 │ bit7 │ bit8 │ bit1 │ bit2 │ bit3
───┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
0 │ 0 │ 0 │ 1 │ 0 │ 0 │ 0 │ 0 │ 0
───┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────
```
The tables was rolled correctly (32 in decimal, for above bitstring). However, the *last three header names* look confusing.
We can roll the cell contents only to fix it.
```
> echo '00000100'
| split chars
| each { str to-int }
| rotate counter-clockwise _
| reject _
| rename bit1 bit2 bit3 bit4 bit5 bit6 bit7 bit8
| roll column 3 --cells-only
───┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────
# │ bit1 │ bit2 │ bit3 │ bit4 │ bit5 │ bit6 │ bit7 │ bit8
───┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
0 │ 0 │ 0 │ 1 │ 0 │ 0 │ 0 │ 0 │ 0
───┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────
```
There we go. Let's compute it's decimal value now (should be 32)
```
> echo '00000100'
| split chars
| each { str to-int }
| rotate counter-clockwise _
| reject _
| roll column 3 --cells-only
| pivot bit --ignore-titles
| get bit
| reverse
| each --numbered { = $it.item * (2 ** $it.index) }
| math sum
32
```
* standardize on how to get file size
* forgot to remove comment
* make specified size lowercase
* fix the test due to precision
* added another test
* Update README.md
add contributors graphic
* clippy - test adjustment
* tweaked matching
* move commands, futures.rs, script.rs, utils
* move over maybe_print_errors
* add nu_command crate references to nu_cli
* in commands.rs open up to pub mod from pub(crate)
* nu-cli, nu-command, and nu tests are now passing
* cargo fmt
* clean up nu-cli/src/prelude.rs
* code cleanup
* for some reason lex.rs was not formatted, may be causing my error
* remove mod completion from lib.rs which was not being used along with quickcheck macros
* add in allow unused imports
* comment out one failing external test; comment out one failing internal test
* revert commenting out failing tests; something else might be going on; someone with a windows machine should check and see what is going on with these failing windows tests
* Update Cargo.toml
Extend the optional features to nu-command
Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>
