nushell/docs/commands/from-csv.md
David Mason b3c021899c combine functions behind to/from-c/tsv commands
fixes #969, admittedly without a --delimiter alias

moves from_structured_data.rs to from_delimited_data.rs to better
identify its scope and adds to_delimited_data.rs. Now csv and tsv both
use the same code, tsv passes in a fixed '\t' argument where csv passes
in the value of --separator
2019-11-19 16:02:35 +00:00

117 lines
3.8 KiB
Markdown

# from-csv
Converts csv data into table. Use this when nushell cannot dertermine the input file extension.
## Example
Let's say we have the following file :
```shell
> cat pets.txt
animal, name, age
cat, Tom, 7
dog, Alfred, 10
chameleon, Linda, 1
```
`pets.txt` is actually a .csv file but it has the .txt extension, `open` is not able to convert it into a table :
```shell
> open pets.txt
animal, name, age
cat, Tom, 7
dog, Alfred, 10
chameleon, Linda, 1
```
To get a table from `pets.txt` we need to use the `from-csv` command :
```shell
> open pets.txt | from-csv
━━━┯━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━
# │ animal │ name │ age
───┼───────────┼─────────┼──────
0 │ cat │ Tom │ 7
1 │ dog │ Alfred │ 10
2 │ chameleon │ Linda │ 1
━━━┷━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━
```
To ignore the csv headers use `--headerless` :
```shell
━━━┯━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━━━━
# │ Column1 │ Column2 │ Column3
───┼───────────┼─────────┼─────────
0 │ dog │ Alfred │ 10
1 │ chameleon │ Linda │ 1
━━━┷━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━━━━
```
To split on a character other than ',' use `--separator` :
```shell
> open pets.txt
animal; name; age
cat; Tom; 7
dog; Alfred; 10
chameleon; Linda; 1
```
```shell
> open pets.txt | from-csv --separator ';'
━━━┯━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━
# │ animal │ name │ age
───┼───────────┼─────────┼──────
0 │ cat │ Tom │ 7
1 │ dog │ Alfred │ 10
2 │ chameleon │ Linda │ 1
━━━┷━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━
```
To use this command to open a csv with separators other than a comma, use the `--raw` switch of `open` to open the csv, othewise the csv will enter `from-csv` as a table split on commas rather than raw text.
```shell
> mv pets.txt pets.csv
> open pets.csv | from-csv --separator ';'
error: Expected a string from pipeline
- shell:1:16
1 | open pets.csv | from-csv --separator ';'
| ^^^^^^^^ requires string input
- shell:1:0
1 | open pets.csv | from-csv --separator ';'
| value originates from here
> open pets.csv --raw | from-csv --separator ';'
━━━┯━━━━━━━━━━━┯━━━━━━━━━┯━━━━━━
# │ animal │ name │ age
───┼───────────┼─────────┼──────
0 │ cat │ Tom │ 7
1 │ dog │ Alfred │ 10
2 │ chameleon │ Linda │ 1
━━━┷━━━━━━━━━━━┷━━━━━━━━━┷━━━━━━
```
The string '\t' can be used to separate on tabs. Note that this is the same as using the from-tsv command.
Newlines '\n' are not acceptable separators.
Note that separators are currently provided as strings and need to be wrapped in quotes.
```shell
> open pets.csv --raw | from-csv --separator ;
- shell:1:43
1 | open pets.csv --raw | from-csv --separator ;
| ^
```
It is also considered an error to use a separator greater than one char :
```shell
> open pets.txt | from-csv --separator '123'
error: Expected a single separator char from --separator
- shell:1:37
1 | open pets.txt | from-csv --separator '123'
| ^^^^^ requires a single character string input
```