# 📊 Column filters
| `&N:S` | Split value using separator `S`, output `N`-th column.<br>Column indices `N` start from 1.<br>Use `-N` for backward indexing.<br>Any other character than `:` can be also used as a delimiter.<br>Use of `/` as a delimiter has special meaning (see below). |
| `&N/S` | Split value using regular expression `S`, output `N`-th column. |
| `&N` | Split value using global separator, output `N`-th column. |
By default, the global separator is *horizontal tab*.
- Use `-s, --separator` option to change it to a string.
- Use `-S, --separator-regex` option to change it to a regular expression.
```bash
```
Examples:
| `a1\tb2` | `{&1}` | `a1` | | `a1\tb2` | `{&-1}` | `b2` |
| `a1\tb2` | `{&2}` | `b2` | | `a1\tb2` | `{&-2}` | `a1` |
| `a1--b2` | `{&1:-}` | `a1` | | `a1--b2` | `{&-1:-}` | `b2` |
| `a1--b2` | `{&2:-}` | *(empty)* | | `a1--b2` | `{&-2:-}` | *(empty)* |
| `a1--b2` | `{&3:-}` | `b2` | | `a1--b2` | `{&-3:-}` | `a1` |
| `a1--b2` | `{&1/[^a-z]+}` | `a` | | `a1--b2` | `{&-1/[^a-z]+}` | *(empty)* |
| `a1--b2` | `{&2/[^a-z]+}` | `b` | | `a1--b2` | `{&-2/[^a-z]+}` | `b` |
| `a1--b2` | `{&3/[^a-z]+}` | *(empty)* | | `a1--b2` | `{&-3/[^a-z]+}` | `a` |