tass 0.9.0

A pager for tabular data
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<h1 align="center">Tass</h1>
<p align="center">A pager for tabular data</p>

It's like `less`, but for CSV and parquet files!  It looks like this:

<img src="https://github.com/asayers/tass/raw/master/demo.png">

You can see tass's schema inference in action here. The fourth and fifth
columns only contains a small number of unique values, so tass colour-codes
them automatically. The columns to the right of those are numerical, so tass
right-aligns them and shows negative values in red.

<img src="https://github.com/asayers/tass/raw/master/demo.gif">

This demo shows data being piped into (an older version of) tass. You can also
open files which are still being appeanded to, and new rows will appear as the
file grows.

## Installing

If you already have rust, you can install tass like this:

```
$ cargo install tass
```

## Usage

You can pass a filename, or pipe data to stdin:

```
$ tass mydata.csv
$ cat mydata.csv | tass
```

Key                                               | Action
--------------------------------------------------|--------------------------------------------------
<kbd>Up</kbd>/<kbd>j</kbd>,  <kbd>PageUp</kbd>    | Move up one row, page
<kbd>Down</kbd>/<kbd>k</kbd>,<kbd>PageDown</kbd>  | Move down one row, page
<kbd>Left</kbd>/<kbd>h</kbd>                      | Move left one column
<kbd>Right</kbd>/<kbd>l</kbd>                     | Move right one column
<kbd>Home</kbd>, <kbd>End</kbd>                   | Move to start/end of file
number <kbd>g</kbd>                               | Move to line `$number`
<kbd>f</kbd>                                      | Move to end and auto-scroll as new rows come in
<kbd>/</kbd>, <kbd>?</kbd>                        | Search, reverse-search for string
<kbd>n</kbd>, <kbd>N</kbd>                        | Jump to next, previous match
<kbd>q</kbd>/<kbd>Esc</kbd>                       | Quit

## Comparison to other tools

Tool                             | Functionality                      | Filetypes               | Loads whole file into memory | Streaming 
---------------------------------|------------------------------------|-------------------------|------------------------------|-----------
tass                             | ⭐ Viewing data, basic searching   | CSV, parquet            | no 😌                        | ✔️ 
[csvlens]                        | ⭐ Similar to tass                 | CSV, TSV                | no 😌                        | ✔️ 
[VisiData]                       | ⭐⭐ Summary stats, plots, etc.    | CSV, parquet, JSON, ... | yes 😱                       | ✔️ 
Excel/Calc/Numbers/Google Sheets | ⭐⭐⭐ It's a spreadsheet!         | CSV, xls, ods, ...      | yes 😱                       |

My advice is to use the most full-featured tool you can get away with.
However, if you _are_ cursed with multi-gigabyte CSV files, then your options
are limited.

[VisiData]: https://www.visidata.org/
[csvlens]: https://github.com/YS-L/csvlens

## Tips & tricks

Here are some more tips for working with large CSV files:

* If you want to see summary statistics but don't care about the underlying
  data itself, you can still use VisiData/Excel/etc.: just downsample it first.
  This will reduce the precision of your stats and plots, but not the overall
  shape (probably).  [xsv] has a subcommand that can do this for you.
* If you want exact answers to complex questions, consider dumping your CSV
  into a sqlite database and working with that instead.
* For ad-hoc computations on CSV files, take a look at [frawk] - it's
  really nice.

[xsv]: https://github.com/BurntSushi/xsv
[frawk]: https://github.com/ezrosent/frawk