<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">
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;
new rows 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
<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
tass | ⭐ Viewing data, basic searching and filtering | CSV, parquet | yes | Large (bigger than memory is fine)
[csvlens] | ⭐ Appears to be very similar to tass | CSV, TSV | yes | ?
[VisiData] | ⭐⭐ Summary stats, plots, etc. | CSV, JSON, parquet, ... | yes | Medium (up to perhaps 50% of memory)
Excel/Calc/Numbers/Google Sheets | ⭐⭐⭐ It's a spreadsheet! | CSV, xls, ods, ... | no | Small (1M row limit)
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
