TranslateProject/sources/tech/20200609 Style your data plots in Python with Pygal.md

[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Style your data plots in Python with Pygal)
[#]: via: (https://opensource.com/article/20/6/pygal-python)
[#]: author: (Shaun Taylor-Morgan https://opensource.com/users/shaun-taylor-morgan)

Style your data plots in Python with Pygal
======
An introduction one of the more stylish Python plotting libraries.
![Python in a coffee cup.][1]

[Python][2] is full of libraries that can visualize data. One of the more interactive options comes from Pygal, which I consider the library for people who like things to look good. It generates beautiful SVG (Scalable Vector Graphics) files that users can interact with. SVG is a standard format for interactive graphics, and it can lead to rich user experiences with only a few lines of Python.

### Using Pygal for stylish Python plots

In this introduction, we want to recreate this multi-bar plot, which represents the UK election results from 1966 to 2020:

![Pygal plot][3]

Before we go further, note that you may need to tune your Python environment to get this code to run, including the following. 

  * Running a recent version of Python (instructions for [Linux][4], [Mac][5], and [Windows][6])
  * Verify you're running a version of Python that works with these libraries



The data is available online and can be imported using pandas:


```
import pandas as pd
df = pd.read_csv('<https://anvil.works/blog/img/plotting-in-python/uk-election-results.csv>')
```

Now we're ready to go. The data looks like this:


```
        year  conservative  labour  liberal  others
0       1966           253     364       12       1
1       1970           330     287        6       7
2   Feb 1974           297     301       14      18
..       ...           ...     ...      ...     ...
12      2015           330     232        8      80
13      2017           317     262       12      59
14      2019           365     202       11      72
```

 

Plotting this in Pygal builds up in a way that I find easy to read. First, we define the style object in a way that will simplify our bar chart definition. Then we pass the custom style along with other metadata to a `Bar` object:


```
import pygal
from pygal.style import Style

custom_style = Style(
    colors=('#0343df', '#e50000', '#ffff14', '#929591'),
    font_family='Roboto,Helvetica,Arial,sans-serif',
    background='transparent',
    label_font_size=14,
)

c = pygal.Bar(
    title="UK Election Results",
    style=custom_style,
    y_title='Seats',
    width=1200,
    x_label_rotation=270,
)
```

Then, we `add` our data into the `Bar` object:


```
c.add('Conservative', df['conservative'])
c.add('Labour', df['labour'])
c.add('Liberal', df['liberal'])
c.add('Others', df['others'])

c.x_labels = df['year']
```

Finally, we save the plot as an SVG file:


```
`c.render_to_file('pygal.svg')`
```

The result is an interactive SVG plot you can see in this gif:

![The Python pygal library can generate rich SVG files as seen here][7]

Beautifully simple, and with beautiful results.

### Conclusion

Some plotting options in Python require building every object in great detail, and Pygal gives you that functionality from the start. Give Pygal a go if you have data on hand and you want to make a clean, beautiful, and simple plot for user interaction.

\---

_This article was first shared [here][8] and is edited and republished with permission._

--------------------------------------------------------------------------------

via: https://opensource.com/article/20/6/pygal-python

作者：[Shaun Taylor-Morgan][a]
选题：[lujun9972][b]
译者：[译者ID](https://github.com/译者ID)
校对：[校对者ID](https://github.com/校对者ID)

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[a]: https://opensource.com/users/shaun-taylor-morgan
[b]: https://github.com/lujun9972
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/coffee_python.jpg?itok=G04cSvp_ (Python in a coffee cup.)
[2]: https://opensource.com/article/20/4/plot-data-python
[3]: https://opensource.com/sites/default/files/uploads/pygal_1.png (Pygal plot)
[4]: https://opensource.com/article/20/4/install-python-linux
[5]: https://opensource.com/article/19/5/python-3-default-mac
[6]: https://opensource.com/article/19/8/how-install-python-windows
[7]: https://opensource.com/sites/default/files/uploads/pygal-interactive_3.gif (The Python pygal library can generate rich SVG files as seen here)
[8]: https://anvil.works/blog/plotting-in-pygal