order bar charts

[gcamargo1]

Hi!
I have a question on ordering bar plots. For example:

http://pythonplot.com/#bar-counts

(ggplot(mpg) +
aes(x='manufacturer') +
geom_bar(size=20) +
coord_flip() +
ggtitle('Number of Cars by Make')
)

how to order by "mpg" ?
Thanks!

[has2k1]

If the x mapping is an ordered categorical, it is respected.

from plydata import *
from plotnine import *
from plotnine.data import mpg

# count the manufacturer and sort by the count (see, plydata documentation
# or find out how to do the same thing using raw pandas)
m_categories = (
    mpg
    >> count('manufacturer', sort=True)
    >> pull('manufacturer')
)

df = mpg.copy()
df['manufacturer'] = pd.Categorical(df['manufacturer'], categories=m_categories, ordered=True)

(ggplot(df) + 
   aes(x='manufacturer') +
   geom_bar(size=20) + 
   coord_flip() +
   ggtitle('Number of Cars by Make')
)

[Steve-Fry]

I spent an embarrassing amount of time trying to find the solution to this today. Also based from reading around some of the other plotting packages this seems a common problem.

Is there anywhere in the docs this could be highlighted a bit more clearly?

Also as a newcomer to Plotnine, this is an awesome tool you have put together! Thanks!

[has2k1]

@Steve-Fry, what parts of the docs did you reach for?

[Steve-Fry]

In fairness it is probably mostly about me being inexperienced in pandas/plotnine, rather than a deficiency.

I checked;
https://github.com/has2k1/plotnine-examples
https://plotnine.readthedocs.io/en/stable/api.html
https://plotnine.readthedocs.io/en/stable/tutorials.html

If it would be helpful I could look at writing a demo for the examples repo?

[has2k1]

I thought of putting a note at aes but a demo would be more illustrative.

Just follow the conventions used at https://github.com/has2k1/plotnine-examples/tree/master/plotnine_examples/tutorials. i.e

• filename that starts with miscellaneous-
• # Title at the top of the notebook

Then it will be picked up when the documentation is built.

Thanks.

[Steve-Fry]

I added a new notebook and created a PR. I'm hoping I went about it in the right way, lemme know what I'm missing.

Thanks 👍

[Akaban]

Hello,

I would like to reopen this issue, I don't think it's really user friendly to not include automatic sorting in geom_bar function. If I understand correctly we need to make a pandas.Categorical each time we want to define the order of our graph. That's something I find really painful.

Can't we implement a keyword_argument sort_by="xxxx" in geom_bar?

I can do the MR if it's not too much complicated, I don't know plotnine code as of now :)

Thanks for the answer