Format y axis as percent
This is a few months late, but I have created PR#6251 with matplotlib to add a new PercentFormatter
class. With this class you just need one line to reformat your axis (two if you count the import of matplotlib.ticker
):
import ...
import matplotlib.ticker as mtick
ax = df['myvar'].plot(kind='bar')
ax.yaxis.set_major_formatter(mtick.PercentFormatter())
PercentFormatter()
accepts three arguments, xmax
, decimals
, symbol
. xmax
allows you to set the value that corresponds to 100% on the axis. This is nice if you have data from 0.0 to 1.0 and you want to display it from 0% to 100%. Just do PercentFormatter(1.0)
.
The other two parameters allow you to set the number of digits after the decimal point and the symbol. They default to None
and '%'
, respectively. decimals=None
will automatically set the number of decimal points based on how much of the axes you are showing.
Update
PercentFormatter
was introduced into Matplotlib proper in version 2.1.0.
Jianxun's solution did the job for me but broke the y value indicator at the bottom left of the window.
I ended up using FuncFormatter
instead (and also stripped the uneccessary trailing zeroes as suggested here):
import pandas as pd
import numpy as np
from matplotlib.ticker import FuncFormatter
df = pd.DataFrame(np.random.randn(100,5))
ax = df.plot()
ax.yaxis.set_major_formatter(FuncFormatter(lambda y, _: '{:.0%}'.format(y)))
Generally speaking I'd recommend using FuncFormatter
for label formatting: it's reliable, and versatile.
pandas dataframe plot will return the ax
for you, And then you can start to manipulate the axes whatever you want.
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randn(100,5))
# you get ax from here
ax = df.plot()
type(ax) # matplotlib.axes._subplots.AxesSubplot
# manipulate
vals = ax.get_yticks()
ax.set_yticklabels(['{:,.2%}'.format(x) for x in vals])