# Format y axis as percent

I have an existing plot that was created with pandas like this:

```
df['myvar'].plot(kind='bar')
```

The y axis is format as float and I want to change the y axis to percentages. All of the solutions I found use ax.xyz syntax and **I can only place code below the line above that creates the plot** (I cannot add ax=ax to the line above.)

**How can I format the y axis as percentages without changing the line above?**

Here is the solution I found **but requires that I redefine the plot** :

```
import matplotlib.pyplot as plt
import numpy as np
import matplotlib.ticker as mtick
data = [8,12,15,17,18,18.5]
perc = np.linspace(0,100,len(data))
fig = plt.figure(1, (7,4))
ax = fig.add_subplot(1,1,1)
ax.plot(perc, data)
fmt = '%.0f%%' # Format you want the ticks, e.g. '40%'
xticks = mtick.FormatStrFormatter(fmt)
ax.xaxis.set_major_formatter(xticks)
plt.show()
```

Link to the above solution: Pyplot: using percentage on x axis

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])
```

From: stackoverflow.com/q/31357611