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