Pandas loop over groupby and plot each group

Question

I am trying to loop over a groupby object and plot each group. But I am having some issues. Can someone please tell me where I am going wrong?

df = pd.DataFrame(         


        

Answer 1

The values to plot on the y axis are 1 and 2. You set the ylim to something bigger than 5, ylim=[5,20]. Hence you do not see the values at 1 and 2.

Setting the ylim to some reasonable numbers, e.g. ylim=[0,3] will allow you to see the data.

Also, group.val1.plot will plot the data against its index, because there is no "year" in group.val1. Instead take "val1" as the y value.

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame([['item1',2000,1, 2], ['item1',2001,1, 2], ['item1',2002,1, 2], 
              ['item2',2000,1, 2], ['item2',2001,1, 2], ['item2',2002,1, 2]],
              columns=['mykey', 'year','val1','val2'])

grouped = df.groupby('mykey')
for name,group in grouped:
  fig = plt.figure()
  ax1 = fig.add_subplot(111)
  group.plot.line(ax=ax1, ylim=[0,3], color='red',x="year",y="val1")
  ax1.set_ylabel('val1')
  ax2 = ax1.twinx()
  group.plot.line(ax=ax2, ylim=[0,3], color='blue',x="year",y="val2")
  ax2.set_ylabel('val2')
  plt.title(str(name), fontsize=15)

plt.show()