CODEWITHSUNDEEP
pandasmatplotlibplotgroup-by
SANM2009
SANM2009

Reputation: 1998

Pandas loop over groupby and plot each group

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([['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.val1.plot.line(ax=ax1, ylim=[5,20], color='red',x=group.year)
  ax1.set_ylabel('val1')
  ax2 = ax1.twinx()
  group.val2.plot.line(ax=ax2, ylim=[5,20], color='blue' ,x=group.year)
  ax2.set_ylabel('val2')
  plt.title(str(name), fontsize=15);

It seems I'm close, but just there are some issues some where.

  1. First issue is that there are 5 groups in the groupby object. I get the 5 figures as I want, but only first one has the plots(lines) on it. Others figures are blank with the correct title on them, any idea what is wrong with my code?
  2. How can I set a group column / key as the x axis, I have tried this x=group.desiredx but it doesn't do anything.

mykey| year| val1| val2
item1| 2000| 5| 34
item2| 2001| 45| 34
item3| 2002| 34| 34
item1| 2000| 22| 65
item2| 2001| 34| 54
item3| 2002| 12| 54
item1| 2000| 23| 54
item2| 2001| 34| 34
item3| 2002| 21| 21

Upvotes: 2

Views: 6972

Answers (2)

SANM2009
SANM2009

Reputation: 1998

Thanks to ImportanceOfBeingErnest, I have got the result what I wanted. Here is full tweaked version of the code, for anyone who may need it in future. I have added legend = False, without this val1 and val2 are written on top of each other and looks messy. 

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',2001,3, 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", legend 
  = False, xticks = [2000,2001,2002])
  ax1.set_ylabel('val1  ssssssss')
  ax2 = ax1.twinx()
  group.plot.line(ax=ax2, ylim=[0,3], color='blue',x="year",y="val2", legend 
  = False, xticks = [2000,2001,2002])
  ax2.set_ylabel('val2 dddddd')
  plt.title(str(name), fontsize=15)

   plt.show()

Upvotes: 0

ImportanceOfBeingErnest
ImportanceOfBeingErnest

Reputation: 339140

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()

Upvotes: 1

Related Questions