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Using this code to plot the iris dataset gives me an extra empty plot:

import pandas as pd
from matplotlib import pyplot as plt

d = {'Species': ['setosa', 'versicolor','virginica'], 'Sepal length': [1, 2, 3], 'Sepal width': [2, 4, 6]}

df = pd.DataFrame(data=d)


unv = df['Species'].unique()
colorv = ['r','b','g']
markerv = ['v', 'o', '>']


#Getting an extra empty plot for no reason
fig, ax=plt.subplots(1,2)
for i in range(len(unv)):
    df[df['Species'] == unv[i]].plot(x="Sepal length", y="Sepal width", kind="scatter",ax=ax[0],label=unv[i],color=colorv[i], marker = markerv[i])

plt.show()

Any suggestions why I receive this extra plot and how I can remove it? enter image description here

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  • fig, ax=plt.subplots(1,2) is creating 2 axes (plots). If unv has only one element, then you get only one iteration and one plot. Try to print len(unv). If this is not it, check if one of the elements is not empty. A way to avoid the first issue is to do: fig, ax = plt.subplots(1, len(unv)). Commented Jul 24, 2018 at 11:05
  • Hmm..does not quite work. The length of unv is 3, and thus I get 3 plots Commented Jul 24, 2018 at 11:37
  • 1
    You need to understand that we can't reproduce your example. So you have 3 elements in unv, as I could have guess with the use of 3 colors and markers. Thus why are you creating only 2 axes? Did you check the data you are trying to plot (iris[iris['Species'] == unv[i]])? Commented Jul 24, 2018 at 11:53
  • why do you have subplots(1,2)? your code looks like you want to plot everything on the same axes Commented Jul 24, 2018 at 12:06
  • I want only 1 plot, but if I go for fig, ax=plt.subplots(1,1) I get an error. And yes, data iris[iris['Species'] == unv[i]]) is alright Commented Jul 24, 2018 at 12:10

1 Answer 1

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You are getting 2 subplots because you are requesting two subplots by calling plt.subplots(1,2), which creates 1*2 subplots on 1 line and 2 columns.

The answer to your question is therefore to call plt.subplots(1,1). In the comments, you say you have tried but you get an error. This is expected. The documentation states (emphasis mine):

Returns:

fig : matplotlib.figure.Figure object

ax : Axes object or array of Axes objects.

ax can be either a single matplotlib.axes.Axes object or an array of Axes objects if more than one subplot was created. The dimensions of the resulting array can be controlled with the squeeze keyword, see above.

if subplots() returns only one axes, then it returns that Axes object instead of a list, therefore you should modify your call to:

df[df['Species'] == unv[i]].plot( (...) ,ax=ax, (...) )
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