Set Scatter Plot Legend Labels With Legend_elements

I just upgraded matplotlib to version 3.1.1 and I am experimenting with using legend_elements. I am making a scatterplot of the top two components from PCA on a dataset of 30,000 f

Solution 1:

Solution Thanks to ImportanceOfBeingErnest

• .legend_elements returns legend handles and labels for a PathCollection.
  • handles = scatter.legend_elements(num=[0,1,2,3])[0] because the handles are the first object returned by the method.
• Also see Scatter plots with a legend

group_codes = {k:idx for idx, k in enumerate(fake_df.Group.unique())}
fake_df['colors'] = fake_df['Group'].apply(lambda x: group_codes[x])
fig, ax = plt.subplots(figsize=(8,8))
scatter = ax.scatter(fake_data[:,0], fake_data[:,1], c=fake_df['colors'])

handles = scatter.legend_elements(num=[0,1,2,3])[0]  # extract the handles from the existing scatter plot

ax.legend(title='Group\nCodes', handles=handles, labels=group_codes.keys())
plt.show()