How can I implement plt.subplot correctly so my graphs can be side by side?

Question

I am outputting two scatter plots, but I want both graphs to be next to each other side by side.

When I use plt.subplots, my ax1 and ax2 aren’t being recognized? How can I make the bottom two scatterplots next to each other? Whenever I use plt.subplots it just creates empty graphs.

# Scatter plots.
ax1 = df_Baker.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(10, 7))
df_Muriel.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(10, 7), ax=ax1)
df_Tanner.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(10, 7), ax=ax1)


# regression lines
plt.plot(df_Baker.HS_GPA, Baker_fit[0] * df_Baker.HS_GPA + Baker_fit[1], color='darkblue', linewidth=2)
plt.plot(df_Tanner.HS_GPA, Tanner_fit[0] * df_Tanner.HS_GPA + Tanner_fit[1], color='deeppink', linewidth=2)
plt.plot(df_Muriel.HS_GPA, Muriel_fit[0] * df_Muriel.HS_GPA + Muriel_fit[1], color='deeppink', linewidth=2)



plt.legend(labels=['_h', '_hii', '_', '10 - 20','1 - 5'], title='Legend Test')


plt.title('BIO: Basic Concepts', size=24)
plt.xlabel('High school gpa', size=18)
plt.ylabel('cousre Grade', size=18);

#-----------------------------------------------------------------------------


# Scatter plots.
ax2 = df_Baker.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(6, 3))
df_Muriel.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(6, 3), ax=ax2)
df_Tanner.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(6, 3), ax=ax2)


# regression lines
plt.plot(df_Baker.HS_GPA, Baker_fit[0] * df_Baker.HS_GPA + Baker_fit[1], color='black', linewidth=2)
plt.plot(df_Tanner.HS_GPA, Tanner_fit[0] * df_Tanner.HS_GPA + Tanner_fit[1], color='black', linewidth=2)
plt.plot(df_Muriel.HS_GPA, Muriel_fit[0] * df_Muriel.HS_GPA + Muriel_fit[1], color='black', linewidth=2)


plt.legend(labels=['_h', '_hii', '_', '10 - 20','1 - 5'], title='Legend Test')


plt.title('BIO: Basic Concepts', size=24)
plt.xlabel('High school gpa', size=18)
plt.ylabel('cousre Grade', size=18);

Output graphs so far

Asked By: Aztec619

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Source

Answer 1

In this line:

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(10, 3))

your create the two axes objects and attach the names ax1 and ax2 to them.

Later, in

ax1 = df_Baker.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(10, 7))

(and similarely in the line for ax2), your create new axis objects, and assign the names ax1 and ax2 to them.

I seems that this is not what you want. Rather, I guess you want to use the previously generated axes objects in the calls to df.Bakker.plot(). You can achieve this by using the ax= keyword:

df_Baker.plot(kind='scatter', x='HS_GPA', y='Course_Grade', color='black', alpha=0.5, figsize=(10, 7), ax=ax1)

You will also have to change the plt.plot(...) calls to ax1.plot(...) or ax2.plot(...), and similar for the functions plt.xlabel, plt.ylabel, plt.legend.

I would suggest to read the Blog post https://matplotlib.org/matplotblog/posts/pyplot-vs-object-oriented-interface/ on the difference between the Pyplot vs. Object Oriented Interface to Matplotlib, and you can also have a look at the examples referenced in https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.subplots.html

Answered By: Hansemann

How can I implement plt.subplot correctly so my graphs can be side by side?

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