How to iteratively plot to the correct subplot axes

Question

Let's say I have two dataframes:

a = pd.DataFrame({"A": [2,3,4,5], 
                  "B": [4,8,9,10], 
                  "C" :[63,21,23,4],
                  "D": [56,32,12,2]
                 })

b = pd.DataFrame({"A": [12,13,14,15], 
                  "B": [41,81,91,10], 
                  "C": [3,2,5,6], 
                  "D": [4,2,3,4]
                 })

I want to be able to plot scatterplots between the variables on each dataframe with the same name. I've come up with the following code:

fig, ax = plt.subplots((round(len(b)/2)),2,figsize=(10,10))
for i, col in enumerate(b.columns):

    sns.regplot(x=a[col], y=b[col], ax=ax[i,0])
    plt.title(col)
    sns.regplot(x=a[col], y=b[col], ax = ax[i,1])
    plt.title(col)


plt.tight_layout()

However, this yields the following figure:

What I want is:

I know this will be simple, but I just can't figure out a way of looping for the second ax[i,1]. Many thanks!

Answer 1

• ax is a numpy array, so it's easier to use .ravel, which flattens the array and makes it easier to index
  • ax, in the OP, is a (2, 2) array, which .ravel flattens to (4,).
• See the following SO questions for additional details regarding subplot axes arrays:
  • How to fix 'numpy.ndarray' object has no attribute 'get_figure' when plotting subplots
  • How to resolve AttributeError: 'numpy.ndarray' object has no attribute 'get_figure' when plotting subplots [duplicate]

fig, ax = plt.subplots((round(len(b)/2)), 2,figsize=(10,10))
v = ax.ravel()
for i, col in enumerate(b.columns):

    sns.regplot(x=a[col], y=b[col], ax=v[i])
    v[i].set_xlabel(f'{col}_a')
    v[i].set_ylabel(f'{col}_b')
    v[i].set_title(col)

plt.tight_layout()