Adjust height of subplot with 1 row and 2 columns-CodePudding

I want to create two plots, with the second plot generally being about 1/2 or less the size of the main plot. However, when trying to do this with one row and two columns I get an error

fig, axs=plt.subplots(1,2, figsize=(12,10), gridspec_kw={'height_ratios': [2,1],
                                                        'width_ratios':[3,1]})

(ValueError: Expected the given number of height ratios to match the number of rows of the grid).

If I only put in one argument in the list for height ratios then I get two plots that are of the same size.

fig, axs=plt.subplots(1,2, figsize=(12,10), gridspec_kw={'height_ratios': [3],
                                                        'width_ratios':[3,1]})

That plot is shown below. How can I make the plot on the right half the size of the one on the left, while placing it in the bottom right (not top right)?

CodePudding user response：

The trick here is that height_ratios depends on the number of rows. A ratio is a relationship between 2 things so you cannot introduce a ratio between height subplots if there is only one row (aka one 'height' for the subplots) - no matter how many columns there are. However, you can trick plt.subplots using fig.add_gridspec to introduce more rows and columns but never call on them. Here is how you can go about it:

import matplotlib.pyplot as plt

if __name__ == "__main__":

    fig = plt.figure(figsize=(12, 10))
    gs = fig.add_gridspec(nrows=2, ncols=2, width_ratios=[3, 1])

    fig.suptitle('An overall title')

    # Add left subplot
    # gs[top and bottom rows, first column (the 'left' subplot))]
    ax_left = fig.add_subplot(gs[:, 0])
    ax_left.set_xlabel("Left X label")
    ax_left.set_ylabel("Left Y label")

    # Add bottom right subplot - gs[bottom row, last column (the 'left' subplot)]
    # We do not add the upper right subplot
    ax_right_bottom = fig.add_subplot(gs[-1, -1])
    ax_right_bottom.set_xlabel("Right Bottom X label")
    ax_right_bottom.set_ylabel("Right Bottom Y label")

    plt.tight_layout()
    plt.show()

If you wanted to make the bottom right subplot smaller or bigger in relation to the left subplot, now you could use height_ratios because now there are two rows and you can implement a ratio.

You can read more about it in Arranging multiple Axes in a Figure - it's full of useful tips for wrangling axes and subplots. Cheers!