[matplotlib] How to display multiple images in one figure correctly?

I am trying to display 20 random images on a single Figure. The images are indeed displayed, but they are overlaid. I am using:

import numpy as np
import matplotlib.pyplot as plt
w=10
h=10
fig=plt.figure()
for i in range(1,20):
    img = np.random.randint(10, size=(h,w))
    fig.add_subplot(i,2,1)
    plt.imshow(img)
plt.show()

I would like them to appear naturally in a grid layout (say 4x5), each with the same size. Part of the problem is that I do not know what the arguments to add_subplot mean. The documentation states that the arguments are the number of rows, number of columns, and plot number. There is no positioning argument. Additionally, the plot number can only be 1 or 2. How can I achieve this?

You could try the following:

import matplotlib.pyplot as plt
import numpy as np

def plot_figures(figures, nrows = 1, ncols=1):
    """Plot a dictionary of figures.

    Parameters
    ----------
    figures : <title, figure> dictionary
    ncols : number of columns of subplots wanted in the display
    nrows : number of rows of subplots wanted in the figure
    """

    fig, axeslist = plt.subplots(ncols=ncols, nrows=nrows)
    for ind,title in zip(range(len(figures)), figures):
        axeslist.ravel()[ind].imshow(figures[title], cmap=plt.jet())
        axeslist.ravel()[ind].set_title(title)
        axeslist.ravel()[ind].set_axis_off()
    plt.tight_layout() # optional



# generation of a dictionary of (title, images)
number_of_im = 20
w=10
h=10
figures = {'im'+str(i): np.random.randint(10, size=(h,w)) for i in range(number_of_im)}

# plot of the images in a figure, with 5 rows and 4 columns
plot_figures(figures, 5, 4)

plt.show()

However, this is basically just copy and paste from here: Multiple figures in a single window for which reason this post should be considered to be a duplicate.

I hope this helps.