step_5.py

plot_grid = plt.GridSpec(1, 15, hspace=0.2, wspace=0.1) # Setup a 1x15 grid
ax = plt.subplot(plot_grid[:,:-1]) # Use the leftmost 14 columns of the grid for the main plot

ax.scatter(
    x=x.map(x_to_num), # Use mapping for x
    y=y.map(y_to_num), # Use mapping for y
    s=size * size_scale, # Vector of square sizes, proportional to size parameter
    c=color.apply(value_to_color), # Vector of square colors, mapped to color palette
    marker='s' # Use square as scatterplot marker
)
# ...

# Add color legend on the right side of the plot
ax = plt.subplot(plot_grid[:,-1]) # Use the rightmost column of the plot

col_x = [0]*len(palette) # Fixed x coordinate for the bars
bar_y=np.linspace(color_min, color_max, n_colors) # y coordinates for each of the n_colors bars

bar_height = bar_y[1] - bar_y[0]
ax.barh(
    y=bar_y,
    width=[5]*len(palette), # Make bars 5 units wide
    left=col_x, # Make bars start at 0
    height=bar_height,
    color=palette,
    linewidth=0
)
ax.set_xlim(1, 2) # Bars are going from 0 to 5, so lets crop the plot somewhere in the middle
ax.grid(False) # Hide grid
ax.set_facecolor('white') # Make background white
ax.set_xticks([]) # Remove horizontal ticks
ax.set_yticks(np.linspace(min(bar_y), max(bar_y), 3)) # Show vertical ticks for min, middle and max
ax.yaxis.tick_right() # Show vertical ticks on the right