Difficulty to plot legend for a color bar in python 3.6

Question

I have 3 colors (ccc) for 3 different types of rock (d2) and I would like to plot a legend with rectangles for my color bar. I already searched about it, but couldn't find the right code. Could you help me?

import numpy as np
import pandas as pd
import matplotlib.colors as colors
import matplotlib.pyplot as plt

d = {'Porosity': [20, 5, 15, 7, 30], 'Permeability': [2500, 100, 110, 40, 
2200], 'Lithology': ['Sandstone', 'Shale', 'Shale', 'Halite', 'Sandstone'], 
'Depth': [1000, 1500, 2000, 2500, 3000]}
df = pd.DataFrame(d)

d2 = {'Sandstone': 1, 'Shale': 2, 'Halite': 3}

lito = df['Lithology']
df['Label'] = lito.map(d2)

ccc = ['darkgreen','skyblue', 'yellow']
cmap_facies = colors.ListedColormap(ccc[0:len(ccc)], 'indexed')

cluster = np.repeat(np.expand_dims(df['Label'].values, 1), 1, 1)

f, ax = plt.subplots(nrows=1, ncols=1, figsize=(2,12))

depth = df['Depth']

ax.imshow(cluster, interpolation='none', aspect='auto', cmap=cmap_facies, 
vmin=1, vmax=3, extent=[0,1 ,np.max(depth),np.min(depth)])

plt.tick_params(bottom=False, labelbottom=False)

Answer 1

If I understood correctly, you want three legend handles, one for each colored stone. This can be done by adding custom legend handles using mpatches

import numpy as np
import pandas as pd
import matplotlib.colors as colors
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches # <-- Add this import

# Your code here

hands = []
for k, col in zip(d2.keys(), ccc):
    hands.append(mpatches.Patch(color=col, label=k))
plt.legend(handles=hands, loc=(1.05, 0.5), fontsize=18)