Plotting a histogram from array

Question

Example array:

a=np.array([1,2,3,4,4,4,2,1,1,1,1])

I want to create a histogram from the array, and if I use matplotlib.pyplot's histogram:

import matplotlib.pyplot as plt
plt.hist(a,bins=[1,2,3,4,5])

I get this:

How do I get the columns in different colors? and how do i get labels, like if a green column the legend shows number 1 is green.

I suspect I might create four different datasets, but that I can't get to work..

Solution

Instead of directly calling plt.hist , try using subplot and plot a histogram inside that , like this -

import matplotlib.pyplot as plt
# define window size, output and axes
fig, ax = plt.subplots(figsize=[8,6])

# set plot title
ax.set_title("Some title")

# set x-axis name
ax.set_xlabel("X-Label")

# set y-axis name
ax.set_ylabel("Y-Label")

# create histogram within output
N, bins, patches = ax.hist(data, bins=50, color="#777777") #initial color of all bins

# Iterate through all histogram elements
# each element in this interation is one patch on the histogram, where:
# - bin_size - number of records in current bin
# - bin - value of current bin (x-axis)
# - patch - a rectangle, object of class matplotlib.patches.Patch
# more details on patch properties: [visit this link][1]
for bin_size, bin, patch in zip(N, bins, patches):
    if bin_size == <some number>:
        patch.set_facecolor("<some color like #FF000>")
        patch.set_label("something")
plt.show()