Basic Lollipop Plot

logo of a chart:Lollipop

This post aims to explain how to draw a basic lollipop plot with matplotlib.

A basic lollipop plot can be created using the stem() function of matplotlib. This function takes x axis and y axis values as an argument. x values are optional; if you do not provide x values, it will automatically assign x positions.

# libraries
import matplotlib.pyplot as plt
import numpy as np
# create data
# stem function
plt.stem(x, values)
plt.ylim(0, 1.2)
# stem function: If x is not provided, a sequence of numbers is created by python:

If you have one numerical and one categorical variable, you can still draw a lollipop plot. In this case, it will be similar to a barplot. Ordering your groups and displaying the plot horizontally will give you a better looking chart. The stem() function does not allow to make it horizontal, so you can use the hline() and the plot() functions for this purpose as follow.

# libraries
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

# Create a dataframe
df = pd.DataFrame({'group':list(map(chr, range(65, 85))), 'values':np.random.uniform(size=20) })
# Reorder it based on the values:
ordered_df = df.sort_values(by='values')
# Make the plot
plt.xticks( my_range, ordered_df['group'])
# Horizontal version
plt.hlines(y=my_range, xmin=0, xmax=ordered_df['values'], color='skyblue')
plt.plot(ordered_df['values'], my_range, "D")
plt.yticks(my_range, ordered_df['group'])

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