How To Merge/Combine Two Plots in Python Pandas

DataPlotPlus -

If you need to merge or combine two plots into single one in Pandas/Python you can use subplots. We will show two different examples:

  • combine scatter and line plot
  • merge two plots vertically

Steps to combine plots with Pandas

  • Creates a dummy DataFrame (df) with random "data"
  • Groups data by "date" and calculates the mean for each group.
  • Creates columns with mean values (adjusted by +30% and -30%)
  • Generates a scatter plot df.plot.scatter()
  • Overlays a line plot on the same subplot with aggregated data df_agg.plot()
  • Displays the combined plots using plt.show().

Data

date real_exe_time
14 A 65
20 A 78
19 A 23
28 A 81
10 A 77

Example - single plot

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

n=30
df = pd.DataFrame({"date": np.random.choice(list("ABCDEF"), n), "real_exe_time": np.random.randint(1, 100, n)})
df = df.sort_values(by="date").reindex()

df_agg = df.groupby("date")["real_exe_time"].agg(mean="mean").reset_index()
df_agg["mean+30%"] = df_agg["mean"] * 1.3
df_agg["mean-30%"] = df_agg["mean"] * 0.7

ax = df.plot.scatter(x = 'date', y = 'real_exe_time')
df_agg.plot(x='date', y=['mean','mean+30%','mean-30%'], ax=ax)

plt.show()

Output - combined output veritically

Example

import numpy as np
import matplotlib.pyplot as plt

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

x = np.linspace(-10, 10, 100)
y1 = x**2
y2 = 2 * x + 5

# Subplot for individual plots
plt.subplot(211)
plt.plot(x, y1, color='blue', lw=3, label='x^2')
plt.plot(x, y2, color='green', lw=3, label='2x + 5')
plt.legend()

# Extracting data from the line plots
X, Y = [], []
for lines in plt.gca().get_lines():
    for x, y in lines.get_xydata():
        X.append(x)
        Y.append(y)

# Sorting the extracted data
idx = np.argsort(X)
X = np.array(X)[idx]
Y = np.array(Y)[idx]

# Merged plot
plt.subplot(212)
plt.bar(X, Y, color='purple', alpha=0.7, width=0.5)

plt.show()

Below you can find the steps to combine two different plots into single one with Pandas:

  • Uses x values from -10 to 10.
  • Generates y1 as x^2 and y2 as 2x + 5.
  • First subplot (plt.subplot(211)) for individual line plots.
  • Plots y1 (blue line) and y2 (green line) with different labels.
  • Extracts data points (X and Y) from the individual line plots.
  • Sorts extracted data points based on X values.
  • Second subplot (plt.subplot(212)) for a merged bar plot.
  • Plots the sorted data as a bar plot (purple bars) in the second subplot.
  • Displays the combined plot using plt.show().

Output

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