Multiple time series comparison in Matplotlib - Step-by-Step Execution

Concept Flow - Multiple time series comparison

Load data for series A

↓

Load data for series B

↓

Prepare time axis

↓

Plot series A on graph

↓

Plot series B on graph

↓

Add labels and legend

↓

Show combined plot

↓

END

Load multiple time series data, plot them on the same graph with labels and legend, then display for comparison.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
import pandas as pd

# Create two time series data
series1 = pd.Series([1, 3, 2, 5, 7], index=pd.date_range('2024-01-01', periods=5))
series2 = pd.Series([2, 4, 1, 6, 8], index=pd.date_range('2024-01-01', periods=5))

plt.plot(series1.index, series1, label='Series 1')
plt.plot(series2.index, series2, label='Series 2')
plt.legend()
plt.show()

This code plots two time series on the same graph to compare their values over the same dates.

Execution Table

Step	Action	Data/Variables	Result/Output
1	Create series1	series1 = [1,3,2,5,7] with dates 2024-01-01 to 2024-01-05	series1 ready with 5 data points
2	Create series2	series2 = [2,4,1,6,8] with same dates	series2 ready with 5 data points
3	Plot series1	x=dates, y=series1 values	Line for series1 drawn on plot
4	Plot series2	x=dates, y=series2 values	Line for series2 drawn on plot
5	Add legend	labels: Series 1, Series 2	Legend displayed on plot
6	Show plot	Combined plot with both series	Graph window opens showing both lines
7	End	All plotting done	Execution stops

💡 All time series plotted and displayed, program ends

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 6
series1	None	[1,3,2,5,7] with dates	[1,3,2,5,7] with dates	[1,3,2,5,7] with dates
series2	None	None	[2,4,1,6,8] with dates	[2,4,1,6,8] with dates
plot	Empty	Empty	Empty	Displayed plot with both lines

Key Moments - 3 Insights

Why do both series use the same date range as the x-axis?

Both series are created with the same date index, so when plotting, the x-axis aligns perfectly for comparison, as shown in execution_table steps 1 and 2.

What happens if we plot series without labels?

Without labels, the legend would be empty or missing, making it hard to tell which line is which. Step 5 shows adding labels to fix this.

Why do we call plt.show() at the end?

plt.show() displays the plot window with all lines drawn. Without it, the plot may not appear. This is shown in step 6.

Visual Quiz - 3 Questions

Look at the execution_table at step 3. What is plotted on the x-axis?

A Dates from 2024-01-01 to 2024-01-05

B Values of series1

C Values of series2

D Legend labels

💡 Hint

Check the 'Data/Variables' column at step 3 in execution_table

At which step are both series visible on the plot?

A Step 3

B Step 5

C Step 4

D Step 6

💡 Hint

Look for when series2 is plotted in execution_table

If we remove plt.legend(), what changes in the output?

A No lines will be drawn

B Plot will show but no legend labels

C Plot will not show at all

D Series data will be lost

💡 Hint

Refer to step 5 in execution_table about adding legend

Concept Snapshot

Multiple time series comparison:
- Plot multiple series on same graph using plt.plot()
- Use same x-axis (time) for alignment
- Add labels and plt.legend() for clarity
- Call plt.show() to display
- Helps visually compare trends and values

Full Transcript

This visual execution shows how to compare multiple time series using matplotlib. First, two series with the same date range are created. Then each series is plotted on the same graph with their dates on the x-axis. Labels are added for clarity, and a legend is shown. Finally, plt.show() displays the combined plot. This method helps us see how two sets of data change over time side by side.