Line Plot
When to use line plots
Line plots are best for:
- Trends over time
- Comparing changes across periods
A line plot is Matplotlib’s default: plt.plot(data)plt.plot(data) alone draws a line, connecting
each point to the next in the order the data appears. Points aren’t interpolated by
magic — Matplotlib just draws straight segments between consecutive (x, y)(x, y) pairs,
so ordering your data matters.
flowchart LR A["x values"] --> C["plt.plot(x, y)"] B["y values"] --> C C --> D["marker + linestyle"] D --> E["title / xlabel / ylabel"] E --> F["legend (if multiple series)"]
Basic line plot
Line plot
import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [120, 140, 130, 160, 155]
plt.figure(figsize=(7, 4))
plt.plot(x, y, marker="o")
plt.title("Orders over time")
plt.xlabel("Day")
plt.ylabel("Orders")
plt.grid(True, alpha=0.3)
plt.tight_layout()
plt.show()Line plot
import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [120, 140, 130, 160, 155]
plt.figure(figsize=(7, 4))
plt.plot(x, y, marker="o")
plt.title("Orders over time")
plt.xlabel("Day")
plt.ylabel("Orders")
plt.grid(True, alpha=0.3)
plt.tight_layout()
plt.show()Multiple lines
Multiple lines
import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y1 = [120, 140, 130, 160, 155]
y2 = [100, 110, 120, 125, 140]
plt.figure(figsize=(7, 4))
plt.plot(x, y1, label="Product A")
plt.plot(x, y2, label="Product B")
plt.title("Orders over time")
plt.xlabel("Day")
plt.ylabel("Orders")
plt.legend()
plt.grid(True, alpha=0.3)
plt.tight_layout()
plt.show()Multiple lines
import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y1 = [120, 140, 130, 160, 155]
y2 = [100, 110, 120, 125, 140]
plt.figure(figsize=(7, 4))
plt.plot(x, y1, label="Product A")
plt.plot(x, y2, label="Product B")
plt.title("Orders over time")
plt.xlabel("Day")
plt.ylabel("Orders")
plt.legend()
plt.grid(True, alpha=0.3)
plt.tight_layout()
plt.show()Visualize it
Watch a line plot draw itself point by point — each new value connects to the previous one with a straight segment:
Tip
If lines cross and the plot becomes confusing, consider faceting (multiple subplots) or focusing on fewer series.
Next
Continue to Bar Chart and Horizontal Bar to compare categories instead of trends.
🧪 Try It Yourself
Exercise 1 – Plot with a marker
Exercise 2 – Label a series for the legend
Exercise 3 – Step drawstyle
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