Interactive Line Charts

Basic Line Chart

code.py

import plotly.express as px
import pandas as pd

df = pd.DataFrame({
    'Month': ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun'],
    'Sales': [100, 120, 115, 140, 160, 180]
})

fig = px.line(df, x='Month', y='Sales', title='Monthly Sales')
fig.show()

Add Markers

code.py

fig = px.line(df, x='Month', y='Sales', markers=True)
fig.show()

Multiple Lines

code.py

df = pd.DataFrame({
    'Month': ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun'],
    'Product_A': [100, 120, 115, 140, 160, 180],
    'Product_B': [80, 95, 100, 110, 130, 150]
})

# Reshape for Plotly
df_long = df.melt(id_vars='Month', var_name='Product', value_name='Sales')

fig = px.line(df_long, x='Month', y='Sales', color='Product', markers=True)
fig.show()

Line with Color Groups

code.py

df = pd.DataFrame({
    'Month': ['Jan', 'Feb', 'Mar']*2,
    'Sales': [100, 120, 115, 80, 95, 100],
    'Region': ['East', 'East', 'East', 'West', 'West', 'West']
})

fig = px.line(df, x='Month', y='Sales', color='Region', markers=True)
fig.show()

Area Chart

Fill under the line:

code.py

fig = px.area(df, x='Month', y='Sales', title='Sales Area Chart')
fig.show()

Stacked Area

code.py

fig = px.area(df_long, x='Month', y='Sales', color='Product')
fig.show()

Custom Line Style

code.py

fig = px.line(df, x='Month', y='Sales')

# Make line thicker and dashed
fig.update_traces(line=dict(width=3, dash='dash'))
fig.show()

Dash options: 'solid', 'dot', 'dash', 'longdash', 'dashdot'

Add Range Slider

code.py

fig = px.line(df, x='Month', y='Sales')
fig.update_xaxes(rangeslider_visible=True)
fig.show()

Adds a slider to zoom in on time periods!

Fill Between Lines

code.py

import plotly.graph_objects as go

months = ['Jan', 'Feb', 'Mar', 'Apr', 'May']
high = [120, 130, 125, 145, 160]
low = [80, 90, 85, 105, 120]

fig = go.Figure()
fig.add_trace(go.Scatter(x=months, y=high, name='High', line=dict(color='green')))
fig.add_trace(go.Scatter(x=months, y=low, name='Low', fill='tonexty', line=dict(color='red')))
fig.show()

Complete Example

code.py

import plotly.express as px
import pandas as pd

# Stock-like data
df = pd.DataFrame({
    'Date': pd.date_range('2024-01-01', periods=30),
    'Stock_A': [100 + i + (i % 5) for i in range(30)],
    'Stock_B': [80 + i*0.8 + (i % 3) for i in range(30)]
})

df_long = df.melt(id_vars='Date', var_name='Stock', value_name='Price')

fig = px.line(df_long, x='Date', y='Price', color='Stock',
              title='Stock Price Comparison',
              markers=True)

fig.update_xaxes(rangeslider_visible=True)
fig.show()

Key Points

px.line() for line charts
markers=True shows data points
color creates multiple lines
px.area() fills under line
rangeslider_visible adds zoom slider
Use melt() to reshape data for multiple lines

What's Next?

Learn to create interactive bar charts.