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Lernen Thematic and Choropleth Mapping | Visualization and Applied Geospatial Analysis
Geospatial Data Science with Python

bookThematic and Choropleth Mapping

Thematic mapping is a powerful technique in geospatial data science that enables you to visually communicate patterns and relationships in attribute data across geographic regions. Unlike general reference maps, which focus on showing physical features or boundaries, thematic maps are designed to highlight a specific subject or theme, such as population density, land use, or climate zones. Among the most widely used types of thematic maps are choropleth maps, which represent data variation by shading or coloring areas—such as countries, states, or districts—according to the values of a particular attribute.

Choropleth maps provide a straightforward way to visualize how a variable changes across space. Each area on the map is colored based on the value of a selected attribute, usually using a continuous or sequential color scale. This approach makes it easy to spot spatial trends, clusters, and outliers in the data. For example, you might use a choropleth map to display population by region, where darker shades indicate higher population counts and lighter shades indicate lower ones.

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import geopandas as gpd import matplotlib.pyplot as plt # Your hosted GeoJSON world_url = "https://staging-content-media-cdn.codefinity.com/courses/6fe97724-da29-4079-ab74-75a30eeb43d3/data/world_countries.geojson" # Load dataset world = gpd.read_file(world_url) # Dissolve by CONTINENT and sum POP_EST regions = world.dissolve(by="CONTINENT", aggfunc="sum")[["POP_EST", "geometry"]] # Plot choropleth fig, ax = plt.subplots(figsize=(10, 6)) regions.plot( column="POP_EST", cmap="Blues", linewidth=0.8, edgecolor="0.8", legend=True, ax=ax ) ax.set_title("Population by Continent (Choropleth Map)", fontsize=14) ax.axis("off") plt.show()
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Use intuitive color schemes
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Choose color ramps that reflect the nature of your data. Sequential schemes (light to dark) work well for ordered data like population or income; diverging schemes are useful for data with a meaningful midpoint.

Avoid misleading colors
expand arrow

Do not use colors that imply meaning not present in the data (for example, red for "danger" unless appropriate).

Choose appropriate class breaks
expand arrow

Use statistical methods (like quantiles or natural breaks) to divide data into classes, ensuring patterns are visible and not distorted.

Always include a clear legend
expand arrow

A well-designed legend helps viewers interpret color values correctly and improves map readability.

Consider colorblind-friendly palettes
expand arrow

Use palettes that remain distinguishable for people with color vision deficiencies.

question mark

What is a choropleth map?

Select the correct answer

War alles klar?

Wie können wir es verbessern?

Danke für Ihr Feedback!

Abschnitt 3. Kapitel 2

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Suggested prompts:

What are some common mistakes to avoid when creating choropleth maps?

Can you explain the difference between a choropleth map and other types of thematic maps?

How can I choose an appropriate color scale for my choropleth map?

bookThematic and Choropleth Mapping

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Thematic mapping is a powerful technique in geospatial data science that enables you to visually communicate patterns and relationships in attribute data across geographic regions. Unlike general reference maps, which focus on showing physical features or boundaries, thematic maps are designed to highlight a specific subject or theme, such as population density, land use, or climate zones. Among the most widely used types of thematic maps are choropleth maps, which represent data variation by shading or coloring areas—such as countries, states, or districts—according to the values of a particular attribute.

Choropleth maps provide a straightforward way to visualize how a variable changes across space. Each area on the map is colored based on the value of a selected attribute, usually using a continuous or sequential color scale. This approach makes it easy to spot spatial trends, clusters, and outliers in the data. For example, you might use a choropleth map to display population by region, where darker shades indicate higher population counts and lighter shades indicate lower ones.

1234567891011121314151617181920212223242526
import geopandas as gpd import matplotlib.pyplot as plt # Your hosted GeoJSON world_url = "https://staging-content-media-cdn.codefinity.com/courses/6fe97724-da29-4079-ab74-75a30eeb43d3/data/world_countries.geojson" # Load dataset world = gpd.read_file(world_url) # Dissolve by CONTINENT and sum POP_EST regions = world.dissolve(by="CONTINENT", aggfunc="sum")[["POP_EST", "geometry"]] # Plot choropleth fig, ax = plt.subplots(figsize=(10, 6)) regions.plot( column="POP_EST", cmap="Blues", linewidth=0.8, edgecolor="0.8", legend=True, ax=ax ) ax.set_title("Population by Continent (Choropleth Map)", fontsize=14) ax.axis("off") plt.show()
copy
Use intuitive color schemes
expand arrow

Choose color ramps that reflect the nature of your data. Sequential schemes (light to dark) work well for ordered data like population or income; diverging schemes are useful for data with a meaningful midpoint.

Avoid misleading colors
expand arrow

Do not use colors that imply meaning not present in the data (for example, red for "danger" unless appropriate).

Choose appropriate class breaks
expand arrow

Use statistical methods (like quantiles or natural breaks) to divide data into classes, ensuring patterns are visible and not distorted.

Always include a clear legend
expand arrow

A well-designed legend helps viewers interpret color values correctly and improves map readability.

Consider colorblind-friendly palettes
expand arrow

Use palettes that remain distinguishable for people with color vision deficiencies.

question mark

What is a choropleth map?

Select the correct answer

War alles klar?

Wie können wir es verbessern?

Danke für Ihr Feedback!

Abschnitt 3. Kapitel 2
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