A13b Checkpoint

Import libraries¶

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import ee
import geemap

import ee import geemap

Create an interactive map¶

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Map = geemap.Map(center=[40, -100], zoom=4)

Map = geemap.Map(center=[40, -100], zoom=4)

Add Earth Engine Python script¶

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# Add Earth Engine dataset
image = ee.Image("USGS/SRTMGL1_003")

#  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#  Chapter:      A1.3 Built Environments
#  Checkpoint:   A13b
#  Author:       Erin Trochim
#  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Import roads data.
grip4_africa = ee.FeatureCollection(
        'projects/sat-io/open-datasets/GRIP4/Africa'),
    grip4_north_america = ee.FeatureCollection(
        'projects/sat-io/open-datasets/GRIP4/North-America'),
    grip4_europe = ee.FeatureCollection(
        'projects/sat-io/open-datasets/GRIP4/Europe')

# Check the roads data sizes.
print('Grip4 Africa size', grip4_africa.size())
print('Grip4 North America size', grip4_north_america.size())
print('Grip4 Europe size', grip4_europe.size())

# Display the roads data.
Map.addLayer(ee.FeatureCollection(grip4_africa).style(**{
    'color': '413B3A',
    'width': 1
}), {}, 'Grip4 Africa')
Map.addLayer(ee.FeatureCollection(grip4_north_america).style(**{
    'color': '413B3A',
    'width': 1
}), {}, 'Grip4 North America')
Map.addLayer(ee.FeatureCollection(grip4_europe).style(**{
    'color': '413B3A',
    'width': 1
}), {}, 'Grip4 Europe')

# Import simplified countries.
countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017')

# Add a function to calculate the feature's geometry area.
# Add the function as a property.
def addArea(feature):
    return feature.set({
        'areaKm': feature.geometry().area().divide(1000 *
            1000)
    }); # km2 squared


# Map the area getting function over the FeatureCollection.
countriesArea = countries.map(addArea)

# Filter to the largest country in Africa.
Algeria = countriesArea.filter(ee.Filter.inList('country_na', [
    'Algeria'
]))

# Display the selected countries.
Map.addLayer(Algeria.style(**{
    'fillColor': 'b5ffb4',
    'color': '00909F',
    'width': 1.0
}), {}, 'Algeria')

# This function calculates the road length per country for the associated GRIP dataset.
def roadLength4Country(country, grip4):

    # Join roads to countries.
    intersectsFilter = ee.Filter.intersects({
        'leftField': '.geo',
        'rightField': '.geo',
        'maxError': 10
    })

    grip4Selected = grip4.filterBounds(country)

    countriesWithRds = ee.Join.saveAll('roads').apply({
        'primary': country,
        'secondary': grip4Selected,
        'condition': intersectsFilter
    }).filter(ee.Filter.neq('roads', None))

    # Return country with calculation of roadLength and roadsPerArea.

def func_gfe(country):
        roadsList = ee.List(country.get('roads'))
        roadLengths = roadsList.map(function(road) {
            return ee.Feature(road).intersection(
                country, 10).length(10)
        })
        roadLength = ee.Number(roadLengths.reduce(ee \
            .Reducer.sum()))
        return country.set({
            'roadLength': roadLength.divide(
                1000), # Convert to km.
            'roadsPerArea': roadLength.divide(ee \
                .Number(country.get('areaKm'))
            )
        })

    return countriesWithRds.map(func_gfe
).select(['country_na', 'areaKm', 'roadLength',














).select(['country_na', 'areaKm', 'roadLength',
        'roadsPerArea'
    ])


# Apply the road length function to Algeria.
roadLengthAlgeria = roadLength4Country(Algeria, grip4_africa)

# Print the road statistics for Algeria.
print('Roads statistics in Algeria', roadLengthAlgeria)

#  -----------------------------------------------------------------------
#  CHECKPOINT
#  -----------------------------------------------------------------------

# Export feature collection to drive.
Export.table.toDrive({
    'collection': roadLengthAlgeria,
    'description': 'RoadStatisticsforAlgeria',
    'selectors': ['country_na', 'roadLength', 'roadsPerArea']
})

# Print the first feature of the grip4 Africa feature collection.
print(grip4_africa.limit(1))

Map.setCenter(-0.759, 9.235, 6)
Map.addLayer(grip4_africa.limit(1),
    {},
    'Road length comparison')

# This function adds line length in km.
def addLength(feature):
    return feature.set({
        'lengthKm': feature.length().divide(1000)
    })


# Calculate the line lengths for all roads in Africa.
grip4_africaLength = grip4_africa.map(addLength)

# Compare with other values.
print('Calculated road length property', grip4_africaLength.limit(1))

# Repeat the analysis to calculate the length of all roads.
# Filter the table geographically: only keep roads in Algeria.
grip4_Algeria = grip4_africaLength.filterBounds(Algeria)

# Visualize the output.
Map.addLayer(grip4_Algeria.style(**{
    'color': 'green',
    'width': 2.0
}), {}, 'Algeria roads')

# Sum the lengths for roads in Algeria.
sumLengthKmAlgeria = ee.Number(
    # Reduce to get the sum.
    grip4_Algeria.reduceColumns(ee.Reducer.sum(), ['lengthKm']) \
    .get('sum')
)

# Print the result.
print('Length of all roads in Algeria', sumLengthKmAlgeria)

#  -----------------------------------------------------------------------
#  CHECKPOINT
#  -----------------------------------------------------------------------

# Add Earth Engine dataset image = ee.Image("USGS/SRTMGL1_003") # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # Chapter: A1.3 Built Environments # Checkpoint: A13b # Author: Erin Trochim # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # Import roads data. grip4_africa = ee.FeatureCollection( 'projects/sat-io/open-datasets/GRIP4/Africa'), grip4_north_america = ee.FeatureCollection( 'projects/sat-io/open-datasets/GRIP4/North-America'), grip4_europe = ee.FeatureCollection( 'projects/sat-io/open-datasets/GRIP4/Europe') # Check the roads data sizes. print('Grip4 Africa size', grip4_africa.size()) print('Grip4 North America size', grip4_north_america.size()) print('Grip4 Europe size', grip4_europe.size()) # Display the roads data. Map.addLayer(ee.FeatureCollection(grip4_africa).style(**{ 'color': '413B3A', 'width': 1 }), {}, 'Grip4 Africa') Map.addLayer(ee.FeatureCollection(grip4_north_america).style(**{ 'color': '413B3A', 'width': 1 }), {}, 'Grip4 North America') Map.addLayer(ee.FeatureCollection(grip4_europe).style(**{ 'color': '413B3A', 'width': 1 }), {}, 'Grip4 Europe') # Import simplified countries. countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017') # Add a function to calculate the feature's geometry area. # Add the function as a property. def addArea(feature): return feature.set({ 'areaKm': feature.geometry().area().divide(1000 * 1000) }); # km2 squared # Map the area getting function over the FeatureCollection. countriesArea = countries.map(addArea) # Filter to the largest country in Africa. Algeria = countriesArea.filter(ee.Filter.inList('country_na', [ 'Algeria' ])) # Display the selected countries. Map.addLayer(Algeria.style(**{ 'fillColor': 'b5ffb4', 'color': '00909F', 'width': 1.0 }), {}, 'Algeria') # This function calculates the road length per country for the associated GRIP dataset. def roadLength4Country(country, grip4): # Join roads to countries. intersectsFilter = ee.Filter.intersects({ 'leftField': '.geo', 'rightField': '.geo', 'maxError': 10 }) grip4Selected = grip4.filterBounds(country) countriesWithRds = ee.Join.saveAll('roads').apply({ 'primary': country, 'secondary': grip4Selected, 'condition': intersectsFilter }).filter(ee.Filter.neq('roads', None)) # Return country with calculation of roadLength and roadsPerArea. def func_gfe(country): roadsList = ee.List(country.get('roads')) roadLengths = roadsList.map(function(road) { return ee.Feature(road).intersection( country, 10).length(10) }) roadLength = ee.Number(roadLengths.reduce(ee \ .Reducer.sum())) return country.set({ 'roadLength': roadLength.divide( 1000), # Convert to km. 'roadsPerArea': roadLength.divide(ee \ .Number(country.get('areaKm')) ) }) return countriesWithRds.map(func_gfe ).select(['country_na', 'areaKm', 'roadLength', ).select(['country_na', 'areaKm', 'roadLength', 'roadsPerArea' ]) # Apply the road length function to Algeria. roadLengthAlgeria = roadLength4Country(Algeria, grip4_africa) # Print the road statistics for Algeria. print('Roads statistics in Algeria', roadLengthAlgeria) # ----------------------------------------------------------------------- # CHECKPOINT # ----------------------------------------------------------------------- # Export feature collection to drive. Export.table.toDrive({ 'collection': roadLengthAlgeria, 'description': 'RoadStatisticsforAlgeria', 'selectors': ['country_na', 'roadLength', 'roadsPerArea'] }) # Print the first feature of the grip4 Africa feature collection. print(grip4_africa.limit(1)) Map.setCenter(-0.759, 9.235, 6) Map.addLayer(grip4_africa.limit(1), {}, 'Road length comparison') # This function adds line length in km. def addLength(feature): return feature.set({ 'lengthKm': feature.length().divide(1000) }) # Calculate the line lengths for all roads in Africa. grip4_africaLength = grip4_africa.map(addLength) # Compare with other values. print('Calculated road length property', grip4_africaLength.limit(1)) # Repeat the analysis to calculate the length of all roads. # Filter the table geographically: only keep roads in Algeria. grip4_Algeria = grip4_africaLength.filterBounds(Algeria) # Visualize the output. Map.addLayer(grip4_Algeria.style(**{ 'color': 'green', 'width': 2.0 }), {}, 'Algeria roads') # Sum the lengths for roads in Algeria. sumLengthKmAlgeria = ee.Number( # Reduce to get the sum. grip4_Algeria.reduceColumns(ee.Reducer.sum(), ['lengthKm']) \ .get('sum') ) # Print the result. print('Length of all roads in Algeria', sumLengthKmAlgeria) # ----------------------------------------------------------------------- # CHECKPOINT # -----------------------------------------------------------------------

Display the interactive map¶

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Map

Map