Right here’s the complete code (written in JupyterLab). I’ll break down the code blocks within the following sections.
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import geopandas as gpd
from geopy.distance import great_circle# SEC faculties with coordinates (coords by ChatGPT4):
information = {
'faculty': ['Alabama', 'LSU', 'Ole Miss', 'Miss State',
'Auburn', 'Arkansas', 'Missouri', 'Vanderbilt',
'Tennessee', 'Florida', 'Georgia', 'Kentucky',
'S. Carolina', 'TAMU', 'Texas', 'Oklahoma'],
'latitude': [33.209, 30.412, 34.365, 33.456,
32.603, 36.068, 38.951, 36.162,
35.960, 29.651, 33.950, 38.049,
34.000, 30.620, 30.284, 35.222],
'longitude': [-87.538, -91.177, -89.526, -88.811,
-85.484, -94.172, -92.328, -86.784,
-83.920, -82.324, -83.377, -84.500,
-81.034, -96.340, -97.740, -97.445]
}
df = pd.DataFrame(information)
# Choose a college to plot the space from.
# Use the identical title as within the earlier information dict:
SCHOOL = 'Texas'
# Set the grid decision.
# Bigger = increased res and smoother contours:
RESOLUTION = 500
# Get coordinates for SCHOOL:
school_index = df[df['school'] == SCHOOL].index[0]
school_coords = df.loc[school_index, ['latitude', 'longitude']].to_numpy()
# Create grid of factors for interpolation:
x_min, x_max = df['longitude'].min(), df['longitude'].max()
y_min, y_max = df['latitude'].min(), df['latitude'].max()
xx, yy = np.meshgrid(np.linspace(x_min, x_max, RESOLUTION),
np.linspace(y_min, y_max, RESOLUTION))
# Calculate distances from SCHOOL to each level in grid:
distances = np.zeros(xx.form)
for i in vary(xx.form[0]):
for j in vary(xx.form[1]):
point_coords = (yy[i, j], xx[i, j])
distances[i, j] = great_circle(school_coords, point_coords).miles
# Create the color-filled contour map:
fig, ax = plt.subplots(1, 1, figsize=(10, 8))
contour = ax.contourf(xx, yy, distances,
cmap='coolwarm',
alpha=0.9)
cbar = fig.colorbar(contour, ax=ax, shrink=0.7)
cbar.set_label(f'Distance from {SCHOOL} (miles)')
ax.scatter(df['longitude'], df['latitude'], s=2, shade='black')
# Load state boundaries from US Census Bureau:
url = 'https://www2.census.gov/geo/tiger/GENZ2021/shp/cb_2021_us_state_20m.zip'
states = gpd.read_file(url)
# Filter states inside the map limits:
states = states.cx[x_min:x_max, y_min:y_max]
# Plot the state boundaries:
states.boundary.plot(ax=ax, linewidth=1, edgecolor='black')
# Add labels for the colleges:
for i, faculty in enumerate(df['school']):
ax.annotate(
faculty,
(df['longitude'][i], df['latitude'][i]),
textcoords="offset factors",
xytext=(2, 1),
ha='left',
fontsize=8
)
ax.set_xlabel('Longitude')
ax.set_ylabel('Latitude')
ax.set_title(f'Distance from {SCHOOL} to Different SEC Faculties')
# fig.savefig('distance_map.png', dpi=600)
plt.present()
And right here’s the output, exhibiting the space from the College of Texas in Austin to the opposite SEC faculties:
Importing Libraries
This mission requires NumPy, Matplotlib, pandas, geopandas, geopy, and scipy. You will discover set up directions within the hyperlinks.
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import geopandas as gpd
from geopy.distance import great_circle
Loading Information
For the enter information, I made a listing of the colleges after which had ChatGPT produce the dictionary with the lat-lon coordinates. The dictionary was then transformed right into a pandas DataFrame named df.
# SEC faculties with coordinates (coords by ChatGPT4):
information = {
'faculty': ['Alabama', 'LSU', 'Ole Miss', 'Miss State',
'Auburn', 'Arkansas', 'Missouri', 'Vanderbilt',
'Tennessee', 'Florida', 'Georgia', 'Kentucky',
'S. Carolina', 'TAMU', 'Texas', 'Oklahoma'],
'latitude': [33.209, 30.412, 34.365, 33.456,
32.603, 36.068, 38.951, 36.162,
35.960, 29.651, 33.950, 38.049,
34.000, 30.620, 30.284, 35.222],
'longitude': [-87.538, -91.177, -89.526, -88.811,
-85.484, -94.172, -92.328, -86.784,
-83.920, -82.324, -83.377, -84.500,
-81.034, -96.340, -97.740, -97.445]
}df = pd.DataFrame(information)
Assigning Constants
The code will produce a distance map from one of many listed SEC faculties. We’ll assign the varsity’s title (typed precisely because it seems within the dictionary) to a continuing named SCHOOL.
# Choose a college to plot the space from.
# Use the identical title as within the information dict:
SCHOOL = 'Texas'
To manage the “smoothness” of the contours, we’ll use a continuing named RESOLUTION. The bigger the quantity, the finer the underlying grid and thus the smoother the contours. Values round 500–1,000 produce good outcomes.
# Set the grid decision.
# Bigger = increased res and smoother contours:
RESOLUTION = 500
Getting the Faculty Location
Now to get the desired faculty’s map coordinates. On this case, the varsity would be the College of Texas in Austin, Texas.
# Get coordinates for SCHOOL:
school_index = df[df['school'] == SCHOOL].index[0]
school_coords = df.loc[school_index, ['latitude', 'longitude']].to_numpy()
The primary line identifies the DataFrame index of the varsity specified by the SCHOOL fixed. This index is then used to get the varsity’s coordinates. As a result of index returns a listing of indices the place the situation is true, we use [0] to get the primary (presumably solely) merchandise on this record.
Subsequent, we extract latitude and longitude values from the DataFrame and convert them right into a NumPy array with the to_numpy() technique.
Should you’re unfamiliar with NumPy arrays, take a look at this text:
Creating the Grid
Earlier than we make a contour map, we should construct an everyday grid and populate the grid nodes (intersections) with distance values. The next code creates the grid.
# Create grid of factors for interpolation:
x_min, x_max = df['longitude'].min(), df['longitude'].max()
y_min, y_max = df['latitude'].min(), df['latitude'].max()
xx, yy = np.meshgrid(np.linspace(x_min, x_max, RESOLUTION),
np.linspace(y_min, y_max, RESOLUTION))
Step one right here is to get the min and max values (x_min, x_max and y_min, y_max) of the longitude and latitude from the DataFrame.
Subsequent, we use NumPy’s meshgrid() technique to create a grid of factors inside the bounds outlined by the min and max latitudes and longitudes.
Right here’s how the grid appears to be like for a decision of 100:
Every node will maintain a worth that may be contoured.
Calculating Distances
The next code calculates concentric distances from the desired faculty.
# Calculate distances from SCHOOL to each level in grid:
distances = np.zeros(xx.form)
for i in vary(xx.form[0]):
for j in vary(xx.form[1]):
point_coords = (yy[i, j], xx[i, j])
distances[i, j] = great_circle(school_coords, point_coords).miles
The primary order of enterprise is to initialize a NumPy array known as distances. It has the identical form because thexx grid and is stuffed with zeroes. We’ll use it to retailer the calculated distances from SCHOOL.
Subsequent, we loop over the rows of the grid, then, in a nested loop, iterate over the columns of the grid. With every iteration we retrieve the coordinates of the purpose at place (i, j) within the grid, with yy and xx holding the grid coordinates.
The ultimate line calculates the great-circle distance (the space between two factors on a sphere) from the varsity to the present level coordinates (point_coords). The last word result’s an array of distances with items in miles.
Creating the Map
Now that we’ve got x, y, and distance information, we will contour the space values and make a show.
# Create the color-filled contour map:
fig, ax = plt.subplots(1, 1, figsize=(10, 8))
contour = ax.contourf(xx, yy, distances,
cmap='coolwarm',
alpha=0.9)
cbar = fig.colorbar(contour, ax=ax, shrink=0.7)
cbar.set_label(f'Distance from {SCHOOL} (miles)')
ax.scatter(df['longitude'], df['latitude'], s=2, shade='black')
We begin by establishing a Matplotlib determine of measurement 10 x 8. Should you’re not accustomed to the fig, ax terminology, take a look at this terrific article for a fast introduction:
To attract the color-filled contours we use Matplotlib’s contourf() technique. It makes use of the xx, yy, and distancesvalues, the coolwarm colormap, and a slight quantity of transparency (alpha=0.9).
The default shade bar for the show is missing, for my part, so we customise it considerably. The fig.colorbar() technique provides a shade bar to the plot to point the space scale. The shrink argument retains the peak of the colour bar from being disproportionate to the plot.
Lastly, we use Matplotlib’s scatter() technique so as to add the varsity places to the map, with a marker measurement of 2. Later, we’ll label these factors with the varsity names.
Including the State Boundaries
The map presently has solely the varsity places to make use of as landmarks. To make the map extra relatable, the next code provides state boundaries.
# Load state boundaries from US Census Bureau:
url = 'https://www2.census.gov/geo/tiger/GENZ2021/shp/cb_2021_us_state_20m.zip'
states = gpd.read_file(url)# Filter states inside the map limits:
states = states.cx[x_min:x_max, y_min:y_max]
# Plot the state boundaries:
states.boundary.plot(ax=ax, linewidth=1, edgecolor='black')
The third line makes use of geopandas’ cx indexer technique for spatial slicing. It filters geometries in a GeoDataFrame primarily based on a bounding field outlined by the minimal and most x (longitude) and y (latitude) coordinates. Right here, we filter out all of the states exterior the bounding field.
Including Labels and a Title
The next code finishes the plot by tying up a couple of unfastened ends, resembling including the varsity names to their map markers, labeling the x and y axes, and setting an updateable title.
# Add labels for the colleges:
for i, faculty in enumerate(df['school']):
ax.annotate(
faculty,
(df['longitude'][i], df['latitude'][i]),
textcoords="offset factors",
xytext=(2, 1),
ha='left',
fontsize=8
)ax.set_xlabel('Longitude')
ax.set_ylabel('Latitude')
ax.set_title(f'Distance from {SCHOOL} to Different SEC Faculties')
fig.savefig('distance_map.png', dpi=600)
plt.present()
To label the colleges, we use a for loop and enumeration to decide on the proper coordinates and names for every faculty and use Matplotlib’s annotate() technique to submit them on the map. We use annotate() somewhat than the textual content() technique to entry the xytext argument, which lets us shift the label to the place we wish it.