等值线图未显示

Question

I am a fresh starter with Python for Data science and this is my first help request here (then apologize in advance for some mistakes). Need your support to get why this (simple data frame based) choropleth map is not showing. Read quite several discussion on the argument then I verified all the main stuff: district names and NAAM (in the geojson) both in str etc - but still I am stuck and I can't see the map (only the legend). Lemme know if more info are needed, below u can find the code: In [9]:

df_clo=dfrc.groupby(['District']).mean()
df_clo.reset_index(inplace=True)
df_clo=df_clo[['District','Rent']]
df_clo['District'] = df_clo['District'].str.upper()
df_clo

Out[9]:

District    Rent
0   BINNENSTAD  1792.281250
1   NOORDOOST   1763.558824
2   OOST    1739.186047
3   ZUID    1562.142857
4   ZUIDWEST    1397.689655

In [10]:

latitude = 52.09083
longitude = 5.12222
print('The geograpical coordinate of Utrecht are {}, {}.'.format(latitude, longitude))# create map of Utrecht using latitude and longitude values
utrecht_geo = r'https://raw.githubusercontent.com/umbesallfi/Coursera_Capstone/master/wijk_.geojson'
# create a numpy array of length 6 and has linear spacing from the minium total immigration to the maximum total immigration
threshold_scale = np.linspace(df_clo['Rent'].min(),
                              df_clo['Rent'].max(),
                              6, dtype=int)
threshold_scale = threshold_scale.tolist() # change the numpy array to a list
threshold_scale[-1] = threshold_scale[-1] + 1 # make sure that the last value of the list is greater than the maximum immigration
# let Folium determine the scale.
map_utr = folium.Map(location=[latitude, longitude], zoom_start=2, tiles='Mapbox Bright')
map_utr.choropleth(
    geo_data=utrecht_geo,
    data=df_clo,
    columns=['District', 'Rent'],
    key_on='feature.properties.NAAM',
    threshold_scale=threshold_scale,
    fill_color='YlOrRd', 
    fill_opacity=0.7, 
    line_opacity=0.2,
    legend_name='Price in Utrecht by Wijk',
    reset=True
)
map_utr

Answer 1

District names are not stored in block letters in your wijk_.geojson file. Therefore, it should be enough to remove this line:

df_clo['District'] = df_clo['District'].str.upper()

My code:

import folium
import pandas as pd
import numpy as np

m = folium.Map(location=[52.09083, 5.12222],
               zoom_start=12,
               control_scale=True)

df_clo = pd.DataFrame({'District':['Binnenstad','Noordoost','Oost','Zuid','Zuidwest'],
                       'Rent':[1792.281250,
                               1763.558824,
                               1739.186047,
                               1562.142857,
                               1397.689655]})

threshold_scale = np.linspace(df_clo['Rent'].min(),
                              df_clo['Rent'].max(),
                              6, dtype=int)
threshold_scale = threshold_scale.tolist() # change the numpy array to a list
threshold_scale[-1] = threshold_scale[-1] + 1 # make sure that the last value of the list is greater than the maximum immigration

utrecht_geo = 'wijk_.geojson'

folium.Choropleth(geo_data=utrecht_geo,
                  name='choropleth',
                  data=df_clo,
                  columns=['District', 'Rent'],
                  key_on='feature.properties.NAAM',
                  threshold_scale=threshold_scale,
                  fill_color='YlOrRd',
                  fill_opacity=0.7,
                  line_opacity=0.2,
                  legend_name='Price in Utrecht by Wijk',).add_to(m)

folium.LayerControl().add_to(m)

m

returns this map: