从CSV文件中读取经纬度时未显示Folium贴图

Question

我第一次在Jupyter笔记本中调用地图时，地图会按预期显示，但是当我在最后一行中运行地图时，会显示一个较大的空白而不是地图。非常感谢您的帮助。

'''

import pandas as pd
import folium as fl

# read csv file into dataframe
df = pd.read_csv('./dsc-v2-mod1-final-project-dc-ds-career- \
                  042219/kc_house_data.csv')

map = fl.Map(location=[df['lat'].mean(), df['long'].mean()])
map  # map displays as expected

# return different colors for folium markercolor based on house sale 
# price
def marker_color(price):
    if (price >= 77000.00) and (price <= 199999.00):
        colr = 'yellow'
    elif (price >= 200000.00) and (price <= 399999.00):
        colr = 'green'
    elif (price >= 400000.00) and (price <= 599999.00):
        colr = 'blue'
    elif (price >= 600000.00 ) and (price <= 799999.00):
        colr = 'orange'
    else:
        colr = 'red'


# iterate over dataframe and get lat, long, and price and assign 
# them to folium Marker as arguments
for index, row in df.iterrows():
    fl.Marker([row['lat'],row['long']], \
    icon=fl.Icon(color=marker_color(row['price']), \
    icon_color='green')).add_to(map)

map # blank space is displayed instead of the map

'''