Projected Cartopy Map

import pandas as pd
from vizent import vizent_plot
import matplotlib.text as text
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import warnings
warnings.filterwarnings('ignore')

df = pd.read_csv('sample-data/temperatures.csv')

# Use cartopy projection to web mercator
crs = ccrs.epsg(3857)
projected_points = crs.transform_points(x=df['longitude'],
                                        y=df['latitude'],
                                        src_crs=4326)
x = projected_points[:, 0]
y = projected_points[:, 1]

fig = vizent_plot(x,
                  y,
                  df['temperature_2m_max'],
                  df['diff'],
                  [21] * df.shape[0],
                  use_cartopy=True,
                  cartopy_projection=crs,
                  extent=[-15, 30, 30, 60],
                  shape_max=10,
                  shape_min=-10,
                  shape_n=4,
                  interval_type='limit',
                  color_min=10,
                  color_max=50,
                  colormap='YlOrRd',
                  color_label='Temperature\n(daily max, $^\circ C$)',
                  shape_label='Difference from\n20-year mean\non this date ($^\circ C$)',
                  glyph_legend_title='Map Legend',
                  label_fontsize=7)

# Add inequalities to shape legend to emphasise limit/threshold approach to intervals.
for child in fig.axes[0].get_children():
    if type(child)==text.Annotation:
        if child.get_text()[0] == '-':
            child.set_text('$<$' + child.get_text())
        else:
            try:
                value = int(child.get_text()[0])
                if value != 0:
                    child.set_text('$\geq$' + child.get_text())
            except:
                pass

fig.suptitle('Maximum daily temperatures in cities with at least 1M residents on 15th July 2023', y=0.92)

plt.text(x=0.145,
        y=0.07,
        s="Weather data from open-meteo.com (10.5281/zenodo.8112599) - City data from geonames.org - Visualisation by CUSP London",
        transform=fig.transFigure,
        fontsize=8)

fig.set_size_inches(10, 6.5)