When working with Python’s cartopy library, it is common to encounter issues with borders and coastlines interfering with the desired output. This can be frustrating, but fortunately, there are several ways to solve this problem.

Option 1: Adjusting the linewidth

One way to address the issue of borders and coastlines interfering is by adjusting the linewidth. By increasing the linewidth, the borders and coastlines will become more prominent and less likely to interfere with other elements in the plot.

import cartopy.crs as ccrs
import matplotlib.pyplot as plt

# Create a figure and axis
fig, ax = plt.subplots(figsize=(10, 10), subplot_kw={'projection': ccrs.PlateCarree()})

# Increase the linewidth
ax.coastlines(linewidth=2)

# Add other elements to the plot
# ...

# Show the plot
plt.show()

Option 2: Removing borders and coastlines

If adjusting the linewidth does not provide the desired result, another option is to completely remove the borders and coastlines from the plot. This can be achieved by setting the linewidth to 0 or using the `ax.background_patch.set_visible(False)` method.

import cartopy.crs as ccrs
import matplotlib.pyplot as plt

# Create a figure and axis
fig, ax = plt.subplots(figsize=(10, 10), subplot_kw={'projection': ccrs.PlateCarree()})

# Remove borders and coastlines
ax.coastlines(linewidth=0)
# or
ax.background_patch.set_visible(False)

# Add other elements to the plot
# ...

# Show the plot
plt.show()

Option 3: Adjusting the zorder

Another approach to solve the issue is by adjusting the zorder of the borders and coastlines. The zorder determines the order in which elements are drawn on the plot. By setting a higher zorder for the borders and coastlines, they will be drawn on top of other elements, reducing interference.

import cartopy.crs as ccrs
import matplotlib.pyplot as plt

# Create a figure and axis
fig, ax = plt.subplots(figsize=(10, 10), subplot_kw={'projection': ccrs.PlateCarree()})

# Adjust the zorder
ax.coastlines(zorder=10)

# Add other elements to the plot
# ...

# Show the plot
plt.show()

After considering these three options, it is difficult to determine which one is the best as it depends on the specific requirements of the plot and personal preference. However, adjusting the linewidth or removing the borders and coastlines altogether are often the most effective solutions. Experimenting with different approaches and fine-tuning the parameters will help achieve the desired output.