GDK Error if executing headless or running via SSH

[kevdel]

The following terminal error will appear if the monthplot.py script is ran on a headless device (e.g accessing a pi over ssh with no X Server running)

Unable to init server: Could not connect: Connection refused Unable to init server: Could not connect: Connection refused (monthplot.py:316): Gdk-CRITICAL **: 14:22:56.567: gdk_cursor_new_for_display: assertion 'GDK_IS_DISPLAY (display)' failed (monthplot.py:316): Gdk-CRITICAL **: 14:22:56.572: gdk_cursor_new_for_display: assertion 'GDK_IS_DISPLAY (display)' failed

A working fix to remove this is to add some logic on the import statements

import os, io, subprocess
import pandas as pd
import csv, time

if os.environ.get('DISPLAY') is None: # this variable will not be set when X Server is not running
 import matplotlib as  mplib
 # set a  different display back-end to squash the error
 mplib.use('Agg')

import matplotlib.pyplot as plt
import seaborn as sns

the rest of the file is unmodified

[caiusseverus]

I've not seen that issue on my pi, which is running headless, but I'm happy to add your change in if it fixes the issue where it does arise. Thanks.