Fix Matplotlib Index Error
Fix Matplotlib Index Error

This fixes the error: 
IndexError: only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are vs
clementval/serialbox,clementval/serialbox,MeteoSwiss-APN/serialbox,MeteoSwiss-APN/serialbox,clementval/serialbox,MeteoSwiss-APN/serialbox,clementval/serialbox,MeteoSwiss-APN/serialbox