pi-weather | Playground to use a raspberry pi for weather-stuff

I run domoticz on a PI3b with Raspbian, for better effiency the PI3b has now a 7" screen to show domotics behaviour + weather-station information + internet forecast... To show all of this I've coded a C++/WXWidget app with graphics for temp/pressure... Temp/pressures graphs are with Python3/matplotlib plotted, saved as 3 png files. The Python script read datas in files and plot/save the graphs.

It works good from terminal.... but no way to work with crontab, or with an "os.execute()" from events lua-scripts of domoticz...

I've pushed Up all permissions/access for scripts and png files (read/write)

One python script read data from bme280 sensor, crontab 2 minutes, no problem, it works from terminal, crontab, lua events...

Second script read datas, plot graphs and send http json command in order to update a device in domoticz. This works fine from terminal, but not from domoticz (lua os.execute()) or from crontab.

call in crontab: sudo /usr/bin/python3 /home/pi/Desktop/graph.py

call from domoticz lua script: os.execute('sudo /usr/bin/python3 /home/pi/Desktop/graph.py')

from terminal it works fine with python, /usr/bin/python, or /usr/bin/python3 (--> matplotlib)

python --version = 3.7.0

It looks like a problem beetween many python versions, the good one is not called from crontab and lua-scripts.... How to fix-it ?

default python version to 2.7.0, 3.0, 3.6, 3.7 tested to check problem with env/bin/path... only problem found with urllib.urlopen changed with "urlopen from urllib.request"