faceted plot uses wrong vmin and vmax

[WalidGharianiEAGLE]

I was curious to extract the vmin and vmax used with faceted plot, and i found out that it doesn't use the right values.

import xarray as xr
import numpy as np

airtemps = xr.tutorial.open_dataset("air_temperature")
air = airtemps.air - 273.15

t = air.isel(time=slice(0, 365 * 4, 250))
t.coords

t.plot(x="lon", y="lat", col="time", col_wrap=3)

## lets check the min and max of the air DataArray
min_air, max_air = np.nanmin(t.values) , np.nanmax(t.values) 
print(min_air, max_air)
## >> -46.550003 36.950012

## the max is max_air = 36.950012 while in the facet plot, the vmax is more than 40. why is that ?

[keewis]

the max is max_air = 36.950012 while in the facet plot, the vmax is more than 40. why is that ?

That's because the function detects a diverging dataset and thus centers around 0:

vmax = max(abs(min), abs(max))
vmin = -vmax

if that's not what you want, you can disable this using center=False:

t.plot(x="lon", y="lat", col="time", col_wrap=3, center=False)

[WalidGharianiEAGLE]

I see! In my opinion, by default it should be center=False