Is there a way to get the mean annual maximum of monthly data with an xarray function?

[pecos27]

Is it possible in xarray to get the mean annual maximum of monthly data?
I am hoping to get the maximum temperature per year, so for each year there would be one maximum and then can take the annual mean to get the mean annual maximum.

I tried get the maxima per year via a loop, but I was wondering if there is another way do it just through xarray?

Example code below:

ds = xr.tutorial.open_dataset('rasm')

# getting 1980 - 1982 
Tair = ds.Tair[4:-8]

#Tair_max = Tair.max(dim='time')


# attempt using a loop

maximum_every_12_months = np.zeros((int(Tair.shape[0]/12),Tair.shape[1],Tair.shape[2]))

for i in range(12):
    print(i)
    maximum_every_12_months[i,:,:] = np.max(Tair[i::12,:,:],axis=0)

[TomNicholas]

Have you seen the GroupBy functionality? If you added a year coordinate to your data then you could do something like da.groupby("year").max().

[spencerkclark]

Indeed groupby is the way to go. Further, as long as the time coordinate is composed of some form of datetime object, you can do something like this:

da.groupby("time.year").max()

In other words, there is no need to explicitly create your own "year" coordinate.

[pecos27]

Thank you! yes this works perfectly. much nicer than using a loop :)