Trend and anomaly analysis question

[Salil-P-Rice]

Thank you for all of your contributions. Your notebooks were really helpful for climate analysis. I was not able to understand how you came up with reshaping dataset at "421". will it be possible for you to provide more context? Thank you

ncset= netcdf(r'data/sst.mnmean.nc')
lons = ncset['lon'][:]
lats = ncset['lat'][:]
sst = ncset['sst'][1:421,:,:] # 1982-2016 to make it divisible by 12
nctime = ncset['time'][1:421]
t_unit = ncset['time'].units

try :
t_cal =ncset['time'].calendar
except AttributeError : # Attribute doesn't exist
t_cal = u"gregorian" # or standard

nt, nlat, nlon = sst.shape
ngrd = nlon*nlat