Computes the average of a variable's rightmost dimension at all other dimensions.
function dim_avg ( x : numeric ) return_val : float or double
A variable of numeric type and any dimensionality.
The output will be double if x is double, and float otherwise.
The output dimensionality is the same as the first n-2 dimensions of the input variable. That is, the dimension rank of the input variable will be reduced by one.
The dim_avg function computes the average of all elements of the n-1th (rightmost) dimension for each index of the dimensions 0...n-2. Missing values are ignored.
Use dim_avg_n if you want to specify which dimension(s) to do the average across.
Use dim_avg_Wrap if retention of metadata is desired.
Create a variable (q) of size (3,5,10) array. Then calculate the average of the rightmost dimension.
q = random_uniform(-20,100,(/3,5,10/)) qAvg = dim_avg(q) ;==> qAvg(3,5)Example 2
Let z be of size (ntim,nlat,mlon) and with named dimensions "time", "lat" and "lon", respectively. Then, for each time and latitude, the zonal mean (ie, average of all non-missing longitudes) is:
zAvgLon = dim_avg( z ) ; ==> zAvgLon(ntim,nlat)Generally, users prefer that the returned variable have metadata associated with it. This can be accomplished via the dim_avg_Wrap function:
zAvgLon = dim_avg_Wrap( x ) ; ==> zAvgLon(time,lat)Example 3
Let z be defined as in example 2: z(time,lat,lon). Compute the time average at each latitude/longitude grid point. Use NCL's named subscripting to reorder the input array such that "time" is the rightmost dimension.
Note: in V5.1.1, you will be able to use dim_avg_n to avoid having to reorder your data.
zAvgTime = dim_avg( z(lat|:, lon|:, time|:) ) ; ==> zAvgTime(nlat,nlon) zAvgTime = dim_avg_n( z, 0 ) ; no reordering neededIf metadata is desired use:
zAvgTime = dim_avg_Wrap( z(lat|:, lon|:, time|:) ) ; ==> zAvgTime(lat,lon) zAvgTime = dim_avg_n_Wrap( z, 0 ) ; no reordering needed