NCL Website header
NCL Home > Documentation > Functions > General applied math, Statistics


Calculates standardized anomalies of the rightmost dimension at all other dimensions and retains metadata.


load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"

	function dim_standardize_Wrap (
		x    : numeric,  
		opt  : integer   

	return_val [dimsizes(x)] :  float or double



A variable of numeric type and any dimensionality.


Setting opt=1 means to use the population standard deviation (i.e., divide by the number of non-missing values [N]). Otherwise, the sample standard deviation is used for normalization (i.e., divide by [N-1]).

Return value

The output is of type double if the input is double, and float otherwise.

The dimensionality is the same as the input dimensionality.


The dim_standardize function calculates and removes the mean from all elements of the n-1th (rightmost) dimension and retains metadata. It then standardizes the rightmost dimension by dividing the resulting deviations from the mean by the standard deviation of the rightmost dimension. These values are often called standardized anomalies. This is repeated for each index of the dimensions 0...n-2. A wrapper function. Missing values are ignored.

Use dim_standardize_n_Wrap if you want to specify which dimensions to do the calculation on.

See Also

dim_standardize_n_Wrap, dim_standardize_n, dim_median, dim_stddev, dim_num, dim_product, dim_rmsd, dim_rmvmean, dim_rmvmed, dim_standardize, dim_stat4, dim_stddev, dim_sum, dim_variance


Example 1: Let x be a 1-dimensional array: (a) Create a new variable, xNew, that contains standardized values; (b) replace the variable x with the standardized values. Use the population standard deviation.

  xNew = dim_standardize_Wrap(x, 1)    ; new variable with meta data
  x    = dim_standardize_Wrap(x, 1)    ; overwrite with standardized anomalies
  x@long_name = x@long_name +": standardized anomalies"
Example 2: Let x be a 3-dimensional array with dimension sizes (ntim, nlat, nlon). Standardize values of the rightmost (here, "nlon") dimension. Use the sample standard deviation (opt=0).
   xLon = dim_standardize_Wrap( x,0 )    ; with metadata
   x    = dim_standardize (x,0)    ; overwrite with deviations
Example 3: Let x be a 3-dimensional array with named dimensions (time, lat, lon) and dimension sizes (ntim, nlat, nlon). Standardize the values of the time dimension at all lat/lon indices, 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_standardize_n_Wrap to avoid having to reorder your data.

   xTime = dim_standardize(x(lat|:, lon|:, time|:), 0)  ; no metadata
   xTime = dim_standardize_Wrap(x(lat|:, lon|:, time|:), 0)  ; has metadata
   xTime = dim_standardize_n_Wrap(x, 0, 0)  ; w/metadata, no reordering needed
Example 4: Let x be as in Example 3 and let x contain monthly means for (say) 10 years of data (ntim=120). Standardized monthly anomalies for each month could be calculated using array subscripting and Named Subscripting to reorder the input array such that "time" is the rightmost dimension. (opt=0 or 1)
   xJan  = dim_standardize_Wrap(x(lat|:, lon|:, time|0:ntim-1:12), opt)
   xJuly = dim_standardize_Wrap(x(lat|:, lon|:, time|6:ntim-1:12), opt)