Routines (alphabetical) > Routines: N > NCDF Routines > NCDF_VARGET

# NCDF_VARGET

The NCDF_VARGET procedure retrieves a hyperslab of values from a NetCDF variable. The NetCDF file must be in data mode to use this procedure.

## Examples

Suppose that a 230 by 230 image is saved in the NetCDF file `dave.nc`. The following commands extract both the full image and a 70x70 sub-image starting at [80,20] sampling every other X pixel and every third Y pixel:

; A variable that contains the offset for the sub-image:

offset = [80, 20]

; The dimensions of the sub-image:

count = [70, 70]

; Create a variable to be used as a value for the STRIDE keyword.

; Every other X element and every third Y element will be sampled:

stride = [2, 3]

; Open the NetCDF file:

id = NCDF_OPEN('dave.nc')

; Get the variable ID for the image:

image = NCDF_VARID(id, 'image')

; Get the full image:

NCDF_VARGET, id, image, fullimage

; Extract the sub-sampled image:

NCDF_VARGET, id, image, subimage, $

COUNT=count, STRIDE=stride, OFFSET=offset

; Close the NetCDF file:

NCDF_CLOSE, id

## Syntax

NCDF_VARGET, Cdfid, Varid, Value [, COUNT=vector] [, OFFSET=vector] [, STRIDE=vector]

## Arguments

### Cdfid

The NetCDF ID, returned from a previous call to NCDF_OPEN, NCDF_CREATE, or NCDF_GROUPDEF.

### Varid

The NetCDF variable ID, returned from a previous call to NCDF_VARDEF or NCDF_VARID, or the name of the variable.

### Value

A named variable in which the values are returned. NCDF_VARGET sets Value’s size and data type as appropriate.

## Keywords

### COUNT

An optional vector containing the counts to be used in reading Value. COUNT is a 1-based vector with an element for each dimension of the data to be written.The default matches the size of the variable so that all data is written out.

### OFFSET

An optional vector containing the starting position for the read. The default start position is [0, 0, ...].

### STRIDE

An optional vector containing the strides, or sampling intervals, between accessed values of the NetCDF variable. The default stride vector is that for a contiguous read, [1, 1, ...].

## Version History

Pre 4.0 | Introduced

## See Also

NCDF_VARGET1, NCDF_VARID, NCDF_VARINQ, NCDF_VARPUT