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getbitsone

Unpacks one-bit chunks from the input array.

Prototype

	function getbitsone (
		npack  : numeric   ; byte, ubyte, short, ushort, integer
	)

	return_val  :  typeof(npack)

Arguments

npack

A byte, ubyte, short, ushort, or integer array of any dimensionality. (The recognition of ubyte and ushort types was added in NCL V6.0.0)

Description

getbitsone unpacks one-bit chunks from the input array npack into the return array. The leftmost dimensions of the return array will be the same as the dimensions of npack, and there will be an additional rightmost dimension added, where if npack is of type (u)byte/(u)short/integer, the size of the added dimension will be 8/16/32.

Examples

Example 1

Assume x is a 2D array with dimensions nlat x mlon and of type byte. The following code snippet:

   xchunk = getbitsone (x)

will return an array dimensioned nlat x mlon x 8. Users can now, for example, check to if bit 4 at some arbitrary latitude/longitude is "on" or "off".

Example 2

Assume cloud_mask is a 3D array of type byte and dimensioned nB(=6) x yCell(=2030) x xCell(=1354). The 8 bits associated with the first byte (i.e. (0,:,:)) can be unpacked via the following:

   cmBit  = getbitsone ( cloud_mask(0,:,:) )

  printVarSummary (cmBit)

The print command yields:

Variable: cmBit
Type: byte
Total Size: 21988960 bytes
            21988960 values
Number of Dimensions: 3
Dimensions and sizes:   [2030] x [1354] x [8]
    .
    .
    .

Use print to list the bit values at a particular location. For example, assume yCell=1000 and xCell=500:

   print( cmBit(1000,500,:))