gdaUpdateAndPack#

Purpose#

Updates a variable in a GAUSS Data Archive, leaving no empty bytes if the updated variable is smaller or larger than the variable it is replacing.

Format#

retcode = gdaUpdateAndPack(filename, x, varname)#

Parameters:

filename (string) – name of data file.
x (matrix) – array, string or string array, data.
varname (string) – variable name.

Returns:

retcode (scalar) –

return code, 0 if successful, otherwise one of the following error codes:

1	Null file name.
2	File open error.
3	File write error.
4	File read error.
5	Invalid data file type.
8	Variable not found.
10	File contains no variables.
12	File truncate error.
14	File too large to be read on current platform.

Examples#

// Generate random variable x
x = rndn(100, 50);

// Create GDA `myFile`
retcode1 = gdaCreate("myfile.gda", 1);

// Write `x`  to `myfile` as x1
retcode2 = gdaWrite("myfile.gda", x ,"x1");

// Generate random variable y
y = rndn(75, 5);

// Update x1 with y and pack
retcode3 = gdaUpdateAndPack("myfile.gda", y, "x1");

Remarks#

This command updates the variable varname in filename with the data contained in x. gdaUpdateAndPack() always writes the data in x over the specified variable in the file. If x is larger than the specified variable, then it first moves all subsequent data in the file to make room for the new data. If x is smaller, then gdaUpdateAndPack() writes the data, packs all of the subsequent data, leaving no empty bytes after the updated variable, and truncates the file.

This command uses disk space efficiently; however, it may be slow for large files (especially if the variable to be updated is one of the first variables in the file). If speed is a concern, you may want to use gdaUpdate() instead.