MATLAB Programming

Hierarchical Data Format (HDF4) Files
If it can write the data to the data set, SDwritedata returns 0; otherwise,
it returns -1.
Note SDwritedata queues write operations. To ensure that these queued
write operations are executed, you must close the file, using the SDend routine.
See “Step 6: Closing an HDF4 File” on page 7-70 for more information. As a
convenience, MATLAB provides a function, MLcloseall, thatyoucanuseto
close all open data sets and file identifiers with a single call. See “Using the
MATLAB HDF4 Utility API” on page 7-70 for more information.
To write less than the entire data set, use the start, stride, and edges vectors
to specify where you want to start writing data and how much data you want
to write.
For example, the following code fragment uses SDwritedata to replace the
values of the entire second row of the sample data set:
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
with the vector B:
B = [ 9 9 9 9 9];
In the example, the start vector specifies that you want to start the write
operationinthefirstcolumnofthe second row. Note how HDF4 uses
zero-based indexing and specifies the column dimension first. In MATLAB,
you would specify this location as (2,1). The edges argument specifies the
dimensions of the data to be written. Note that the size of the array of data
to be written must match the edgespecification.
ds_start = [0 1]; % Start writing at the first column, second row.
ds_stride = []; % Write every element.
ds_edges = [5 1]; % Each row is a 1-by-5 vector.
stat = hdfsd('writedata',sds_id,ds_start,ds_stride,ds_edges,B);
7-67