MATLAB Programming

6 Data Import and Export
IfthefiletobemappedresidessomewhereontheMATLABpath,youcanuse
a partial pathname. If the path to the file is not fully specified, MATLAB
searches for the file in your current working directory first, and then on the
MATLAB path.
Once memmapfile locates the file, MATLAB stores the absolute pathname for
the file internally, and then uses this stored path to locate the file from that
point on. This enables you to work in other directories outside your current
work directory and retain access to the mapped file.
You can change the value of the Filename property at any time after
constructing the memmapfile object. You might want to do this if
• You want to use the same memmapfile object on more than one file.
• You save your memmapfile object to a MAT-file, and then later load it back
into MATLAB in an environment where themappedfilehasbeenmovedto
a different location. This requires that you modify the path segment of the
Filename string to represent the new location.
For example, save memmapfile object m to file mymap.mat:
disp(m.Filename)
d:\matlab\mfiles\records.dat
save mymat m
Now move the file to another location, load the object back into MATLAB, and
update the path in the Filename property:
load mymat m
m.Filename = 'f:\testfiles\oct1\records.dat'
Note You can only map an existing file. You cannot create a new file and map
that file to memory in one operation. UsetheMATLABfileI/Ofunctionsto
create the file before attempting to map it to memory.
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