problem with saving dataset

Loading a dataset and saving it directly without any other variables in workspace generates a much bigger file . 1.387 Mb becomes a matfile of 137.751 Mb. Any reason for this? Matlab version 7.3 is used for saving.

[Jaap]

did you look at things like format (xls,txt,...) and to data types (doubles, integers...)?

Answer 1

[Matt Tearle]

What is the size of the variable in the workspace? (You can run whos to see this info.)

If it's ~137 Mb then my guess is that it's something to do with the type of file you're reading from and/or the type of data that allows it to be compressed or stored in a small amount of memory, but when you're bringing it into MATLAB it's probably using "large-footprint" types like doubles. Simple example to explain what I mean:

1 2 3 4
2 3 4 5
3 4 5 6
4 5 6 7

saved as a text file is only 36 bytes. Read it into MATLAB and it will be a 4-by-4 array of doubles => it's 16*8 = 128 bytes.