scipy tutorial - Baustatik-Info-Server

octave:11> my_struct = struct(’field1’, 1, ’field2’, 2)
my_struct =
{
field1 = 1
field2 = 2
}
octave:12> save -6 octave_struct.mat my_struct
We can load this in Python:
SciPy Reference Guide, Release 0.8.dev
>>> mat_contents = sio.loadmat(’octave_struct.mat’)
>>> print mat_contents
{’my_struct’: array([[]], dtype=object), ’__vers
>>> oct_struct = mat_contents[’my_struct’]
>>> print oct_struct.shape
(1, 1)
>>> val = oct_struct[0,0]
>>> print val
>>> print val.field1
[[ 1.]]
>>> print val.field2
[[ 2.]]
In this version of Scipy (0.7.1), Matlab structs come back as custom objects, called mat_struct, with attributes
named for the fields in the structure. Note also:
>>> val = oct_struct[0,0]
and:
octave:13> size(my_struct)
ans =
1 1
So, in Matlab, the struct array must be at least 2D, and we replicate that when we read into Scipy. If you want all
length 1 dimensions squeezed out, try this:
>>> mat_contents = sio.loadmat(’octave_struct.mat’, squeeze_me=True)
>>> oct_struct = mat_contents[’my_struct’]
>>> oct_struct.shape # but no - it’s a scalar
Traceback (most recent call last):
File "", line 1, in
AttributeError: ’mat_struct’ object has no attribute ’shape’
>>> print oct_struct
>>> print oct_struct.field1
1.0
Saving struct arrays can be done in various ways. One simple method is to use dicts:
>>> a_dict = {’field1’: 0.5, ’field2’: ’a string’}
>>> sio.savemat(’saved_struct.mat’, {’a_dict’: a_dict})
1.11. File IO (scipy.io) 83