Friday, January 7, 2011

[DBN] Learning multiple layers of Features from tiny images

In this paper, there are more detailed equation derivations for RBM, especially the Gaussian-Bernoulli RBM.

 

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Wednesday, January 5, 2011

Matlab v7.3 mat file and python

From: http://mloss.org/community/blog/2009/nov/19/matlabtm-73-file-format-is-actually-hdf5-and-can-b/

It looks like that matlab version 7.3 and later are capable of writing out objects in the so called matlab 7.3 file format. While at first glance it looks like another proprietary format - it seems to be in fact the Hierarchical Data Format version 5 or in short hdf5.

So you can do all sorts of neat things:

  1. Lets create some matrix in matlab first and save it:

    >> x=[[1,2,3];[4,5,6];[7,8,9]] x = 1 2 3 4 5 6 7 8 9 >> save -v7.3 x.mat x
  2. Lets investigate that file from the shell:

    $ h5ls x.mat x Dataset {3, 3} $ h5dump x.mat HDF5 "x.mat" { GROUP "/" { DATASET "x" { DATATYPE H5T_IEEE_F64LE DATASPACE SIMPLE { ( 3, 3 ) / ( 3, 3 ) } DATA { (0,0): 1, 4, 7, (1,0): 2, 5, 8, (2,0): 3, 6, 9 } ATTRIBUTE "MATLAB_class" { DATATYPE H5T_STRING { STRSIZE 6; STRPAD H5T_STR_NULLTERM; CSET H5T_CSET_ASCII; CTYPE H5T_C_S1; } DATASPACE SCALAR DATA { (0): "double" } } } } }
  3. And load it from python:

    >>> import h5py >>> import numpy >>> f = h5py.File('x.mat') >>> x=f["x"] >>> x <HDF5 dataset "x": shape (3, 3), type "<f8"> >>> numpy.array(x) array([[ 1., 4., 7.], [ 2., 5., 8.], [ 3., 6., 9.]])

So it seems actually to be a good idea to use matlab's 7.3 format for interoperability.

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Thursday, December 23, 2010

[ASR] Still Tandem systems

The attached paper models phonetic attributes with CRF models. However, the sentence interests me most is the following one:

As described in [1] we used the linear output of the MLPs with a KL transform applied to them to decorrelate the features, as this gave the best results for the HMM system.

[1] H. Hermansky, D. Ellis, and S. Sharma, "Tandem connectionist feature stream extraction for conventional HMM systems", in Proc. of the ICASSP 2000.

Maybe sometime we could also try to refine the posterior features from NN for HMM systems. 

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Monday, December 20, 2010

[Linux] Mac configure type

In many cases the build step involves running a configure script. Occasionally you'll run a configure script that gives error message stating that the host type cannot be determined. In such a case, you can usually either specify the configure option --host=powerpc-apple-darwin6.4 as I've done in the examples below. (Note in this case, we are using darwin6.4. To determine the correct release of darwin, enter the command uname -r.) You can alternatively copy two files into the build directory, that is, into the same directory that contains the script configure. 

Code:
cp /usr/share/libtool/config.guess . cp /usr/share/libtool/config.sub .
Occasionally, the configure option --build=powerpc-apple-darwin6.4 is needed to produce the desired result (again assuming we're using darwin release 6.4). 

In some cases, there are additional steps to be performed. ...

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