Can you load matlab data in python?
Show Matlab is a really popular platform for scientific computing in the academia. I’ve used it my throughout my engineering degree and chances are, you will come across .mat files for datasets released by the universities. This is a brief post which explains how to load these files using python, the most popular language for machine learning today. The dataI wanted to build a classifier for detecting cars of different models and makes and so the Stanford Cars Dataset appeared to be a great starting point. Coming from the academia, the annotations for the dataset was in the .mat format. You can get the file used in this post here. Loading .mat filesScipy is a really popular python library used for scientific computing and quite naturally, they have a method which lets you read in .mat files. Reading them in is definitely the easy part. You can get it done in one line of code: from scipy.io import loadmat
Well, it’s really that simple. But let’s go on and actually try to get the data we need out of this dictionary. Formatting the dataThe loadmat method returns a more familiar data structure, a python dictionary. If we peek into the keys, we’ll see how at home we feel now compared to dealing with a .mat file: annots.keys() Looking at the documentation for this dataset, we’ll get to learn what this is really made of. The README.txt gives us the following information: This file gives documentation for the cars 196 dataset. Our interest is in the 'annotations' variable, as it contains our class labels and bounding boxes. It’s a struct, a data type very familiar to folks coming from a strongly typed language like a flavour of C or java. A little digging into the object gives us some interesting things to work with: type(annots[‘annotations’]),annots[‘annotations’].shape The annotations are stored in a numpy.ndarray format, however the data type for the items inside this array is numpy.void and numpy doesn’t really seem to know the shape of them. The documentation page for the loadmat method tells us how it loads matlab structs into numpy structured arrays.You can access the members of the structs using the keys: annots[‘annotations’][0][0][‘bbox_x1’], annots[‘annotations’][0][0][‘fname’]> (array([[39]], dtype=uint8), array(['00001.jpg'], dtype=' So now that we know how to access the members of the struct, we can iterate through all of them and store them in a list: [item.flat[0] for item in annots[‘annotations’][0][0]]> [39, 116, 569, 375, 14, '00001.jpg'] Here, we can use the flat method to squeeze the value out of the array. Hello PandasNow that we know how to deal with matlab files in python, let’s convert it into a pandas data frame. We can do so easily using a list of lists: data = [[row.flat[0] for row in line] for line in annots[‘annotations’][0]]columns = [‘bbox_x1’, ‘bbox_y1’, ‘bbox_x2’, ‘bbox_y2’, ‘class’, ‘fname’] Finally, familiar territory! The code for this post can be found here. Can you open MATLAB files in Python?Matlab 7.3 and greater
These files can be read in Python using, for instance, the PyTables or h5py package.
How do I open a .MAT file in Python?How to read .. Install scipy. Similar to how we use the CSV module to work with . ... . Import the scipy. io. ... . Parse the . mat file structure. ... . Use Pandas dataframes to work with the data. Now that you have the information and the data retrieved, how would you work with it?. How do I convert MATLAB code to Python?To convert Matlab to python, we have two options, either do it manually or take the help of some tool. To convert Matlab to python, a tool named SMOP (Small Matlab and Octave to Python Compiler) is used. This tool is capable of understanding basic Matlab code and then parsing it to python.
How do I open a .MAT file without MATLAB?. mat files contain binary data, so you will not be able to open them easily with a word processor. There are some options for opening them outside of MATLAB: If all you need to do is look at the files, you could obtain Octave, which is a free, but somewhat slower implementation of MATLAB.
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