Loading the binary data to a NumPy array

I am having trouble reading the binary file. I have a NumPy array as,

data = array([[ 0.        ,  0.        ,  7.821725  ],
              [ 0.05050505,  0.        ,  7.6358337 ],
              [ 0.1010101 ,  0.        ,  7.453858  ],
              ...,
              [ 4.8989897 ,  5.        , 16.63227   ],
              [ 4.949495  ,  5.        , 16.88153   ],
              [ 5.        ,  5.        , 17.130795  ]], dtype=float32)

I wrote this array to a file in binary format.

file = open('model_binary', 'wb')
data.tofile(file)

Now, I am unable to get back the data from the saved binary file. I tried using numpy.fromfile() but it didn’t work out for me.

file = open('model_binary', 'rb')
data = np.fromfile(file)

When I printed the data I got [0.00000000e+00 2.19335211e-13 8.33400000e+04 ... 2.04800049e+03 2.04800050e+03 5.25260241e+07] which is absolutely not what I want.

I ran the following code to check what was in the file,

for line in file:
    print(line)
    break

I got the output as b'x00x00x00x00......c1x07@x00x00x00x00Sxc5{@jxfdn' which I suppose is in binary format.

I would like to get the array back from the binary file as it was saved. Any help will be appreciated.

Answer

As Kevin noted, adding the dtype is required. You might also need to reshape (you have 3 columns in your example. So

file = open('model_binary', 'rb')
data = fromfile(file, dtype=np.float32).reshape((-1,3))

should work for you.

As an aside, I think np.save does save to binary format, and should avoid these issues.

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Answer