Write a raw binary file with NumPy array data
Question:
I’d like to save the contents of a numpy float array into a raw binary file as signed 16 bit integers. I tried to accomplish this using ndarray.tofile but I can’t figure out the right format string. It seems that the file is saved in double format, mo matter how I choose the format string. How do I do this?
Thanks.
Answers:
I think the easiest way to do this is to first convert the array to int16,
array.astype('int16').tofile(filename)
Take a look at the struct module, try this example:
import struct
import numpy
f=open("myfile","wb")
mydata=numpy.random.random(10)
print(mydata)
myfmt='f'*len(mydata)
# You can use 'd' for double and < or > to force endinness
bin=struct.pack(myfmt,*mydata)
print(bin)
f.write(bin)
f.close()
You may use scipy.io.savemat which allows to save a dictionary of names and arrays into Matlab-style file:
import scipy.io as sio
sio.savemat(filename, pydict)
Here pydict may be = {‘name1’:np.array1, ‘name2’:np.array2,…}
To load the dict you just need:
pydict = sio.loadmat(filename)
I’d like to save the contents of a numpy float array into a raw binary file as signed 16 bit integers. I tried to accomplish this using ndarray.tofile but I can’t figure out the right format string. It seems that the file is saved in double format, mo matter how I choose the format string. How do I do this?
Thanks.
I think the easiest way to do this is to first convert the array to int16,
array.astype('int16').tofile(filename)
Take a look at the struct module, try this example:
import struct
import numpy
f=open("myfile","wb")
mydata=numpy.random.random(10)
print(mydata)
myfmt='f'*len(mydata)
# You can use 'd' for double and < or > to force endinness
bin=struct.pack(myfmt,*mydata)
print(bin)
f.write(bin)
f.close()
You may use scipy.io.savemat which allows to save a dictionary of names and arrays into Matlab-style file:
import scipy.io as sio
sio.savemat(filename, pydict)
Here pydict may be = {‘name1’:np.array1, ‘name2’:np.array2,…}
To load the dict you just need:
pydict = sio.loadmat(filename)