Hi, I want to read binary data from a file using fromfile. This works as long as I use a file name as argument to fromfile. With a file object the data is wrong! Consider the following example: from numpy import * fname='file.bin' fname2='file2.bin' a = arange(1, 30) print type(a[0]) print "\noriginal data" print a # write to file name a.tofile(fname) # write to file object f = open(fname2, 'w') a.tofile(f) f.close() print "\nWritten to file name, read from file name" b = fromfile(fname, dtype=int32) print b print "\nWritten to file name, read from file object" f = open(fname, 'r') b = fromfile(f, dtype=int32) f.close() print b print "\nWritten to file object, read from file name" b = fromfile(fname2, dtype=int32) print b print "\nWritten to file object, read from file object" f = open(fname2, 'r') b = fromfile(f, dtype=int32) f.close() print b This prints: <type 'numpy.int32'> original data [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29] Written to file name, read from file name [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29] Written to file name, read from file object [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 0 0 0 0] Written to file object, read from file name [ 1 2 3 4 5 6 7 8 9 2573 2816 3072 3328 3584 3840 4096 4352 4608 4864 5120 5376 5632 5888 6144 6400 6656 6912 7168 7424] Written to file object, read from file object [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 0 0 0 0] Size of 'file.bin' (written to file name) is 116 Bytes, size of 'file2.bin' (written to file object) is 117 Bytes! So the only correct data is when writing to a file name and reading from a file name. All other variants yield wrong data! This happens with Numpy 1.4.1 with Python 2.6 under Windows XP. For comparison I only have a 1.1.0 Numpy with Python 2.5 under Linux Debian where in all cases I get the same, correct arrays! Am I doing something substantially wrong or is this a bug? Christoph