How can I write double precision files binary files using Python? I am doing the following presently but it is giving me single precision files:
#!/usr/bin/env python
import struct
data =[2.3715231753176,9.342983274982732]
output_file = "test.dat"
out_file = open(output_file,"wb")
s = struct.pack('f'*len(data), *data)
out_file.write(s)
out_file.close()
Use d to write double precision floats:
s = struct.pack('d'*len(data), *data)
f is single precision only. See the Format characters section of the struct module documentation:
For the
'f'and'd'conversion codes, the packed representation uses the IEEE 754 binary32 (for'f') or binary64 (for'd') format, regardless of the floating-point format used by the platform.
struct.pack(), and the issue was not binary data writing in general, but writing floating point values.You're using the format string wrongly. To use double precision, use 'd' instead of 'f'. See the documentation for a list of format characters.
