# structwrite.py
#
# An example of writing a binary-packed data structure
from timethis import timethis
import struct
from random import random
# Create a million random (x,y) points
points = [(random(),random()) for n in range(1000000)]
# Write out to a file using write() and struct.pack()
with timethis("Writing many small structs"):
 f = open("pts1.bin","wb")
 f.write(struct.pack("I",len(points)))
 for p in points:
 f.write(struct.pack("ff",*p))
 f.close()
# Pack a bytearray and write it all at once
with timethis("Packing a bytearray and writing"):
 out = bytearray()
 out.extend(struct.pack("I",len(points)))
 for p in points:
 out.extend(struct.pack("ff",*p))
 f = open("pts2.bin","wb")
 f.write(out)
 f.close()
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