Bad formatting using random.sample

I need to take a number n of random lines from a text file, and then write them into a new text file. The code works but the lines are taken and written with a different format than that in the original file, and I want to keep the same. This is the code:

import random

with open('textfile.dat') as f:
    lines = random.sample(f.readlines(),100) #n=100 for example

out=open('newfile.dat', 'w+') 
print >>out, lines

A small part of textfile.dat:

 626.0649 310.7645 122.8257
 626.1954 310.5412 123.0418
 627.0475 310.7212 123.2242
 626.6918 311.0145 123.6525
 ...

And a small part of newfile.dat:

['632.3587 304.9801 101.2915\n', '644.4067 307.2889 114.6692\n', '626.0014 312.0789 98.2628\n', '653.1418 307.1721 100.6861\n', ...

I'm using python 2.7 on macOS. How can I fix it?