How to split data into trainset and testset randomly?

Question

I have a large dataset and want to split it into training(50%) and testing set(50%).

Say I have 100 examples stored the input file, each line contains one example.

Answer 1

sklearn.cross_validation is deprecated since version 0.18, instead you should use sklearn.model_selection as show below

from sklearn.model_selection import train_test_split
import numpy

with open("datafile.txt", "rb") as f:
   data = f.read().split('\n')
   data = numpy.array(data)  #convert array to numpy type array

   x_train ,x_test = train_test_split(data,test_size=0.5)       #test_size=0.5(whole_data)