#!/usr/bin/env python
from pyPdf import PdfFileWriter, PdfFileReader

output = PdfFileWriter()
inputleft = PdfFileReader(file("document1.pdf", "rb"))
inputright = PdfFileReader(file("document1.pdf", "rb"))

def LeftHalfPage(p):
    p.mediaBox.upperRight = (
        p.mediaBox.getUpperRight_x() / 2,
        p.mediaBox.getUpperRight_y()
        )
    return p

def RightHalfPage(p):
    p.mediaBox.lowerLeft = (
        p.mediaBox.getUpperRight_x() / 2,
        p.mediaBox.getLowerLeft_y()
        )
    return p

###########################################################
output.addPage(LeftHalfPage(inputleft.getPage(0)))
endPage = RightHalfPage(inputright.getPage(0))

for i in range(1, inputleft.getNumPages()):
    output.addPage(LeftHalfPage(inputleft.getPage(i)))
    output.addPage(RightHalfPage(inputright.getPage(i)))

output.addPage(endPage)

# print how many pages input1 has:
print "document1.pdf has %s pages." % inputleft.getNumPages()

# finally, write "output" to document-output.pdf
outputStream = file("document-output.pdf", "wb")
output.write(outputStream)
outputStream.close()