haddsplit

#!/usr/bin/env python

import sys, os

def haddsplit(destDir, inputFiles):
    ## estimate total size and merge not to exceed 1Gbytes
    totalSize = sum([os.stat(f).st_size for f in inputFiles])
    fSize = 4*1024.*1024*1024 # 4GB
    nOutput = int(totalSize/fSize)+1

    nTotalFiles = len(inputFiles)
    nFiles = nTotalFiles/nOutput

    for i in range(nOutput):
        print i
        cmd = 'hadd -f %s_%d.root ' % (destDir, i)
        if i == nOutput-1: cmd += ' '.join(inputFiles[i*nFiles:])
        else: cmd += ' '.join(inputFiles[i*nFiles:(i+1)*nFiles])
        os.system(cmd)
    for x in inputFiles: os.system("rm -f %s" % (x))

def usage():
    print """usage: %s OUTPUT.root INPUT_0.root INPUT_1.root ...

OUTPUT root files will be split by 4GBytes,
OUTPUT_0.root OUTPUT_1.root ... will be created""" % (sys.argv[0])

if __name__ == '__main__':
    if len(sys.argv) < 3:
        usage()
        sys.exit(1)

    outFilePrefix = sys.argv[1].replace('.root', '')
    inFileNames = sys.argv[2:]

    if len(inFileNames) == 1:
        os.system("mv %s %s_0.root" % (inFileNames[0], outFilePrefix))
    else:
        haddsplit(outFilePrefix, inFileNames)