test_NumExpr.py

# coding: utf-8
import numpy
from hashlib import md5
from tables.utilsExtension import get_nested_field
import numexpr

from numexpr.necompiler import NumExpr, stringToExpression
import tables

FILENAME = '/data/hisparc/corsika/corsika_overview.h5'

def do_md5(args):
    m = md5()
    for arg in args:
        m.update(arg)
    return m.hexdigest()


def makeNumExpr():
    """ Make a NumExpr object exactly as pytables """

    mysig = [('energy', float)]
    print 'mysig ', mysig

    typemap = {'energy': float}
    strexpr = stringToExpression('log10(energy) >= 14.', typemap, {})
    print "strexpr ", strexpr

    return NumExpr(strexpr, mysig)


if __name__ == '__main__':
    print "numexpr version: ", numexpr.__version__
    expr = makeNumExpr()

    data = tables.open_file(FILENAME, 'r')
    e = data.root.simulations.col('energy')
    dt = [('energy', numpy.float32)]
    energy = numpy.array(e, dtype=dt)
    #print energy

    #print expr.program.encode('hex')
    #print expr.signature
    #print expr.input_names
    #print sum(expr.run(energy))

    recarrs = [energy, data.root.simulations.read()]
    for recarr in recarrs:
        print "next array"
        print "type of recarr", type(recarr)
        field = get_nested_field(recarr, 'energy')
        print "sum field: ", sum(field)
        print "type of field: ", type(field)
        print "md5 hash of field: ", do_md5(*[field])
        # this is the call pytables makes in tables.conditions.call_on_recarray()
        print sum(expr(*[field]))