import arcpy
import string
from  math import *
from arcpy import *
from arcpy.sa import *
import os
from os import listdir
from os.path import join

arcpy.CheckOutExtension("spatial")

BP = "H:\NorthSea\Images4AllDates\BPnoEo\"
Eo = "C:\Users\robyn\Desktop\NCEPre2\Watts2Eo\"
output = "C:\Users\robyn\Desktop\FinalPPresults\"
arcpy.env.cellSize = "MINOF"

netSW = os.listdir(Eo)
chlKd = os.listdir(BP)

for files in netSW and chlKd:
    SW = os.path.join(Eo, files)
    filenameSW = SW[40:48]
    CC = os.path.join(BP, files)
    filenameCC = CC[35:43]
    if files.endswith(".img"):
        if (files in SW[40:48]) == (files in CC[35:43]):
        #or if filenameSW == filenameCC:
            Output = output + files
            BPI = Raster(SW) * Raster(CC)
            BPI.save(Output)
            print Output + " done"

for files in (netSW and chlKd):

import arcpy
import string
from  math import *
from arcpy import *
from arcpy.sa import *
import os
from os import listdir
from os.path import join
import re

arcpy.CheckOutExtension("spatial")
arcpy.env.cellSize = "MINOF"

BP = "H:\NorthSea\Images4AllDates\BPnoEo\"
Eo = "C:\Users\robyn\Desktop\NCEPre2\Watts2Eo\"
output = "C:\Users\robyn\Desktop\FinalPPresults\"

netSW = os.listdir(Eo)
chlKd = os.listdir(BP)

netSW_regex = re.compile("([0-9]{8}).img") # matches 20020101_105433.img
chlKd_regex = re.compile("([0-9]{8})_([0-9]{6}).img") # matches 20020102.img

for fileSW in netSW:
    for fileCC in chlKd:
        SW = os.path.join(Eo, fileSW)
        CC = os.path.join(BP, fileCC)

        netSW_matcher = netSW_regex.match(fileSW)
        chlKd_matcher = chlKd_regex.match(fileCC)
        if netSW_matcher and chlKd_matcher and netSW_matcher.group(1) == chlKd_matcher.group(1):
            print "Multiplying {} and {}".format(fileSW, fileCC)
            target_path = os.path.join(result, fileSW)
            BPI = Raster(SW) * Raster(CC)
            BPI.save(target_path)
            print "Done {}".format(target_path)