import arcpy
import arcpy.sa
# set geoprocessing environments
arcpy.env.workspace = r"H:\MRes\GISProj\2003Imagery\2003Imagery.gdb"
arcpy.env.overwriteOutput = True
from arcpy.sa import *
aprx = arcpy.mp.ArcGISProject(r"H:\MRes\GISProj\2003Imagery\2003Imagery.aprx")
# make new empty list
filteredB4 = []
filteredB2 = []
# iterate original list (.name remove for process)
for lyr in aprx.listMaps()[0].listLayers():
    if lyr.isRasterLayer:
        if "B4" in lyr.name:
            filteredB4.append(lyr)
        if "B2" in lyr.name:
            filteredB2.append(lyr)

# print filtered lists
print (filteredB4)
print (filteredB2)

# zip into tuples
zipped = zip(filteredB4, filteredB2)
list(zip(filteredB4, filteredB2))

# relist
for filteredB4, filteredB2 in zip(filteredB4, filteredB2):
    print(filteredB4)
    print(filteredB2)
    print("NDWI = ", filteredB4)
    print("NDWI = ", filteredB2)
[<arcpy._mp.Layer object at 0x000002732F62A0B8>, <arcpy._mp.Layer object at 0x000002732F62A160>, <arcpy._mp.Layer object at 0x000002732F62ACC0>, <arcpy._mp.Layer object at 0x000002732F62A278>, <arcpy._mp.Layer object at 0x000002732F62A320>, <arcpy._mp.Layer object at 0x000002732F62ABA8>, <arcpy._mp.Layer object at 0x000002732F62A438>, <arcpy._mp.Layer object at 0x000002732F62AAC8>, <arcpy._mp.Layer object at 0x000002732F62A5F8>, <arcpy._mp.Layer object at 0x000002732F62A710>, <arcpy._mp.Layer object at 0x000002732F62AD30>, <arcpy._mp.Layer object at 0x000002732F62ADD8>, <arcpy._mp.Layer object at 0x000002732F62AE80>, <arcpy._mp.Layer object at 0x000002732F62AF60>]
[<arcpy._mp.Layer object at 0x000002732F62A0F0>, <arcpy._mp.Layer object at 0x000002732F62A198>, <arcpy._mp.Layer object at 0x000002732F62AC88>, <arcpy._mp.Layer object at 0x000002732F62A240>, <arcpy._mp.Layer object at 0x000002732F62A390>, <arcpy._mp.Layer object at 0x000002732F62AB70>, <arcpy._mp.Layer object at 0x000002732F62A9E8>, <arcpy._mp.Layer object at 0x000002732F62A470>, <arcpy._mp.Layer object at 0x000002732F62A550>, <arcpy._mp.Layer object at 0x000002732F62A780>, <arcpy._mp.Layer object at 0x000002732F62AD68>, <arcpy._mp.Layer object at 0x000002732F62AE10>, <arcpy._mp.Layer object at 0x000002732F62AEB8>, <arcpy._mp.Layer object at 0x000002732F62AF98>]
Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B4.TIF
Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B2.TIF
NDWI =  Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B4.TIF
NDWI =  Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B2.TIF
Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B4.TIF
Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B2.TIF
NDWI =  Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B4.TIF
NDWI =  Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B2.TIF
Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B4.TIF
Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B2.TIF
NDWI =  Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B4.TIF
NDWI =  Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B2.TIF
Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B4.TIF
Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B2.TIF
NDWI =  Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B4.TIF
NDWI =  Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B2.TIF
Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B4.TIF
Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B2.TIF
NDWI =  Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B4.TIF
NDWI =  Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B2.TIF
Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B4.TIF
Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B2.TIF
NDWI =  Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B4.TIF
NDWI =  Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B2.TIF
Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B4.TIF
Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B2.TIF
NDWI =  Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B4.TIF
NDWI =  Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B2.TIF
Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B4.TIF
Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B2.TIF
NDWI =  Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B4.TIF
NDWI =  Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B2.TIF
Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B4.TIF
Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B2.TIF
NDWI =  Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B4.TIF
NDWI =  Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B2.TIF
Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B4.TIF
Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B2.TIF
NDWI =  Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B4.TIF
NDWI =  Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B2.TIF
Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B4.TIF
Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B2.TIF
NDWI =  Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B4.TIF
NDWI =  Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B2.TIF
Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B4.TIF
Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B2.TIF
NDWI =  Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B4.TIF
NDWI =  Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B2.TIF
Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B4.TIF
Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B2.TIF
NDWI =  Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B4.TIF
NDWI =  Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B2.TIF
Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B4.TIF
Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B2.TIF
NDWI =  Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B4.TIF
NDWI =  Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B2.TIF
import arcpy
import arcpy.sa
# set geoprocessing environments
arcpy.env.workspace = r"H:\MRes\GISProj\2003Imagery\2003Imagery.gdb"
arcpy.env.overwriteOutput = True
from arcpy.sa import *
aprx = arcpy.mp.ArcGISProject(r"H:\MRes\GISProj\2003Imagery\2003Imagery.aprx")
# make new empty list
filteredB4 = []
filteredB2 = []
# iterate original list (.name remove for process)
for lyr in aprx.listMaps()[0].listLayers():
    if lyr.isRasterLayer:
        if "B4" in lyr.name:
            filteredB4.append(lyr)
        if "B2" in lyr.name:
            filteredB2.append(lyr)

# print filtered lists
print (filteredB4)
print (filteredB2)

# zip into tuples
zipped = zip(filteredB4, filteredB2)
list(zip(filteredB4, filteredB2))

# relist
for filteredB4, filteredB2 in zip(filteredB4, filteredB2):
    print("NDWI = ", filteredB4)
    print("NDWI = ", filteredB2)
[<arcpy._mp.Layer object at 0x000002732F62A3C8>, <arcpy._mp.Layer object at 0x000002732F62A4A8>, <arcpy._mp.Layer object at 0x000002732F62ACF8>, <arcpy._mp.Layer object at 0x000002732F62AF28>, <arcpy._mp.Layer object at 0x000002732F62A9B0>, <arcpy._mp.Layer object at 0x000002732F62C0B8>, <arcpy._mp.Layer object at 0x000002732F62C160>, <arcpy._mp.Layer object at 0x000002732F62C208>, <arcpy._mp.Layer object at 0x000002732F62C2E8>, <arcpy._mp.Layer object at 0x000002732F62C390>, <arcpy._mp.Layer object at 0x000002732F62C438>, <arcpy._mp.Layer object at 0x000002732F62C4E0>, <arcpy._mp.Layer object at 0x000002732F62C5F8>, <arcpy._mp.Layer object at 0x000002732F62C6D8>]
[<arcpy._mp.Layer object at 0x000002732F62AB00>, <arcpy._mp.Layer object at 0x000002732F62A630>, <arcpy._mp.Layer object at 0x000002732F62ADA0>, <arcpy._mp.Layer object at 0x000002732F62AEF0>, <arcpy._mp.Layer object at 0x000002732F62C048>, <arcpy._mp.Layer object at 0x000002732F62C0F0>, <arcpy._mp.Layer object at 0x000002732F62C198>, <arcpy._mp.Layer object at 0x000002732F62C240>, <arcpy._mp.Layer object at 0x000002732F62C2B0>, <arcpy._mp.Layer object at 0x000002732F62C3C8>, <arcpy._mp.Layer object at 0x000002732F62C470>, <arcpy._mp.Layer object at 0x000002732F62C518>, <arcpy._mp.Layer object at 0x000002732F62C630>, <arcpy._mp.Layer object at 0x000002732F62C710>]
NDWI =  Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B4.TIF
NDWI =  Dec\216111\LE07_L1GT_216111_20021211_20170127_01_T2_B2.TIF
NDWI =  Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B4.TIF
NDWI =  Dec\216110\LE07_L1GT_216110_20021211_20170128_01_T2_B2.TIF
NDWI =  Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B4.TIF
NDWI =  Dec\218109\LE07_L1GT_218109_20021225_20170127_01_T2_B2.TIF
NDWI =  Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B4.TIF
NDWI =  Dec\218110\LE07_L1GT_218110_20021225_20170127_01_T2_B2.TIF
NDWI =  Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B4.TIF
NDWI =  Jan\218110\LE07_L1GT_218110_20030126_20170126_01_T2_B2.TIF
NDWI =  Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B4.TIF
NDWI =  Jan\218111\LE07_L1GT_218111_20030126_20170126_01_T2_B2.TIF
NDWI =  Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B4.TIF
NDWI =  Jan\219109\LE07_L1GT_219109_20030117_20170127_01_T2_B2.TIF
NDWI =  Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B4.TIF
NDWI =  Jan\219110\LE07_L1GT_219110_20030117_20170127_01_T2_B2.TIF
NDWI =  Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B4.TIF
NDWI =  Jan\215111\LE07_L1GT_215111_20030105_20170128_01_T2_B2.TIF
NDWI =  Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B4.TIF
NDWI =  Feb\218110\LE07_L1GT_218110_20030211_20170126_01_T2_B2.TIF
NDWI =  Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B4.TIF
NDWI =  Feb\216111\LE07_L1GT_216111_20030213_20170126_01_T2_B2.TIF
NDWI =  Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B4.TIF
NDWI =  Feb\216110\LE07_L1GT_216110_20030213_20170126_01_T2_B2.TIF
NDWI =  Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B4.TIF
NDWI =  Feb\215111\LE07_L1GT_215111_20030222_20170126_01_T2_B2.TIF
NDWI =  Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B4.TIF
NDWI =  Mar\216111\LE07_L1GT_216110_20030301_20170127_01_T2_B2.TIF