Problems with global variables ((python))

Question

I have a problem with my global variables in my code. In SCRIPT1.py I use many variables from a little document config.py which only contains variables which I also need in other modules of my code. But when running my SCRIPT1.py I get an error (ERROR). I have no idea why it doesn't work with config.(name of variable)... I found this solution to have your variables in all of your modules on stack overflow with a lot of good votes. What am I doing wrong?

First my code contained config.costSurfaceA in stead of costSurfaceArray (for ex in 'def createPath') but when running it with this variable, it gave me a syntax error because of the dot in 'config.costSurfaceA'. I replaced it all by 'costSurfaceArray' and did this in the if statement 'config.costSurfaceA = costSurfaceArray' just to get it as a variable. But I have the feeling this is all to much work for nothing..

Thanks in avance for helping me! I know it is a lot of code but I think it's all important for understanding..

SCRIPT1.py

from osgeo import gdal, osr
from skimage.graph import route_through_array
import numpy as np
import Save_Array_To_Excel_01
import config

def ask_costsurfacepath_path():
    config.costsurfacepath = input('please enter the system path where to find the cost-surface-IMG file (ex: /Users/PeterVanvoorden/Documents/GroepT/Thesis/Branched_Testfile.img): ')

def ask_outputpath_path():
    config.outputpath = input('please enter the system path where to save the outputpath IMG file (ex: /Users/PeterVanvoorden/Documents/GroepT/Thesis/Branched_Testfile.img): ')


def raster2array(rasterfn):
    print 'raster2array'
    raster = gdal.Open(rasterfn)
    band = raster.GetRasterBand(1)
    array = band.ReadAsArray()
    return array  

def coord2pixelOffset(rasterfn,x,y):
    print 'coord2pixelOffset'
    raster = gdal.Open(rasterfn)
    geotransform = raster.GetGeoTransform()
    originX = geotransform[0] # East/West location of Upper Left corner
    originY = geotransform[3] # North/South location of Upper Left corner
    pixelWidth = geotransform[1] # X pixel size
    pixelHeight = geotransform[5] # Y pixel size
    xOffset = int((x - originX)/pixelWidth)
    yOffset = int((y - originY)/pixelHeight)
    return xOffset,yOffset

def createPath(CostSurfacefn,costSurfaceArray,startCoord,stopCoord):   
    print 'creatpath'
    # coordinates to array index
    startCoordX = startCoord[0]
    startCoordY = startCoord[1]
    startIndexX,startIndexY = coord2pixelOffset(CostSurfacefn,startCoordX,startCoordY)

    stopCoordX = stopCoord[0]
    stopCoordY = stopCoord[1]
    stopIndexX,stopIndexY = coord2pixelOffset(CostSurfacefn,stopCoordX,stopCoordY)

    # create path
    indices, weight = route_through_array(costSurfaceArray, (startIndexY,startIndexX), (stopIndexY,stopIndexX),geometric=True,fully_connected=True)
    indices = np.array(indices).T
    path = np.zeros_like(costSurfaceArray)
    path[indices[0], indices[1]] = 1
    return path

def array2raster(newRasterfn,rasterfn,array):
    print 'array2raster'
    raster = gdal.Open(rasterfn)
    geotransform = raster.GetGeoTransform()
    originX = geotransform[0] # East/West location of Upper Left corner
    originY = geotransform[3] # North/South location of Upper Left corner
    pixelWidth = geotransform[1] # X pixel size
    pixelHeight = geotransform[5] # Y pixel size
    cols = array.shape[1]
    rows = array.shape[0]

    driver = gdal.GetDriverByName('GTiff')
    outRaster = driver.Create(newRasterfn, cols, rows, gdal.GDT_Byte)
    outRaster.SetGeoTransform((originX, pixelWidth, 0, originY, 0, pixelHeight))
    outband = outRaster.GetRasterBand(1)
    outband.WriteArray(array)
    outRasterSRS = osr.SpatialReference()
    outRasterSRS.ImportFromWkt(raster.GetProjectionRef())
    outRaster.SetProjection(outRasterSRS.ExportToWkt())
    outband.FlushCache()    

def main(CostSurfacefn,outputPathfn,startCoord,stopCoord):

    print 'main'

    costSurfaceArray = raster2array(CostSurfacefn) # creates array from cost surface raster

    config.costSurfaceA = costSurfaceArray

    config.pathArray = createPath(CostSurfacefn,costSurfaceArray,startCoord,stopCoord) # creates path array

    Save_Array_To_Excel_01.Save_Array(config.pathArray) # Save Array to csv file

    array2raster(outputPathfn,CostSurfacefn,config.pathArray) # converts path array to raster


if __name__ == "__main__":

    ask_costsurfacepath_path()
    ask_outputpath_path()
    CostSurfacefn = config.costsurfacepath
    print config.costsurfacepath
    startCoord = (config.startX,config.startY)
    stopCoord = (config.stopX,config.stopY)
    outputPathfn = config.outputpath

    main(CostSurfacefn,outputPathfn,startCoord,stopCoord)

config.py

# Configuration file with all global variables

# number of properties
number =  None

# different permutations of properties
permutations = list()

# properties array containing:
# * first column = ID first property [0]
# * second column = ID second property [1]
# * third column = distance between two properties [2]
# * forth column = estimated cost [3]
properties_array = None

# lowest price until now
lowest_price = 10**10000

# path with this lowest price
lowest_path = None

# current price (needs to be compared with lowest price)
current_price = 0

# current path (needs to be compared with lowest path)
current_path = [1]

# path to place where to save properties list
plist_path = None

# Array of the path
pathArray = None

# Array of the map
costSurfaceA = None

# current start X coordinate
startX = 0

# current start Y coordinate
startY = 0

# current stop X coordinate
stopX = 0

# current stop Y coordinate
stopY = 0

# path to costsurface IMG file
costsurfacepath = 0

# path to output path from Least cost path analysis
outputpath = 0

ERROR

please enter the system path where to put the file as a STRING (ex: /Users/PeterVanvoorden/Documents/GroepT/Thesis/Branched_Testfile.csv): '/User/PeterVanvoorden/Desktop/Shell.csv'

You entered: /User/PeterVanvoorden/Desktop/Shell.csv

please enter the system path where to find the cost-surface-IMG file (ex: /Users/PeterVanvoorden/Documents/GroepT/Thesis/Branched_Testfile.img): '/User/PeterVanvoorden/Desktop/clipsmall.img'
please enter the system path where to save the outputpath IMG file (ex: /Users/PeterVanvoorden/Documents/GroepT/Thesis/Branched_Testfile.img): '/User/PeterVanvoorden/Desktop/Shellimg.img'
/User/PeterVanvoorden/Desktop/clipsmall.img
main
raster2array

Traceback (most recent call last):
  File "/Users/PeterVanvoorden/Documents/GroepT/Thesis/f_python_standalone/python_files/Working_Files/Least_cost_path_analysis_01_outputArray.py", line 97, in <module>
    main(CostSurfacefn,outputPathfn,startCoord,stopCoord)
  File "/Users/PeterVanvoorden/Documents/GroepT/Thesis/f_python_standalone/python_files/Working_Files/Least_cost_path_analysis_01_outputArray.py", line 76, in main
    costSurfaceArray = raster2array(CostSurfacefn) # creates array from cost surface raster
  File "/Users/PeterVanvoorden/Documents/GroepT/Thesis/f_python_standalone/python_files/Working_Files/Least_cost_path_analysis_01_outputArray.py", line 17, in raster2array
    band = raster.GetRasterBand(1)
AttributeError: 'NoneType' object has no attribute 'GetRasterBand'

Answer 1

You can pass around like this.

def ask_costsurfacepath_path():
    costsurfacepath = input('please enter ...')
    return costsurfacepath

... in __name__ == '__main__'
CostSurfacefn = ask_costsurfacepath_path()
...