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pythonlistobjectargs

Python : Manipulating Arguments from a list of objects.


So I have the following code. The merge_files() function basically merges two files (strings) and returns a list. This list is used to feed arguments from an object.

file1

['2.02', '-3.88', '15.25']
['4.40', '-2.36', '14.97']

file2

['P1']
['P2']

The problem is that when giving the values directly to the object, the function grade_compass() works fine. When the object pulls the same values from the parser, it doesnt seem to go through this function.

whole code:

    from ast import literal_eval


class Compass:

   #initialize the attributes
    def __init__(self, coordX, coordY, coordZ, Pos):
        self.coordx = coordX
        self.coordy = coordY
        self.coordz = coordZ
        self.coord_pos = Pos



def merge_files(infile1, infile2):
    with open(infile1) as f1, open(infile2) as f2:
        l3 = [] # this is a list for storing all the lines from both files
        f1_lists = (literal_eval(line) for line in f1)
        f2_lists = (literal_eval(line) for line in f2)
        for l1, l2 in zip(f1_lists, f2_lists):
            l3.append(l1 + l2)
        return l3 # Return all the lines from both text files


def check_step_xrange(coordx):
    if coordx > 0.00 and coordx < 7.99:
        return "short"

def check_step_zrange(coordz):
    if coordz > 4.40 and coordz < 20.00:
        return "short"

# Ignore coordy for now
def grade_compass(coordx, coordy, coordz):
    if check_step_xrange(coordx) == "short" and check_step_zrange(coordz) == "short":
        compass_degree = "compass degree is short"
        return compass_degree


def main():
    file1 = "coordinates1.txt"
    file2 = "coordinates2.txt"
    args = merge_files(file1, file2)

    # List of instances
    compasslist = [Compass(args[i][0], args[i][1], args[i][2], args[i][3]) for i in range(len(args))]

    # I just pull the first instance
    print "\nThis is the object from the object list"
    print compasslist[0].coordx + ' ' + compasslist[0].coordy + ' ' + compasslist[0].coordz + ' ' + compasslist[0].coord_pos
    print grade_compass(compasslist[0].coordx, compasslist[0].coordy, compasslist[0].coordz)

    print "\nThis is the object manually given"
    h = Compass(2.02, -3.88, 15.25, 'P1')
    print h.coordx, h.coordy, h.coordz, h.coord_pos
    print grade_compass(h.coordx, h.coordy, h.coordz)
if __name__ == '__main__':
    main()

The first output return None. When given manually, it works.

output:

This is the object from the object list
2.02 -3.88 15.25 P1
None


This is the object manually given
2.02 -3.88 15.25 P1
compass degree is short

desired output:

This is the object from the object list
2.02 -3.88 15.25 P1
compass degree is short


This is the object manually given
2.02 -3.88 15.25 P1
compass degree is short

Solution

  • This is the difference between two approaches:

    Compass(args[i][0], args[i][1], args[i][2], args[i][3])
    
    Compass(2.02, -3.88, 15.25, 'P1')
    

    In the former, all arguments are string. So you need to cast them (or parse, if you cannot guarantee that the input is always correct:

    Compass(float(args[i][0]), float(args[i][1]), float(args[i][2]), args[i][3])