读取.obj文件和分割线

Question

I made a simple code to read a .obj file that looks like this

g cube

v  0.0  0.0  0.0
v  0.0  0.0  1.0
v  0.0  1.0  0.0
v  0.0  1.0  1.0
v  1.0  0.0  0.0
v  1.0  0.0  1.0
v  1.0  1.0  0.0
v  1.0  1.0  1.0

f  1//2  7//2  5//2
f  1//2  3//2  7//2 
f  1//6  4//6  3//6 
f  1//6  2//6  4//6 
f  3//3  8//3  7//3 
f  3//3  4//3  8//3 
f  5//5  7//5  8//5 
f  5//5  8//5  6//5 
f  1//4  5//4  6//4 
f  1//4  6//4  2//4 
f  2//1  6//1  8//1 
f  2//1  8//1  4//1 

And the python code looks like this

class objeto():
def __init__(self, obj = None):
    if obj:
        self.cargar_obj(obj)

def cargar_obj(self, archivo):
    with open(archivo, 'r') as obj:
        datos = obj.read()

    lineas = datos.splitlines()
    self.vertices = []
    self.superficies = []

    for linea in lineas:
        elem = linea.split()
        if elem:
            if elem[0] == 'v':
                v = vertice(float(elem[1]), float(elem[2]), float(elem[3]))
                self.vertices.append(v)
            elif elem[0] == 'f':
                vs = []
                for i in range(1, len(elem)):
                    vs.append(self.vertices[int(elem[i].split('/'))])

                f = cara(vs)
                self.superficies.append(f)
            else:
                pass

The problem appears to be this line:

vs.append(self.vertices[int(elem[i].split('/'))])

because when I try to run the code, the followed TypeError appears

int() argument must be a string, a bytes-like object or a number, not 'list'

I'm a newbie in Python, so I don't seem to get around this error, can somebody give me some advice? Thanks.

I'm using Python 3.x, and ipython to run .py files

Answer 1

Recreate your case with one line:

In [435]: line='f  1//2  7//2  5//2'
In [436]: elem = line.split()
In [437]: elem
Out[437]: ['f', '1//2', '7//2', '5//2']
In [438]: elem[0]
Out[438]: 'f'

split on / behaves as I expect:

In [439]: for i in range(1,len(elem)):
     ...:    print(elem[i].split('/'))
     ...:    
['1', '', '2']
['7', '', '2']
['5', '', '2']

Your code has problems applying int to that list of strings:

In [440]: for i in range(1,len(elem)):
     ...:    print(int(elem[i].split('/')))
     ...
TypeError: int() argument must be a string, a bytes-like object or a number, not 'list'

So we need to apply int() to the individual strings, not the list. But now the empty string is giving me problems.

In [441]: for i in range(1,len(elem)):
     ...:    print([int(e) for e in elem[i].split('/')])
     ...:        
ValueError: invalid literal for int() with base 10: ''

The rest is left as an exercise for the reader.

Couldn't resist:

[int(e) for e in elem[i].replace('//','/').split('/')]
[int(e) for e in elem[i].split('/') if e]

Answer 2

The error message is pretty clear: you are passing int a list (the result of calling split ); maybe you only meant to call it with one of the elements of that list.