Question

I am currently working on python programming.

class A:
    def LoadPosition(self):
        FILE = open('a.txt', "r+")

        i = 0
        for node in self.nodes:
            line = FILE.readline()
            if i == 0:
                scaling_factor == float(line)
                i += 1
            else:
                tmpn, tmpx, tmpy, tmpa = line.split('\t')
                node.id = tmpn
                node.coordinate_x = float(tmpx)
                node.coordinate_y = float(tmpy)
                node.area = int(tmpa)
        FILE.close()

It was fine before, but all of sudden, it shows the NameError message. Please help me out.

Thanks in advance.

Answer 1

You’re mixing spaces and tabs in strange ways, which is probably confusing Python. Here’s what I get when I copy-and-paste your code from the edit window:

In [2]: for line in s.splitlines():
   ...:     print repr(line)
   ...:     
''
'    class A:'
'    \tdef LoadPosition(self):'
'\t        FILE = open(\'a.txt\', "r+")'
'    \t'
'\t\t    i = 0'
'    \t    for node in self.nodes:'
'    \t    \tline = FILE.readline()'
'    \t    \tif i == 0:'
'    \t    \t\tscaling_factor == float(line)'
'    \t    \t\ti += 1'
'    \t    \telse:'
"    \t    \t\ttmpn, tmpx, tmpy, tmpa = line.split('\t')"
'\t       \t     \tnode.id = tmpn'
'   \t\t         \tnode.coordinate_x = float(tmpx)'
'   \t\t         \tnode.coordinate_y = float(tmpy)'
'   \t\t     \t    node.area = int(tmpa)'
'\t\t    FILE.close()'

[Note that if someone copies code from the posted question and not the raw edit window, this might not happen — at least sometimes it’s suppressed seeing the original tabs for me — and so people who try your code might not have any problems.]

Step #1: run your code using python -tt yourfilenamehere.py to confirm that it’s a tab error.

Step #2: switch to using four-space tabs everywhere.