Changing variable names with Python for loops

Question

Hi, I was just wondering if anyone knew of a way to change variable names based off of a for loop for something like this:

for i in range(3)
     group+i=self.getGroup(selected, header+i)

so that the names of the variables change to accomodate the data. Thanks!

~Sam

Answer 1

It looks like you want to use a list instead:

group=[]
for i in range(3):
     group[i]=self.getGroup(selected, header+i)

Answer 2

You probably want a dict instead of separate variables. For example

d = {}
for i in range(3):
    d["group" + str(i)] = self.getGroup(selected, header+i)

If you insist on actually modifying local variables, you could use the locals function:

for i in range(3):
    locals()["group"+str(i)] = self.getGroup(selected, header+i)

On the other hand, if what you actually want is to modify instance variables of the class you're in, then you can use the setattr function

for i in group(3):
    setattr(self, "group"+str(i), self.getGroup(selected, header+i)

And of course, I'm assuming with all of these examples that you don't just want a list:

groups = [self.getGroup(i,header+i) for i in range(3)]

Answer 3

You could access your class's __dict__ attribute:

for i in range(3)
     self.__dict__['group%d' % i]=self.getGroup(selected, header+i)

But why can't you just use an array named group?

Answer 4

Use a list.

groups = [0]*3
for i in xrange(3):
    groups[i] = self.getGroup(selected, header + i)

or more "Pythonically":

groups = [self.getGroup(selected, header + i) for i in xrange(3)]

For what it's worth, you could try to create variables the "wrong" way, i.e. by modifying the dictionary which holds their values:

l = locals()
for i in xrange(3):
    l['group' + str(i)] = self.getGroup(selected, header + i)

but that's really bad form, and possibly not even guaranteed to work.