Loop thru the dictionary with tuples

[Igor Korot]

Hi, ALL,
I have a following data structure:

my_dict[(var1,var2,var3)] = None
my_dict[(var4,var5,var6)] = 'abc'

What I'm trying to do is this:

for (key,value) in my_dict:
#Do some stuff

but I'm getting an error "Too many values to unpack".

What am I doing wrong?

Thank you.

 

[Paul Rubin]

for (key,value) in my_dict:
#Do some stuff

but I'm getting an error "Too many values to unpack".

Use
for (key,value) in mydict.iteritems(): ...
otherwise you loop through just the keys, whicn in your dictionary
happens to be 3-tuples. So you try to unpack a 3-tuple to a 2-tuple
and get a too-many-values error.

 

[Tim Chase]

Use
for (key,value) in mydict.iteritems(): ...

You can even use

for ((k1,k2,k3), value) in mydict.iteritems():
...

if you need to unpack the key at the same time.

-tkc




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[Roy Smith]

for (key,value) in my_dict:
#Do some stuff

but I'm getting an error "Too many values to unpack".

Several people have already given you the right answer, so I'll just
suggest a general debugging technique. Break this down into the
smallest possible steps and print out the intermediate values. When you
write:

for (key,value) in my_dict:

two things are happening. One is that you're iterating over my_dict,
the other is that you're unpacking the iterated-over things. So break
those up into individual steps:

for thing in my_dict:
(key, value) = thing

and see what that gives you. Do you still get an error? If so, does it
occur on the "for" line or on the assignment line? Hint: in this case,
it will happen on the assignment line, so, your next step is to print
everything out and see what's going on:

for thing in my_dict:
print thing
(key, value) = thing

At this point, it should be obvious what's going on, but just in case
it's not, sometimes I find it useful to be even more verbose:

for thing in my_dict:
print type(thing), repr(thing)
(key, value) = thing

 

[Chris Angelico]

Hint: in this case,
it will happen on the assignment line, so, your next step is to print
everything out and see what's going on:

for thing in my_dict:
print thing
(key, value) = thing

Aside: I know that you (Roy) are still using Python 2, but the OP
could be on either branch. As a matter of safety, I'd put parens
around the print:

for thing in my_dict:
print(thing)
(key, value) = thing

That way, it works on either.

ChrisA