CODEWITHSUNDEEP
python
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Reputation: 171

Some problem with dict function

I'm trying to convert a list to a dictionary by using the dict function.

inpu = input.split(",")
dic = dict(inpu)

The above code is trying to get a string and split it on ',' and afterwards I use the dict function to convert the list to a dictionary.

However, I get this error:

ValueError: dictionary update sequence element #0 has length 6; 2 is required

Can anybody help?

Upvotes: 14

Views: 33357

Answers (3)

gruntled
gruntled

Reputation: 2694

As listed on the Python Data structures Docs. The dict() constructor builds dictionaries directly from lists of key-value pairs stored as tuples.

so the inpu array must be of form ('key', 'value') at each position, for example

>>> dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])
{'sape': 4139, 'jack': 4098, 'guido': 4127}

your input array is probably greater than 2 in size

Upvotes: 3

mduvall
mduvall

Reputation: 1038

A dictionary is a key-value pair which is why it says length-2 lists are needed to match keys to values. You are splitting the input into a flat list, which is why Python is complaining in this case - it doesn't know what to specify as keys and what to specify as values.

Upvotes: 0

Zach Kelling
Zach Kelling

Reputation: 53819

dict expects an iterable of 2-element containers (like a list of tuples). You can't just pass a list of items, it doesn't know what's a key and what's a value.

You are trying to do this:

>>> range(10)
<<< [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> dict(range(10))
---------------------------------------------------------------------------
TypeError: cannot convert dictionary update sequence element #0 to a sequence

dict expects a list like this:

>>> zip(lowercase[:5], range(5))
<<< 
[('a', 0),
 ('b', 1),
 ('c', 2),
 ('d', 3),
 ('e', 4)]

The first element in the tuple becomes the key, the second becomes the value.

>>> dict(zip(lowercase[:5], range(5)))
<<< 
{'a': 0,
 'b': 1,
 'c': 2,
 'd': 3,
 'e': 4}

Upvotes: 21

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