Python: how to remove a value from a dict if it exactly matches the key?

Question

Being that the key has multiple values and I want to remove the one that is the same as the key itself? That is, I have a dictionary jumps:

jumps = {'I6': ['H6', 'I6', 'I5'], 'T8' : ['T6', 'S6', 'T8']}

And I want to delete the value 'I6' from the 'I6' key and also 'T8' from the 'T8' key. How could I do this? I'm getting mixed up in parsing the strings versus the values.

Answer 1

You can use a one-liner with both dictionary comprehension and list comprehension:

result = {k:[vi for vi in v if k != vi] for k,v in jumps.items()}

This results in:

>>> {k:[vi for vi in v if k != vi] for k,v in jumps.items()}
{'T8': ['T6', 'S6'], 'I6': ['H6', 'I5']}

Note that you will remove all elements from the lists that are equal to the key. Furthermore the remove process is done for all keys.

The code works as follows: we iterate over every key-value pair k,v in the jumps dictionary. Then for every such pair, we construct a key in the resulting dictionary, and associate [vi for vi in v if k != vi] with it. That is a list comprehension where we filter out all values of v that are equal to k. So only the vis remain (in that order) that are k != vi.