Filtering a Dictionary with mutiple keys and multiple values per key

Question

I have a question regarding how to filter a dictionary using a loop.

Here is an example of the dictionary:

d = {'beta': ['ABC', '1', '5', '10', '15'],
     'lambda': ['DEF', '3', '30', '22.2', '150'],
     'omega': ['RST','15', '54.4', '150', '75']
}

How do I filter the dictionary to remove keys if the 3rd value in each key is < 100? In other words, after the if function, only omega should be left in the dictionary.
I tried:

for k, v in d.iteritems(): 
    r = float((d[key][2]))
    if r < float(100):
        del d[k]

But it did not work. Any thoughts? New to python programming here.

The new dictionary should just leave the omega key since 150 is greater than 100.

the third value, so basically because the third value is above 100, the dictionary should only hold the Omega key but maintain all omega key values. Simply, my loop should remove the beta and lambda keys. — Deuce525, Sep 01 '16 at 17:01

JClarke · Accepted Answer · 2016-09-01T19:28:51.937

0

def cast_values(v):
    try:
        return float(v)
    except ValueError:
        return v

new_d = {k:[ cast_values(i) for i in v ] for k,v in d.items() if float(v[3]) > 100}

Results:

new_d = {'omega': ['RST', 15, 54.4, 150, 75]}

edited Sep 01 '16 at 19:28

answered Sep 01 '16 at 16:48

JClarke

788
1
9
22

Jclarke, i think that works but in my actual program where i tried to apply this, it gives me a syntax error of cannot convert string to float. I think its treating the values in the key as strings and not values. Any idea on how to fix that? – Deuce525 Sep 01 '16 at 17:08
Unless you're passing the key by mistake instead of the value then you're going to get that error. I tested code with the information you gave and don't get that issue. Make sure you're passing the proper values in `float()` part of the code. – JClarke Sep 01 '16 at 17:12
`ValueError: could not convert string to float:` will happen if it is passed something like `float('word')` but will properly cast `float('100')` – JClarke Sep 01 '16 at 17:20
so looking again, i'm getting the error cause the values in my dict are shown as '100' , how do i remove the ' ' from the number? i could manually do it in my example, but in my actual program i have thousands of numbers. – Deuce525 Sep 01 '16 at 17:26
Is it happening in the new dict that is created ? – JClarke Sep 01 '16 at 17:32
my original dictionary has the ' ', i forgot to add that into the example so when i run your syntax, it gives me that cannot convert string to float error – Deuce525 Sep 01 '16 at 17:46
I made an update! Next time post your data in the state it was in when you got your error(s) – JClarke Sep 01 '16 at 17:46
That works! thank you! I do have one last question, if i do have a string in my key, not just values to convert, is there a way to keep the string a string? See updated question above. Thanks! – Deuce525 Sep 01 '16 at 19:04
It worked! after a few modifications to another part of my code! – Deuce525 Sep 02 '16 at 02:02

Filtering a Dictionary with mutiple keys and multiple values per key

1 Answers1