python KeyError: even when the column name exists

Question

I am attempting to index a pandas dataframe by a column in the dataframe and get KeyError. For example, the dataframe has rows indexed on general ledger account name ('Cash','Securities', etc) and the columns are indexed by the time period ('Q1_2018', 'Q2_2018', etc.). These values are confirmed when I use df.index and df.columns. However, when i run df.loc['Cash','Q1_2018'], it returns the following KeyError: 'Q1_2018'. Any thoughts on why this would occur.

            Q1_2018     Q2_2018     Q3_2018
Cash        2000000     2000100     1900000
Securites   3000000     2999900     2910000

`iloc` takes integers as input. use `df.loc['Cash', 'Q1_2018']`. — Quang Hoang, Sep 17 '19 at 15:11
Maybe you have Q1_2018 with some spaces around it in the column. — kantal, Sep 17 '19 at 16:26
Thank you for the suggestion. This is not the issue as I have double-checked. I get the error message no matter which quarter I try to index, and they are all spelled correctly with no known extra spaces. — carrie3zz, Sep 17 '19 at 17:47
@carrie3zz Please, show the code that creates the data frame. — kantal, Sep 17 '19 at 18:12

score 0 · Answer 1 · answered Sep 17 '19 at 15:14

0

I see that you have used iloc with labels of your dataframe. Do note that since you are using labels, you should be trying with loc instead.

Here are some pages that might interest you on how both methods work:

https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.loc.html https://pandas.pydata.org/pandas-docs/version/0.25/reference/api/pandas.DataFrame.iloc.html

loc vs iloc How are iloc, ix and loc different?

answered Sep 17 '19 at 15:14

cyneo

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I mistyped in the original post. I am using loc not iloc. – carrie3zz Sep 17 '19 at 15:19
In that case, may i suggest you edit your post so as not to confuse others? – cyneo Sep 17 '19 at 15:26
I tried to edit initially and could not figure out how. Now it is updated. Thanks. – carrie3zz Sep 17 '19 at 16:04
Hey, did you find a solution to this? Currently pulling my hair out at the same issue – Zizi96 Nov 14 '20 at 14:32

python KeyError: even when the column name exists

1 Answers1