CODEWITHSUNDEEP
pythonpandasdataframe
Mainland
Mainland

Reputation: 4564

Python iloc giving indexError: single positional indexer is out-of-bounds in simple for loop

I have dataframe as given below:

df = 
          0
1      0.993995
2      1.111068
3      1.760940
.
.
.
49    40.253574
50    40.664486
51    41.083962

I am iterating through each row and print each element. My code is given below:

for idx,row in df.iterrows():
    print(df[0].iloc[idx])

Present output: 

1.111068
1.76094
2.691832
.
.
40.664486
41.083962
Traceback (most recent call last):

  File "<ipython-input-46-80539a9081e5>", line 2, in <module>
    print(darkdf[0].iloc[idx])

  File "C:\Users\MM\Anaconda3\lib\site-packages\pandas\core\indexing.py", line 1500, in __getitem__
    return self._getitem_axis(maybe_callable, axis=axis)

  File "C:\Users\MM\Anaconda3\lib\site-packages\pandas\core\indexing.py", line 2230, in _getitem_axis
    self._validate_integer(key, axis)

  File "C:\Users\MM\Anaconda3\lib\site-packages\pandas\core\indexing.py", line 2139, in _validate_integer
    raise IndexError("single positional indexer is out-of-bounds")

IndexError: single positional indexer is out-of-bounds

Why this simple function is giving error. Someone could help me to understand what the error is saying?

Upvotes: 5

Views: 16316

Answers (2)

jezrael
jezrael

Reputation: 862501

First correct way for select is use DataFrame.loc:

print (df)
          0
1  0.993995
2  1.111068
3  1.760940

for idx,row in df.iterrows():
    print(df.loc[idx, 0])
0.9939950000000001
1.111068
1.7609400000000002

Problem in your solution:

If use Series.iloc function it select by position, not by labels.

So you want select 4.th row by selecting:

df[0].iloc[3]

but there is not 4.th (python counts from 0, so for select 4.th row need 3) row so raised error.

If use:

df[0].loc[3]

it working like you expected, because selecting index 3 (not position 4 which not exist) and column 0, but better is use:

df.loc[idx, 0]

because evaluation order matters.

Upvotes: 4

KJ Nam
KJ Nam

Reputation: 106

You may want to use loc instead of iloc. iloc uses the zero-based row number, not indices. Your code is passing the indices, which go over the range of the zero-based row numbers, hence out-of-bounds.

Upvotes: 3

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