Function that depends on the row number

Question

In pandas, is it possible to reference the row number for a function. I am not talking about .iloc.

iloc takes a location i.e. a row number and returns a dataframe value.

I want to access the location number in the dataframe.

For instance, if the function is in the cell that is 3 rows down and 2 columns across, I want a way to return the integer 3. Not the entry that is in that location.

Thanks.

Could this be useful? http://stackoverflow.com/questions/18199288/getting-the-integer-index-of-a-pandas-dataframe-row-fulfilling-a-condition — Julien Spronck, Aug 02 '16 at 04:55
I think yuo need [`get_loc`](http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Index.get_loc.html) — jezrael, Aug 02 '16 at 04:58
There is another [question](http://stackoverflow.com/q/38441888/2901002) about it. — jezrael, Aug 02 '16 at 05:01

score 1 · Answer 1 · answered Aug 02 '16 at 05:48

Consider the dataframe df

df = pd.DataFrame([[1, 2], [3, 4]], ['a', 'b'], ['c', 'd'])

df

And the row row

row = df.ix['a']

row

c    1
d    2
Name: a, dtype: int64

There is nothing about this row that indicates that it was the first row of df. That information is essentially lost... sort of.

You can take @jezrael's advice and use get_loc

df.index.get_loc(row.name)

0

But this only works if your index is unique.

Your only other option is to track its position when you get it. The best way to do that is:

Use enumerate on df.iterrows()

for i, (idx, row) in enumerate(df.iterrows()):
    print "row position: {:>3d}\nindex value: {:>4s}".format(i, idx)
    print row, '\n'

row position:   0
index value:    a
c    1
d    2
Name: a, dtype: int64 

row position:   1
index value:    b
c    3
d    4
Name: b, dtype: int64

score 0 · Answer 2 · answered Aug 02 '16 at 13:25

0

Sorry I couldnt add a code sample but Im on my phone. piRSquared confirmed my fears when he said the info is lost. I guess ill have to do a loop everytime or add a column with numbers ( that will get scrambled if i sort them : / ).

Thanks everyone.

answered Aug 02 '16 at 13:25

Jared Gavin

21
1

Function that depends on the row number

2 Answers2