Negative indexing/selecting working and not working

[deanhystad]

Looking at your code, perc is Pandas series, not a list. Indexing for a series does not work like indexing in a list. Indexing for a series works more like indexing in a dictionary. The index value is a key, not a position. The error message would be

Error:
KeyError: -2

This error will occur if you have a question that contains no "Strongly Disagree" type.

But I don't get an error when I run your code. I get this.

Output:
      question                        type  value  percentage  percentage_end  percentage_start
0   Question 1           Strongly disagree     24    0.746501      -18.382582        -19.129082
1   Question 1                    Disagree    294    9.144635       -9.237947        -18.382582
2   Question 1  Neither agree nor disagree    594   18.475894        9.237947         -9.237947
3   Question 1                       Agree   1927   59.937792       69.175739          9.237947
4   Question 1              Strongly agree    376   11.695179       80.870918         69.175739
5   Question 2           Strongly disagree      2    9.090909       -9.090909        -18.181818
6   Question 2                    Disagree      2    9.090909        0.000000         -9.090909
7   Question 2  Neither agree nor disagree      0    0.000000        0.000000          0.000000
8   Question 2                       Agree      7   31.818182       31.818182          0.000000
9   Question 2              Strongly agree     11   50.000000       81.818182         31.818182
10  Question 3           Strongly disagree      2   20.000000      -10.000000        -30.000000
11  Question 3                    Disagree      0    0.000000      -10.000000        -10.000000
12  Question 3  Neither agree nor disagree      2   20.000000       10.000000        -10.000000
13  Question 3                       Agree      4   40.000000       50.000000         10.000000
14  Question 3              Strongly agree      2   20.000000       70.000000         50.000000
15  Question 4           Strongly disagree      0    0.000000      -15.625000        -15.625000
16  Question 4                    Disagree      2   12.500000       -3.125000        -15.625000
17  Question 4  Neither agree nor disagree      1    6.250000        3.125000         -3.125000
18  Question 4                       Agree      7   43.750000       46.875000          3.125000
19  Question 4              Strongly agree      6   37.500000       84.375000         46.875000
20  Question 5           Strongly disagree      0    0.000000      -10.416667        -10.416667
21  Question 5                    Disagree      1    4.166667       -6.250000        -10.416667
22  Question 5  Neither agree nor disagree      3   12.500000        6.250000         -6.250000
23  Question 5                       Agree     16   66.666667       72.916667          6.250000
24  Question 5              Strongly agree      4   16.666667       89.583333         72.916667
25  Question 6           Strongly disagree      1    6.250000      -12.500000        -18.750000
26  Question 6                    Disagree      1    6.250000       -6.250000        -12.500000
27  Question 6  Neither agree nor disagree      2   12.500000        6.250000         -6.250000
28  Question 6                       Agree      9   56.250000       62.500000          6.250000
29  Question 6              Strongly agree      3   18.750000       81.250000         62.500000
30  Question 7           Strongly disagree      0    0.000000      -10.000000        -10.000000
31  Question 7                    Disagree      0    0.000000      -10.000000        -10.000000
32  Question 7  Neither agree nor disagree      1   20.000000       10.000000        -10.000000
33  Question 7                       Agree      4   80.000000       90.000000         10.000000
34  Question 7              Strongly agree      0    0.000000       90.000000         90.000000
35  Question 8           Strongly disagree      0    0.000000        0.000000          0.000000
36  Question 8                    Disagree      0    0.000000        0.000000          0.000000
37  Question 8  Neither agree nor disagree      0    0.000000        0.000000          0.000000
38  Question 8                       Agree      0    0.000000        0.000000          0.000000
39  Question 8              Strongly agree      2  100.000000      100.000000          0.000000

Are you sure the error you are getting is associated with the code in your post?

In the future please post the entire error message, including the trace.