比较 DataFrame 中的行

Question

I have a DataFrame suppose say df .

import pandas as pd

data_dic = {
    "a": [0,0,1,2],
    "b": [0,3,4,5],
    "c": [6,7,8,9]
}
df = pd.DataFrame(data_dic)

It will look like:

   a  b  c
0  0  0  6
1  0  3  7
2  1  4  8
3  2  5  9

Now i want to compare row[0] with row[1] for column a and post the greater value or some remark in a new column, say d .

I have tried using:

for i in range(len(df):
   if (df.iloc[a][i] > df.iloc[a][i+1]):
      df[d] = "Post the greater number"

I am getting an error:

IndexError: single positional indexer is out-of-bounds

Can some one help me?

Answer 1

The problem is that you when i is at the last index, i+1 will be out of bounds.

I think you might want to write:

for i in range(len(df) - 1):
  if (df.iloc[a][i] > df.iloc[a][i+1]):
    df[d] = "Post the greater number"