Pandas操作まとめ【Python】

import pandas as pd 
import numpy as np 

n = [int(i) for i in range(0,5)]
l = np.array([[5*i+j for j in n] for i in n])
d = pd.DataFrame(data=l, index= [f"r{i}" for i in n], columns=[f"c{i}" for i in n])

#column
print(d["c2"])
#row
print(d[1:4])

>>>
r0     2
r1     7
r2    12
r3    17
r4    22
Name: c2, dtype: int64
    c0  c1  c2  c3  c4
r1   5   6   7   8   9
r2  10  11  12  13  14
r3  15  16  17  18  19

#extend row
d2 = pd.DataFrame(data=[[i**2 for i in n]],index = ["r5"],columns=[f"c{i}" for i in n])

#append
d = d.append(d2,ignore_index = False)
print(d)
>>>
    c0  c1  c2  c3  c4
r0   0   1   2   3   4
r1   5   6   7   8   9
r2  10  11  12  13  14
r3  15  16  17  18  19
r4  20  21  22  23  24
r5   0   1   4   9  16

#extend col
d["c5"] = [i for i in range(len(d.index))]
print(d)
>>>
   c0  c1  c2  c3  c4  c5
r0   0   1   2   3   4   0
r1   5   6   7   8   9   1
r2  10  11  12  13  14   2
r3  15  16  17  18  19   3
r4  20  21  22  23  24   4
r5   0   1   4   9  16   5