井民全觀點 (Jing's Perspective): [python, iloc, select] How to get the latest and the rest of column serials

a[start:stop] # items start through stop-1

a[start:] # items start through the rest of the array

a[:stop] # items from the beginning through stop-1

a[:] # a copy of the whole array

Reference

mydict = [{'a': 1, 'b': 2, 'c': 3, 'd': 4},

{'a': 100, 'b': 200, 'c': 300, 'd': 400}

{'a': 1000, 'b': 2000, 'c': 3000, 'd': 4000 }]

import pandas as pd

data = pd.DataFrame(mydict)

>>> data

a b c d

0 1 2 3 4

1 100 200 300 400

2 1000 2000 3000 4000

# Get the latest column serials

# Row selection: : <-- a copy whole row

# Col selection: -1 <-- choose the latest column

y = data.iloc[:, -1]

>>> y

0 4

1 400

2 4000

# Get the rest of the column serials

# Row selection: : <-- a copy whole row

# Col selection: :-1 <-- select whole column without the latest one

X = data.iloc[:,:-1]

>>> X

a b c

0 1 2 3

1 100 200 300

2 1000 2000 3000

2022年2月7日 星期一