[파이썬]Pandas 행,열 생성 및 수정하기

행, 열 생성 / 수정¶

열 생성¶

In [39]:

import pandas as pd
people = [
    {'name': 'Kim', 'midterm': 90, 'final': 85},
    {'name': 'Lee', 'midterm': 80, 'final': 75},
    {'name': 'Choi', 'midterm': 65, 'final':100}
]
df = pd.DataFrame(people)

In [40]:

df

Out[40]:

	name	midterm	final
0	Kim	90	85
1	Lee	80	75
2	Choi	65	100

In [41]:

df['total'] = df['midterm'] + df['final']
df

Out[41]:

	name	midterm	final	total
0	Kim	90	85	175
1	Lee	80	75	155
2	Choi	65	100	165

In [43]:

df['avg'] = df['total'] / 2
df

Out[43]:

	name	midterm	final	total	avg
0	Kim	90	85	175	87.5
1	Lee	80	75	155	77.5
2	Choi	65	100	165	82.5

In [54]:

grades = []

for row in df['avg']:
    if row >85:
        grades.append('A')
    elif row > 80:
        grades.append('B')
    else:
        grades.append('F')
        
df['grade'] = grades
df

Out[54]:

	name	midterm	final	total	avg	grade
0	Kim	90	85	175	87.5	A
1	Lee	80	75	155	77.5	F
2	Choi	65	100	165	82.5	B

함수와 apply를 이용하기¶

In [55]:

def pass_or_fail(row):
    if row != 'F':
        return 'Pass'
    else:
        return 'Fail'

In [56]:

df.grade = df.grade.apply(pass_or_fail)
df

Out[56]:

	name	midterm	final	total	avg	grade
0	Kim	90	85	175	87.5	Pass
1	Lee	80	75	155	77.5	Fail
2	Choi	65	100	165	82.5	Pass

행 생성하기¶

In [59]:

df2 = pd.DataFrame([
    ['Park', 88, 90]],
    columns=['name', 'midterm', 'final']
)
df2

Out[59]:

	name	midterm	final
0	Park	88	90

In [60]:

df.append(df2, ignore_index=True)

Out[60]:

	name	midterm	final	total	avg	grade
0	Kim	90	85	175.0	87.5	Pass
1	Lee	80	75	155.0	77.5	Fail
2	Choi	65	100	165.0	82.5	Pass
3	Park	88	90	NaN	NaN	NaN

In [ ]: