基本用法
import pandas as pd
import numpy as np
df = pd.Dataframe(np.arange(12).reshape(3, 4), index=pd.date_range(start='20170101', periods=3),columns=['A','B','C','D'])
df
| A | B | C | D |
|---|
| 2017-01-01 | 0 | 1 | 2 | 3 |
|---|
| 2017-01-02 | 4 | 5 | 6 | 7 |
|---|
| 2017-01-03 | 8 | 9 | 10 | 11 |
|---|
1、后一项减去前一项的差，记录在后一项位置
df1 = df.diff()
df1
| A | B | C | D |
|---|
| 2017-01-01 | NaN | NaN | NaN | NaN |
|---|
| 2017-01-02 | 4.0 | 4.0 | 4.0 | 4.0 |
|---|
| 2017-01-03 | 4.0 | 4.0 | 4.0 | 4.0 |
|---|
df1.fillna(0)
| A | B | C | D |
|---|
| 2017-01-01 | 0.0 | 0.0 | 0.0 | 0.0 |
|---|
| 2017-01-02 | 4.0 | 4.0 | 4.0 | 4.0 |
|---|
| 2017-01-03 | 4.0 | 4.0 | 4.0 | 4.0 |
|---|
2、右边减去左边的差值，记录在右边的位置
df2 = df.diff(axis=1)
df2
| A | B | C | D |
|---|
| 2017-01-01 | NaN | 1.0 | 1.0 | 1.0 |
|---|
| 2017-01-02 | NaN | 1.0 | 1.0 | 1.0 |
|---|
| 2017-01-03 | NaN | 1.0 | 1.0 | 1.0 |
|---|
df2.fillna(0)
| A | B | C | D |
|---|
| 2017-01-01 | 0.0 | 1.0 | 1.0 | 1.0 |
|---|
| 2017-01-02 | 0.0 | 1.0 | 1.0 | 1.0 |
|---|
| 2017-01-03 | 0.0 | 1.0 | 1.0 | 1.0 |
|---|
