1 diff()是将原来的数据减去移动后的数据.
在numpy和pandas中都能调用.
pandas的调用方法：
import pandas as pd
df = pd.DataFrame( {'a':[1,2,3,4,5],
'b':[6,7,8,9,10],
'c':[11,12,13,14,15]})
print(df)
# axis=0或index表示上下移动， periods表示移动的次数，为正时向下移，为负时向上移动。
print(df.diff( periods=1, axis='index'))
print(df.diff( periods=-1, axis=0))
# axis=1或columns表示左右移动，periods表示移动的次数，为正时向右移，为负时向左移动。
print(df.diff( periods=1, axis='columns'))
print(df.diff( periods=-1, axis=1))
# a b c
# 0 1 6 11
# 1 2 7 12
# 2 3 8 13
# 3 4 9 14
# 4 5 10 15
# a b c
# 0 NaN NaN NaN
# 1 1.0 1.0 1.0
# 2 1.0 1.0 1.0
# 3 1.0 1.0 1.0
# 4 1.0 1.0 1.0
# a b c
# 0 -1.0 -1.0 -1.0
# 1 -1.0 -1.0 -1.0
# 2 -1.0 -1.0 -1.0
# 3 -1.0 -1.0 -1.0
# 4 NaN NaN NaN
# a b c
# 0 NaN 5.0 5.0
# 1 NaN 5.0 5.0
# 2 NaN 5.0 5.0
# 3 NaN 5.0 5.0
# 4 NaN 5.0 5.0
# a b c
# 0 -5.0 -5.0 NaN
# 1 -5.0 -5.0 NaN
# 2 -5.0 -5.0 NaN
# 3 -5.0 -5.0 NaN
# 4 -5.0 -5.0 NaN
numpy中的调用方法：
参考：https://blog.csdn.net/qq_32618817/article/details/80653841