在滚动平均值（python）中替换NaN

Question

我有一个数据集如下：

ts
Out[227]: 
       Sales
Month       
Jan     1808
Feb     1251
Mar     3023
Apr     4857
May     2506
Jun     2453
Jul     1180
Aug     4239
Sep     1759
Oct     2539
Nov     3923
Dec     2999

取窗口移动平均值= 2后，输出为：

shifted = ts.shift(0)

window = shifted.rolling(window=2)

means = window.mean()

print(means)
        Sales
Month        
Jan       NaN
Feb    1529.5
Mar    2137.0
Apr    3940.0
May    3681.5
Jun    2479.5
Jul    1816.5
Aug    2709.5
Sep    2999.0
Oct    2149.0
Nov    3231.0
Dec    3460.5

我希望NaN被其原始值替换。 可以吗？

Answer 1

尝试这个：

In [92]: ts.rolling(window=2, min_periods=1).mean()
Out[92]:
      Sales
Jan  1808.0
Feb  1529.5
Mar  2137.0
Apr  3940.0
May  3681.5
Jun  2479.5
Jul  1816.5
Aug  2709.5
Sep  2999.0
Oct  2149.0
Nov  3231.0
Dec  3461.0

Answer 2

采用：

df = df['Sales'].rolling(window=2).mean().fillna(df['Sales'])
print (df)
Jan    1808.0
Feb    1529.5
Mar    2137.0
Apr    3940.0
May    3681.5
Jun    2479.5
Jul    1816.5
Aug    2709.5
Sep    2999.0
Oct    2149.0
Nov    3231.0
Dec    3461.0
Name: Sales, dtype: float64

如果滚动n>2 ，则两种解决方案都存在差异：

df['Sales1'] = df['Sales'] * 2

df1 = df.rolling(window=3).mean().combine_first(df)
print (df1)
           Sales       Sales1
Jan  1808.000000  3616.000000
Feb  1251.000000  2502.000000 <-diff
Mar  2027.333333  4054.666667
Apr  3043.666667  6087.333333
May  3462.000000  6924.000000
Jun  3272.000000  6544.000000
Jul  2046.333333  4092.666667
Aug  2624.000000  5248.000000
Sep  2392.666667  4785.333333
Oct  2845.666667  5691.333333
Nov  2740.333333  5480.666667
Dec  3153.666667  6307.333333

df2 = df.rolling(window=3, min_periods=1).mean()
print (df2)
           Sales       Sales1
Jan  1808.000000  3616.000000
Feb  1529.500000  3059.000000 <-diff
Mar  2027.333333  4054.666667
Apr  3043.666667  6087.333333
May  3462.000000  6924.000000
Jun  3272.000000  6544.000000
Jul  2046.333333  4092.666667
Aug  2624.000000  5248.000000
Sep  2392.666667  4785.333333
Oct  2845.666667  5691.333333
Nov  2740.333333  5480.666667
Dec  3153.666667  6307.333333