如何使用多个数据集运行1个函数？

Question

Assuming I got 20 set of data which I read it as df1,df2,df3,df4...df20. (Any other smart way to read or store dataframe?)

my function be like:

def CalculateEMA(x,window):    
    sma = x.rolling(window, min_periods=window).mean()[:window]
    rest = x[window:]
    EMA_window=(pd.concat([sma, rest]).ewm(span=window,adjust=False).mean()).sum())

    return EMA_window

And I wish to return a EMA for all 20 data frame and store as X . So my final output will be X = [x1,x2,x3,x,x,x,x,x...x20]. Where x1 is the Sum of EMA fucntion for df1 and x2 is second dataset df2 and so on.

Answer 1

You can loop throughout your dataframes if you stock them in a list :

X=list()
list_df = [df1,df2,...,df20]
for df in list_df:
    X.append(CalculateEMA(df,window))

Answer 2

to read all the csv files in a folder you can make use of os function

    import os
    path_to_dir='<your path>'
    filenames = os.listdir(path_to_dir)
    csvs=[f for f in filenames if f.endswith('csv')]
    out=[]
    for path in csvs:
        df=pd.read_csv(path)
        out.append(CalculateEMA(df,window))