import numpy as np
import pandas as pd
import statsmodels.api as sm

def smooth(y:pd.Series,frac):
    y             = y.dropna()
    index         = y.index
    x             = np.arange(len(y))
    lowess_result = sm.nonparametric.lowess(y, x, frac=frac) 
    return pd.Series(lowess_result[:, 1], index=index)