columnas de desplazamiento de pandas hasta el valor
#We create a shift down method so that we can have all the preious summed values in the bottom index and hence
#deleting them would be easy
def shift_down(data):
i=0
while(i<len(data.columns)):
while(pd.isnull(data.iloc[len(data.index)-1,i])==True):
data.iloc[:,i] = data.iloc[:, i].shift(1)
i+=1
return data
M.U