Do operations on columns in a Dataframe loop

The problem is that you are using a variable that has not yet been assigned:

for i,column in enumerate(df[column]):

column in the enumerate (df [column]) segment is not defined.

I should try something similar to this:

def calculateAllEMA(values_array):
    df = pd.DataFrame(values_array, columns=['BTC', 'ETH', 'DASH'])
    column_by_search = "BTC" # Según el nombre de la columna en 'columns'
    for i,column in enumerate(df[column_by_search]):

It seems to me that what you need, if you want to iterate each column, is something like this:

def calculateAllEMA(self,values_array):
    columns = ['BTC', 'ETH', 'DASH']
    df = pd.DataFrame(values_array, columns=columns)
    for i, column in enumerate(columns):
        ema=[]
        for j in range(0, len(df[column])-24):
            EMA_yesterday = df[column].iloc[1+j:22+j].mean()
            k = float(2)/(22+1)
            ema.append(df[column].iloc[23 + j]*k+EMA_yesterday*(1-k))
        mean_exp[i] = ema[-1]
    return mean_exp

I'm not sure if df[column] is correct since I do not know much about the library, but it makes sense.

Keep in mind that in the second loop I'm using j to not interfere with the i of your first loop.

Pandas has its own iterators, if you want to iterate through columns and at the same time collect the index of each column, it would be like this:

import pandas as pd

df = pd.DataFrame(data = values, columns = ['BTC', 'ETH', 'DASH'])

for idx,columna in enumerate(df):

print(idx, columna)

Exit:

0 BTC
1 ETH
2 DASH

If you want to go through rows:

for fila in df.iterrows():

    print(fila)

Exit:

(0, BTC     3554.05
ETH      299.44
DASH     198.51
Name: 0, dtype: float64)
(1, BTC     3554.05
ETH      299.46
DASH     198.51
Name: 1, dtype: float64)
(2, BTC     3554.05
ETH      299.55
DASH     198.54
Name: 2, dtype: float64)

...

So your function would look like this:

def calculateAllEMA(self,values_array):

    df = pd.DataFrame(values_array, columns=['BTC', 'ETH', 'DASH'])


    for idx,column in enumerate(df):

        ema=[]

        for i in range(0, len(df)-24):

            EMA_yesterday = column.iloc[1+i:22+i].mean()

            k = float(2)/(22+1)

            ema.append(column.iloc[23 + i]*k+EMA_yesterday*(1-k))

        mean_exp[i] = ema[-1]

    return mean_exp

I hope it helps.