How to Append data in While loop into Empty DataFrame

Question

I have dataframe which has 5 columns.

Df = pd.DataFrame(columns=['userId','movieId','rating','timestamp','genres'])

I have this function

def Main():

    flag = 0
    while(flag <=99):
        data1 = pickRandomMovies()
        data2 = usersToMovies(data1)
        if len(data2) < 6:
            data2 = data1
        else:
            flag +=1
            data3 = commonUsers(data2)
            #append all values of data3 here to new dataframe
            df_new.append(data3)

            findingRatings(data3)

>>data3
userId  movieId  rating   timestamp                      genres
 27       60      3.0     962685387         Adventure|Children|Fantasy
 103      60      4.0     1431968436        Adventure|Children|Fantasy
 160      60      2.0     971619579         Adventure|Children|Fantasy
 27      1210     4.0     962684909         Action|Adventure|Sci-Fi
 103     1210     3.5     1431957028        Action|Adventure|Sci-Fi
 160     1210     5.0     971113953         Action|Adventure|Sci-Fi

i want to append all values of data3 into new dataframe in every iteration.

you can initialize a new dataframe e.g. df_new = pd.DataFrame(columns=['whatever']) and then you can use df_new.append(data3). If the collumns are the same then this will be okay. — geoph9
– geoph9, Commented Dec 3, 2019 at 8:44
How does the data in data3 looks like? Could you print out data3 so its easier to see? — Jan33
– Jan33, Commented Dec 3, 2019 at 8:49
can you share the code you have tried for which you got empty dataframe — ArunJose
– ArunJose, Commented Dec 3, 2019 at 9:12

ArunJose · Accepted Answer · 2019-12-03 09:16:25Z

1

change your code to

def Main():

    flag = 0
    while(flag <=99):
        data1 = pickRandomMovies()
        data2 = usersToMovies(data1)
        if len(data2) < 6:
            data2 = data1
        else:
            flag +=1
            data3 = commonUsers(data2)
            #append all values of data3 here to new dataframe
            df_new=df_new.append(data3)

            findingRatings(data3)

df_new.append(data3) only appends the value it does not assign the value it should be done explicitly by df_new=df_new.append(data3)

answered Dec 3, 2019 at 9:16

ArunJose

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