appending list to a dataframe

Question

I'm not understanding the behavior of appending data to a dataframe.

what i want to do is append a list with two values like this:

temp_arr
[Timestamp('2018-01-01 00:00:00', freq='D'), 0]

to a dataframe with two columns. However, its adding two rows, not one row with two columns:

df_final = df_final.append(pd.DataFrame(temp_arr),ignore_index=True)

produces something like this:

df_final.head()
0
0   2018-01-01 00:00:00
1   0
2   2018-01-02 00:00:00
3   0
4   2018-01-03 00:00:00

instead of something like this

df_final.head()

col1  col2
0     2018-01-01 00:00:00

Try, df_final = pd.concat([df_final, pd.DataFrame(temp_arr)], ignore_index=True) — cs95
– cs95, Commented Mar 19, 2018 at 16:40
@coldspeed nope, got the same results - does it have something to do with the fact I'm using a timestamp? — Derek Krantz
– Derek Krantz, Commented Mar 19, 2018 at 16:46

Vaishali · Accepted Answer · 2018-03-19 16:45:41Z

1

Try

df = pd.DataFrame(columns = ['col1', 'col2'])
temp_arr = [pd.Timestamp('2018-01-01 00:00:00', freq='D'), 0]
df.append(pd.Series(temp_arr, index = ['col2', 'col1']),ignore_index=True)

You get

    col1    col2
0   0   2018-01-01

answered Mar 19, 2018 at 16:45

Vaishali

38.5k5 gold badges62 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Derek Krantz Over a year ago

this doesn't work. running your code for me produces an empty dataframe. Also, pd.Series produces one column - I want to essentially two columns to a dataframe

Vaishali Over a year ago

Can you share more details, how are you creating the empty data frame? Because it works for me

Derek Krantz Over a year ago

my error it works now. Can you explain the behavior of the Series in your code? i thought index sets an index for rows not columns as in this case

Vaishali Over a year ago

When you append a data frame to another data frame, it maps the column names. Whereas when you append a series to the dataframe, it maps the indices of the series with that of columns of the dataframe

Collectives™ on Stack Overflow

appending list to a dataframe

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related