Add value in Pandas Dataframe from Numpy Array

Question

I have a data frame which has a (3,1) df-shape like this:-

My Dataframe:

 KDB 0 2 1 7 2 9

And I have a NumPy array that looks like this

My Numpy Array:

[[40],[50],[60]]

I want to append the value of a specific index in the array to my data frame. Let's say I want to add "60" to my data frame. So, I want my data frame to look like this.

My New Dataframe:

 KDB 0 2 1 7 2 9 3 60

I wrote a code, but it didn't work.

new_df = my_df.append(pd.Series(my_array[2][0]), ignore_index=True)

Python throws this error "non-broadcastable output operand with shape (3,1) doesn't match the broadcast shape (3,2)"

Can someone please help me understand what am I doing wrong?

Thank you so much!

Answer 1

Your code did not cause any error, but my DataFrame has:

• 0, 1, 2 as the index column,
• the only data columns is KDB .

But the result is wrong, as it contains 2 columns.

To get the proper result, use the following code:

my_df.append(pd.Series(my_array[2], index=['KDB']), ignore_index=True)

The trick is to specify the column name as the index in the temporary Series , so the value of interest is added to the right column.