How do combine multiple columns into one column such that column 2 starts at the end of column 1 usi-CodePudding

I'm using pandas and I have a data frame with multiple columns like this:

Col1 CoL2 Col3
A      E    I
B      F    J
C      G    K
Nan    H    L
D      NaN

and so on..

How can I combine these columns into one so that it becomes:

New Col
A
B
C
D
E
F
G
H
I
J
K
L

I also need to get rid of any empty elements (the "NaN"s).

Many thanks in advance!

CodePudding user response：

You can concatenate series together using append(), and dropna() to remove the NaNs.

df.Col1.append(df.Col2).append(df.Col3).dropna()

CodePudding user response：

df is original data frame, df_ where the code will append the values.

df_ = pd.DataFrame(columns=['New'])
for ii in df.columns:
    xtr = {'New':df[ii].to_list()}
    df_=df_.append(pd.DataFrame(xtr),ignore_index=True).dropna()
print(df_)