How can we convert pandas dataframe two columns to python list after merging two columns vertically?-CodePudding

I have a dataframe...

print(df)       
Name    ae_rank    adf      de_rank
a       1          lk       4   
b       2          lp       5
c       3          yi       6

How can I concat ae_rank column and de_rank column vertically and convert them into python list.

Expectation...

my_list = [1, 2, 3, 4, 5, 6]

CodePudding user response：

Simpliest is join lists:

my_list =  df['ae_rank'].tolist()   df['de_rank'].tolist()

If need reshape DataFrame with DataFrame.melt:

my_list = df.melt(['Name','adf'])['value'].tolist()
print (my_list )
[1, 2, 3, 4, 5, 6]

CodePudding user response：

Another option is

my_list = df[['ae_rank', 'de_rank']].T.stack().tolist()
#[1, 2, 3, 4, 5, 6]

CodePudding user response：

Most efficiently, use filter to select the columns by name that include "_rank" and use the underlying numpy array with ravel on the 'F' order (column major order):

my_list = df.filter(like='_rank').to_numpy().ravel('F').tolist()

output: [1, 2, 3, 4, 5, 6]