python 3.x - pandas dataframe concatenate strings from a subset of columns and put them into a list -


i tried retrieve strings subset of columns dataframe, concatenate strings 1 string, , put these list,

# row_subset sub-dataframe of dataframe sub_columns = ['a', 'b', 'c'] string_list = [""] * row_subset.shape[0] x in range(0, row_subset.shape[0]):     y in range(0, len(sub_columns)):         string_list[x] += str(row_subset[sub_columns[y]].iloc[x])

so result like,

['row 0 string concatenation','row 1 concatenation','row 2 concatenation','row3 concatenation']

i wondering best way this, more efficiently?

i think need select columns subset [] first , sum or if need separator use join:

df = pd.dataframe({'a':list('abcdef'),                    'b':list('qwerty'),                    'c':list('fertuj'),                    'd':[1,3,5,7,1,0],                    'e':[5,3,6,9,2,4],                    'f':list('aaabbb')})  print (df)     b  c  d  e  f 0   q  f  1  5  1  b  w  e  3  3  2  c  e  r  5  6  3  d  r  t  7  9  b 4  e  t  u  1  2  b 5  f  y  j  0  4  b 
sub_columns = ['a', 'b', 'c'] print (df[sub_columns].sum(axis=1).tolist()) ['aqf', 'bwe', 'cer', 'drt', 'etu', 'fyj']  print (df[sub_columns].apply(' '.join, axis=1).tolist()) ['a q f', 'b w e', 'c e r', 'd r t', 'e t u', 'f y j']

very similar numpy solution:

print (df[sub_columns].values.sum(axis=1).tolist()) ['aqf', 'bwe', 'cer', 'drt', 'etu', 'fyj']

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