How to combine multiple columns into one in spark logistic regression?

vectorAssembler = VectorAssembler(inputCols = ['_c0', '_c0', '_c0', '_c3', '_c4', '_c5', '_c6', '_c7', \
'_c8', '_c9', '_c10', '_c12', '_c13','_c14','_c14','_c16','_c17','_c18','_c19','_c20','_c21','_c22'\
,'_c23','_c24','_c25','_c26','_c27','_c28','_c29'], outputCol = 'features')

transformed_df = vectorAssembler.transform(df)
transformed_df.select(["features","_c30"]).show()