Selector blks2_selector from grc_gnuradio import blks2 as grc_blks2 grc_blks2.selector( item_size=$type.size*$vlen, num_inputs=$num_inputs, num_outputs=$num_outputs, input_index=$input_index, output_index=$output_index, ) set_input_index($input_index) set_output_index($output_index) Type type enum Complex complex size:gr.sizeof_gr_complex Float float size:gr.sizeof_float Int int size:gr.sizeof_int Short short size:gr.sizeof_short Byte byte size:gr.sizeof_char Num Inputs num_inputs 2 int Num Outputs num_outputs 2 int Input Index input_index 0 int Output Index output_index 0 int Vec Length vlen 1 int $vlen > 0 in $type $vlen $num_inputs out $type $vlen $num_outputs Connect the sink at input index to the source at output index. Leave all other ports disconnected.