text: #!/usr/bin/env python2
  # -*- coding: utf-8 -*-
  ##################################################
  # GNU Radio Python Flow Graph
  # Title: selector
  # Author: Alexandros-Apostolos A. Boulogeorgos
  # Description: This example demonstrate the use of the "selector" operator
  # Generated: Sun Oct  6 08:20:39 2019
  ##################################################
  
  if __name__ == '__main__':
      import ctypes
      import sys
      if sys.platform.startswith('linux'):
          try:
              x11 = ctypes.cdll.LoadLibrary('libX11.so')
              x11.XInitThreads()
          except:
              print "Warning: failed to XInitThreads()"
  
  from PyQt4 import Qt
  from PyQt4.QtCore import QObject, pyqtSlot
  from gnuradio import analog
  from gnuradio import audio
  from gnuradio import blocks
  from gnuradio import eng_notation
  from gnuradio import gr
  from gnuradio import qtgui
  from gnuradio.eng_option import eng_option
  from gnuradio.filter import firdes
  from grc_gnuradio import blks2 as grc_blks2
  from optparse import OptionParser
  import sip
  import sys
  
  
  class selector(gr.top_block, Qt.QWidget):
  
      def __init__(self):
          gr.top_block.__init__(self, "selector")
          Qt.QWidget.__init__(self)
          self.setWindowTitle("selector")
          try:
              self.setWindowIcon(Qt.QIcon.fromTheme('gnuradio-grc'))
          except:
              pass
          self.top_scroll_layout = Qt.QVBoxLayout()
          self.setLayout(self.top_scroll_layout)
          self.top_scroll = Qt.QScrollArea()
          self.top_scroll.setFrameStyle(Qt.QFrame.NoFrame)
          self.top_scroll_layout.addWidget(self.top_scroll)
          self.top_scroll.setWidgetResizable(True)
          self.top_widget = Qt.QWidget()
          self.top_scroll.setWidget(self.top_widget)
          self.top_layout = Qt.QVBoxLayout(self.top_widget)
          self.top_grid_layout = Qt.QGridLayout()
          self.top_layout.addLayout(self.top_grid_layout)
  
          self.settings = Qt.QSettings("GNU Radio", "selector")
          self.restoreGeometry(self.settings.value("geometry").toByteArray())
  
          ##################################################
          # Variables
          ##################################################
          self.uiselector = uiselector = 0
          self.samp_rate = samp_rate = 100000
  
          ##################################################
          # Blocks
          ##################################################
          self._uiselector_options = (0, 1, )
          self._uiselector_labels = ('Sound card', 'Signal source', )
          self._uiselector_tool_bar = Qt.QToolBar(self)
          self._uiselector_tool_bar.addWidget(Qt.QLabel('Source selector'+": "))
          self._uiselector_combo_box = Qt.QComboBox()
          self._uiselector_tool_bar.addWidget(self._uiselector_combo_box)
          for label in self._uiselector_labels: self._uiselector_combo_box.addItem(label)
          self._uiselector_callback = lambda i: Qt.QMetaObject.invokeMethod(self._uiselector_combo_box, "setCurrentIndex", Qt.Q_ARG("int", self._uiselector_options.index(i)))
          self._uiselector_callback(self.uiselector)
          self._uiselector_combo_box.currentIndexChanged.connect(
          	lambda i: self.set_uiselector(self._uiselector_options[i]))
          self.top_layout.addWidget(self._uiselector_tool_bar)
          self.qtgui_freq_sink_x_0 = qtgui.freq_sink_c(
          	1024, #size
          	firdes.WIN_BLACKMAN_hARRIS, #wintype
          	0, #fc
          	samp_rate, #bw
          	"", #name
          	1 #number of inputs
          )
          self.qtgui_freq_sink_x_0.set_update_time(0.10)
          self.qtgui_freq_sink_x_0.set_y_axis(-140, 10)
          self.qtgui_freq_sink_x_0.set_y_label('Relative Gain', 'dB')
          self.qtgui_freq_sink_x_0.set_trigger_mode(qtgui.TRIG_MODE_FREE, 0.0, 0, "")
          self.qtgui_freq_sink_x_0.enable_autoscale(False)
          self.qtgui_freq_sink_x_0.enable_grid(False)
          self.qtgui_freq_sink_x_0.set_fft_average(1.0)
          self.qtgui_freq_sink_x_0.enable_axis_labels(True)
          self.qtgui_freq_sink_x_0.enable_control_panel(False)
          
          if not True:
            self.qtgui_freq_sink_x_0.disable_legend()
          
          if "complex" == "float" or "complex" == "msg_float":
            self.qtgui_freq_sink_x_0.set_plot_pos_half(not True)
          
          labels = ['', '', '', '', '',
                    '', '', '', '', '']
          widths = [1, 1, 1, 1, 1,
                    1, 1, 1, 1, 1]
          colors = ["blue", "red", "green", "black", "cyan",
                    "magenta", "yellow", "dark red", "dark green", "dark blue"]
          alphas = [1.0, 1.0, 1.0, 1.0, 1.0,
                    1.0, 1.0, 1.0, 1.0, 1.0]
          for i in xrange(1):
              if len(labels[i]) == 0:
                  self.qtgui_freq_sink_x_0.set_line_label(i, "Data {0}".format(i))
              else:
                  self.qtgui_freq_sink_x_0.set_line_label(i, labels[i])
              self.qtgui_freq_sink_x_0.set_line_width(i, widths[i])
              self.qtgui_freq_sink_x_0.set_line_color(i, colors[i])
              self.qtgui_freq_sink_x_0.set_line_alpha(i, alphas[i])
          
          self._qtgui_freq_sink_x_0_win = sip.wrapinstance(self.qtgui_freq_sink_x_0.pyqwidget(), Qt.QWidget)
          self.top_layout.addWidget(self._qtgui_freq_sink_x_0_win)
          self.blocks_throttle_0 = blocks.throttle(gr.sizeof_gr_complex*1, samp_rate,True)
          self.blocks_float_to_complex_0 = blocks.float_to_complex(1)
          self.blks2_selector_0 = grc_blks2.selector(
          	item_size=gr.sizeof_gr_complex*1,
          	num_inputs=2,
          	num_outputs=1,
          	input_index=uiselector,
          	output_index=0,
          )
          self.audio_source_0 = audio.source(samp_rate, '', True)
          self.analog_sig_source_x_0 = analog.sig_source_c(samp_rate, analog.GR_COS_WAVE, 1000, 1, 0)
  
          ##################################################
          # Connections
          ##################################################
          self.connect((self.analog_sig_source_x_0, 0), (self.blocks_throttle_0, 0))    
          self.connect((self.audio_source_0, 0), (self.blocks_float_to_complex_0, 0))    
          self.connect((self.blks2_selector_0, 0), (self.qtgui_freq_sink_x_0, 0))    
          self.connect((self.blocks_float_to_complex_0, 0), (self.blks2_selector_0, 0))    
          self.connect((self.blocks_throttle_0, 0), (self.blks2_selector_0, 1))    
  
      def closeEvent(self, event):
          self.settings = Qt.QSettings("GNU Radio", "selector")
          self.settings.setValue("geometry", self.saveGeometry())
          event.accept()
  
      def get_uiselector(self):
          return self.uiselector
  
      def set_uiselector(self, uiselector):
          self.uiselector = uiselector
          self._uiselector_callback(self.uiselector)
          self.blks2_selector_0.set_input_index(int(self.uiselector))
  
      def get_samp_rate(self):
          return self.samp_rate
  
      def set_samp_rate(self, samp_rate):
          self.samp_rate = samp_rate
          self.qtgui_freq_sink_x_0.set_frequency_range(0, self.samp_rate)
          self.blocks_throttle_0.set_sample_rate(self.samp_rate)
          self.analog_sig_source_x_0.set_sampling_freq(self.samp_rate)
  
  
  def main(top_block_cls=selector, options=None):
  
      from distutils.version import StrictVersion
      if StrictVersion(Qt.qVersion()) >= StrictVersion("4.5.0"):
          style = gr.prefs().get_string('qtgui', 'style', 'raster')
          Qt.QApplication.setGraphicsSystem(style)
      qapp = Qt.QApplication(sys.argv)
  
      tb = top_block_cls()
      tb.start()
      tb.show()
  
      def quitting():
          tb.stop()
          tb.wait()
      qapp.connect(qapp, Qt.SIGNAL("aboutToQuit()"), quitting)
      qapp.exec_()
  
  
  if __name__ == '__main__':
      main()
  