Visual Analog Scale

[Roy]

Hi,

Is there any example program for VAS (visual analog scale) to get participants' data?
Or, any functions for it?

Thanks

[Jeff]

There is no built-in VAS GUI object but it's possible to create one. Here is an example that adds a VAS slider to the ortho layer. The user can select a value between 0-10:

import viz
import viztask

VAS_MOVE_EVENT = viz.getEventID('VAS_MOVE_EVENT')
VAS_CONFIRM_EVENT = viz.getEventID('VAS_CONFIRM_EVENT')

class SliderVAS:
	"""Add a VAS slider to the ortho layer"""
	
	def __init__(self, text, scale=2, left=viz.KEY_LEFT, right=viz.KEY_RIGHT, confirm=viz.KEY_RETURN):
		# parent the slider, slider numbers, and text to a group object
		self._group = viz.addGroup(parent=viz.ORTHO)
		viz.link(viz.CenterCenter,self._group)

		self.slider = viz.addSlider()
		self.slider.setParent(self._group)
		self.slider.setScale([scale,1,1])
		self.slider.setTickSize(.2,1)
		sliderWidth = self.slider.getBoundingBox()[0]
		stepWidth = sliderWidth/11

		self._text = viz.addText(text,parent=self._group)
		self._text.alignment( viz.ALIGN_CENTER_BOTTOM )
		self._text.setPosition(-0,-100)
		self._text.fontSize(45)

		for i in range(0,11):
			slidernum = viz.addText(str(i),parent=self._group)
			slidernum.alignment(viz.TEXT_CENTER_BOTTOM)
			slidernum.setPosition(-sliderWidth/2*0.89 +(i*stepWidth*0.98),75,0)
			slidernum.fontSize(40)
			
		self._waitLeft = viztask.waitKeyDown(left)
		self._waitRight = viztask.waitKeyDown(right)
		self._waitConfirm = viztask.waitKeyDown(confirm)
		self._sliderStep = 0.1
		self._sliderschedule = viztask.schedule( self._moveSlider() )

	# get the slider value as a number between 0 and 10
	def getValue(self):
		value = int(round((self.slider.get() * 10.0)))
		return value

	def _moveSlider(self):
		while True:
			d = yield viztask.waitAny([self._waitLeft,self._waitRight,self._waitConfirm])
			if d.condition is self._waitLeft:
				self.slider.set(self.slider.get()+ self._sliderStep * -1)
				viz.sendEvent(VAS_MOVE_EVENT)
			elif d.condition is self._waitRight:
				self.slider.set(self.slider.get()+ self._sliderStep)
				viz.sendEvent(VAS_MOVE_EVENT)
			else:
				viz.sendEvent(VAS_CONFIRM_EVENT)
				break
		self._group.visible(viz.OFF)


if __name__ == '__main__':
	import vizinfo	
	
	viz.go()
	viz.window.setSize(1280,720)
	viz.clearcolor(viz.SLATE)
	vizinfo.InfoPanel('Use left and right arrow keys to move the slider\ntick and the Enter key to select a value')
	
	questions = ['How much do you like pizza?',
				 'How much do you like chocolate?']
	def surveyTask():		
		for question in questions:
			vas = SliderVAS(question)
			yield viztask.waitEvent(VAS_CONFIRM_EVENT)
			print 'Value:',vas.getValue()
		print 'Survey complete'
		
	viztask.schedule( surveyTask() )