Slider widget in Expyriment

anapinho

Hello,
I would like to build a slider widget to get ratings of images under Expyriment. The idea is to get a score from the subject regarding images on display for ~5sec. The participant has to press a button to slide left and another one to slide right in order to set the cursor in a specific position related to the value of their score. Would it be possible to get a demo snippet of code on how to build this under Expyriment?

Thank you very much in advance.
Best,
Ana Luísa

fladd

Hi anapinho,

not a slider widget, but a similar solution that works with radio buttons:

#!/bin/env python

""" A radiobutton example in Expyriment."""

__author__ = "Florian Krause <florian@expyriment.org>"


from expyriment import control, stimuli, misc


control.set_develop_mode(True)
exp = control.initialize()
exp.mouse.show_cursor()

question = stimuli.TextScreen("The answer to life, the universe and everything?","")
question.present()
question.present() # Twice for double buffering!

answers_pos = [["1", -300], ["2", -200], ["3", -100], ["42", 0], ["7", 100], ["99", 200], ["100", 300]]

answer_canvas = stimuli.Canvas((700, 200))
answers = []
buttons = []
for answer in answers_pos:
    a = stimuli.TextLine(answer[0], position=(answer[1], -30))
    a.plot(answer_canvas)
    b = stimuli.Rectangle((20, 20), line_width = 2, position=(answer[1], 0))
    b.ticked = False
    b.plot(answer_canvas)
    buttons.append(b)

answer_canvas.present(clear=False)
answer_canvas.present(clear=False)  # Twice for double buffering!

tick = stimuli.Rectangle((10, 10))
tick.preload()

untick = stimuli.Rectangle((10, 10), colour=exp.background_colour)
untick.preload()

while True:
    exp.keyboard.check()  # Press ESC to exit
    if exp.mouse.check_button_pressed(0):
        exp.mouse.wait_press(0, wait_for_buttonup=True)
        pos = exp.mouse.position
        for button in buttons:
            if button.overlapping_with_position(pos, mode="surface"):
                if button.ticked:
                    button.ticked = False
                    untick.position = button.position
                    untick.present(clear=False)
                    untick.present(clear=False)  # Twice for double buffering!
                else:
                    button.ticked = True
                    tick.position = button.position
                    tick.present(clear=False)
                    tick.present(clear=False)  # Twice for double buffering!

You could modify it to work with the keyboard instead of with the mouse.

Hope this helps!

anapinho

Thank you for this. In the end, I decided for a different solution but I will keep this for the future.

PMKraemer

Hello anapinho,
would you be so kind to tell how you did it? I'm facing a very similar problem than you did. Would be super helpful to get some idea

PMKraemer

okay I've approached my problem for a willingness-to-pay task for a snack like this:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed May  9 17:20:15 2018

@author: peterkraemer
"""

from expyriment import control, stimuli

#control.set_develop_mode(True)

exp = control.initialize()
######################  STIMULI  ######################
#   creating elements on screen

# picture
path_picture =   '/Users/peterkraemer/Desktop/experiment/PICTURES/snack1.bmp'
picture      =   stimuli.Picture(path_picture, position=(0,200))

# bar
barLength = 300
barThick = 10
posBar=(0,-100)
bar = stimuli.Rectangle((barLength,barThick),corner_rounding=None,position=posBar)
bar.preload()
barEndLeft = stimuli.Rectangle((5,barThick*3),position=((-(barLength+2)/2), posBar[1]))
barEndLeft.preload()
barEndRight = stimuli.Rectangle((5,barThick*3),position=(((barLength+2)/2), posBar[1]))
barEndRight.preload()

# slider
posSlider = (0,posBar[1]) # initial position of the slider

# sliding function
def sliding(pos,commit):
    while commit==0:
        # create a composition to show multiple elements at the same time
        composition = stimuli.BlankScreen()
        picture.plot(composition)
        bar.plot(composition)
        barEndLeft.plot(composition)
        barEndRight.plot(composition)
        slider = stimuli.Rectangle((3,30),position=pos, colour = (194, 24, 7))
        slider.plot(composition)
        composition.present()
        # participants can use left and right arrow to adjust slider position & commit with enter
        key, rt = exp.keyboard.wait(process_control_events=True)
        if key == 13:
            commit = 1
            return pos[0]
        elif key == 275:
            pos = (pos[0]+10, pos[1])
            if pos[0] > barLength/2: # fixes upper end of the scale
                pos = (barLength/2,pos[1])
        elif key == 276:
            pos = (pos[0]-10, pos[1])
            if pos[0] < -barLength/2: # fixes lower end of the scale
                pos = (-barLength/2,pos[1])

# position - money translation
scaleMax = 5 # upper end of the scale
moneyPerPixel=scaleMax/barLength # = CHF/Pixel

## start ##
control.start(exp,skip_ready_screen=True)

val = (sliding(posSlider,0)-(-barLength/2))*moneyPerPixel
print(val)

## end ##
control.end()

certainly not the most elegant way but anywayne