[open] Adding random number to Draw Textline?

TylerCoye

I have made a visual stimuli that consists of a series of numbers spaced apart in varying ways ( see below)

Each of the numbers is positioned using the draw text line feature with specific coordinates. I was wondering if there is anyway I can use a random number generator to add a random number in the text line, keeping the same format as I already have ( but changing the numbers shown), so that I can create a collection of the stimuli above automatically? I have a number of other test cards with varying degrees of spacing that I will apply the method too as well.

Thank you in advance,

Tyler

eduard

Hi Tyler,

Do you want to change the numbers, after you have already created such a display, or is it also fine, if you create it with random numbers right from the beginning?

The exact way of doing it depends on what it is that you need. In any case, you have to have control over which type of stimulus (line vs. number) is shown at which position. So, while creating the displays, you need to keep track of the positions, e.g. in a list that either saves the coordinates, or only the indices of them, if the coordinates are evenly spaced.

Later, you can use this list as a boolean array like way of accessing the content at every position and manipulate it in any way you like.

Does this make sense? If you need more help, just say so.

Good luck,

Eduard

TylerCoye

Hi eduard,

Thank you for your response. It is not necessary that I create the random number array later, but it is important that the coordinates of the numbers and the lines remain the same. If it is not too much trouble, could you give me an example of how I might use 'list' to save the coordinates?

This is sort of what I had in mind:

@ [-480, -384] = output is some random number; @ [-224, -384] = output is some random number, etc

In my mind, the idea is to set up the coordinate array and have it propagated with random numbers automatically. This is to say that once the list has been created for the coordinates, I want a function to take the coordinates and give a random number output. If this makes since.

Thank you for your help,

Tyler

eduard

Hi Tyler,

I assume, that your display has a grid-like structure, that is, it consists of a certain number of cells in horizontal and vertical dimension, which are evenly spaced. Is this correct?
If so, you could split the creation of this display into two functions. First, for creating the grid and assigning every position to the respective category (line vs. number). Second, adding random numbers and put them at the proper positions. So, pretty much like you already thought.
The first function could look like this:

import random

def assignPositions(shape = (width,height)):
    # width and height indicate how many elements per dimension

    # containers for the positions
    lines = []
    numbers = []

    for w in range(width):
        for h in range(height):
            # pick randomly to which group this position should belong
            random.choice([lines,numbers]).append((w,h))

    return lines,numbers

If you want to make sure that there is at least a certain numbers of positions assigned to lines/numbers you can wrap a while loop around this function and run it until the requirements are fulfilled, e.g.:

lines, numbers = assignPositions(shape = (10,10))
while len(lines) <10 or len(numbers) < 10:
    lines, numbers = assignPositions(shape = (10,10))

After you have the indices of every position in your display, you can loop over each of it, check to which group it belongs and draw the corresponding stimulus. Here, you also have to translate the position indices into real coordinates, which is not really difficult. The general idea is to divide the total space your display should cover, by the number of elements per dimension.

def drawGrid(canvas,shape,lines,numbers):
    # first, you have to translate the indices into real coordinates

    x_max = 500 # Whatever you prefer here
    y_max = 500
    step_x = 500 / width
    step_y = 500 / height

    for w in range(width):
         for h in range(height):
             pos_x = start_x + w * step_x
             pos_y = start_y + h * step_y
             # now check which stimulus is drawn at this position and draw it
             if (w,h) in lines:
                  # length indicates how long one line should be. 
                  canvas.line(pos_x -  length2/,pos_y,pos_x + length/2, pos_y) 
             elif (w,h) in numbers:
                 # I'm not sure whether this is the correct way of generatic random integers
                 # if not, you can find it out via google
                 num = random.randint(0,99)
                 canvas.text(str(num),pos_x,pos_y)

# After defining this function, you can call it:

from openexp.canvas import canvas

cv = canvas(exp)
width,height = 10,10
drawGrid(cv,(width,height),lines, numbers)
cv.show()

This should help you getting started, right? Let us know if you need more help.

Good luck,

Eduard