Shuffling a list in a loop once, then running it multiple times

OmerBirka

Hello,

I have a loop that runs several times that should random a variable value (all values are letters, in my case). I have 18 values, and the loop runs 7 times in each sequence. Also, I don't want the same value to appear more than once. I thought I should use the "shuffle" command in the loop item and pick "sequential" under "Order", but while it does seem to shuffle the list, I guess the loop runs itself and reshuffles the list in each loop-run so I end up getting a certain letter (variable value) more than once in each sequence, occasionally.

Any idea what am I getting wrong?

Thank you,
Omer

sebastiaan

Hi Omer,

Hmm, it's not entirely clear to me what you want to do.

• The title of your discussion suggests that you want to determine the order of a loop once, and then run the loop in that same order multiple times. Do I understand that correctly?
• What kind of constraints do you want to apply to the order? Right now, target_letter has 18 unique values, so I don't see how repetitions within a loop can occur, nor how you can avoid repetitions if you run the loop 7 times.

Cheers!
Sebastiaan

OmerBirka

Hey Sebastiaan,

First, thank you for you answer. I havn't managed to get to this project lately but I'm getting back to it now (that's why it took me so long to respond back. apologies).

So I guess I wasn't clear enough as of what is it that I'm trying to achieve. Maybe I'll open by briefly describing how 1 trial in my experiment should look like -
1. A letter (from a bank of 18 unique letters in total) should appear.
2. 4 consecutive (timed) tasks appear.
3. This sequence of events should appear for 6 more times or 7 in total, so - 7 letters and 28 tasks in total.
4. Subjects will report the list of letters into a text input form.

That's the basic structure of a trial in my experiement.
Now, for what I can't figure out - I want the order of letters to be random and with no repeats within each trial. From your 2nd note I understand that my understanding wasn't correct - the way it's built right now (same as in the picture above) I was basicly creating a different list each time and calling the 'target_letter' gave me the first value of the list each time, that's why I'm getting repetitions.

While trying to fix this issue now, I tried to call 'target_letter' more than once within a loop to see if that would do the trick but that resulted in getting the same value for 'target_letter' for the whole loop. Plus, it felt like the design was quite 'stupid' so I'm not sure that's the way I should be heading with this.

I hope this provides more info,
Thanks again,
Omer

eduard

Hi Omer,

If you put all letters in one row each (column name is target letter or whatever), and set repeat to something around 0.4. The loop will iterate 7 times (tweak the value to get exactly 7 and not 6 or 8) and you have 7 unique letters.

Does that help?

Eduard