Extracting an item from list and displaying it as text in a sketchpad

GiorgioAlfa · March 2017

Dear Opensesame people,

I'm building a simple experiment in Opensesame and I'm stuck on a problem which has something to do with how the sketchpad script is structured by default.
My task is a version of the n-back in which items (caps lock letters) are presented one at a time. The number of letters in this study list must be random between 6 and 12, and I create the list at the beginning of the trial in an inline object. Then I call each single item of the list one at a time in a series of sketchpad in the sequence.

When I try to show the items calling them in the script where the text is suposed to be, the indication is shown in the slide as a text itself and it doesn't call the item from the list: as an example, I read [studylist[-itemnumber]] instead of C.
I tried to remove the inverted commas, but it looks like they are just a default thing in the text section of sketchpad function in Opensesame.

draw textline center=1 color=white font_bold=no font_family=mono font_italic=no font_size=18 html=yes show_if=always **text="[studylist[-12]]"** x=0 y=0 z_index=0

Any ideas?
Thank you in advance

Giorgio!

sebastiaan · March 2017

Hi Giorgio,

The standard [variable_name] notation does not allow you to do anything except refer to a variable. If you want to do more, you can embed arbitrary Python code using [=python_code] notation.

In your case, the following would seem to work:

text=[=studylist\[-12\]]

Note that the square brackets in the code need to be escaped (\[ and \]).

See also:

http://osdoc.cogsci.nl/3.1/manual/stimuli/text/#variables-and-inline-python

Cheers!
Sebastiaan

GiorgioAlfa · March 2017

Hi Sebastian
Thank you very much, the problem was that the square brackets were not escaped!
Sorry, maybe it is probably something I would have been aware of if I was more practical with python programming in general?
G

dsilva.mari · March 2017

I have a somewhat similar problem - I made a sketchpad and displayed 12 letters in it. The user should be able to click on however many letters he wants and should be able to see his selections on the screen. I stored the selections in an array, and then made the array into a string, and tried to display the variable on the sketchpad, but I get an error saying that the variable does not exist. Any ideas?

Thanks!

Mariana .

GiorgioAlfa · March 2017

I think Opensesame generates the sketchpad script in the "preparation" phase before start running the actual sequence. If the array is actually generated DURING the sequence, then the sketchpad will not be able to find the array in the preparation phase. Have you tried to embed the array code in the preparation phase? You can do it with an inline object, writing the code in the "prep" sheet!

dsilva.mari · March 2017

Hi Giorgio! Using a sketchpad item wasn't doing the trick for me ( even if I defined the variable in the preparation phase) , so I ended up using widgets and creating a form -- I defined a variable to the beginning of the experiment and managed to add the letters that the user clicked on, and then displayed it with a custom widget that returns user input.

Jarik · March 2017

Hi,

Maybe using a feedback item also helps (for future experiments):
http://osdoc.cogsci.nl/3.1/manual/stimuli/visual

Best,
Jarik

HenkvanSteenbergen · November 2021

I have a related question. Is it possible to use the square-bracket notation (in a feedback item) to show the content of an element of an array created in JavaScript (for an online experiment)?

For example after a javascript inline with this:

vars.accblock1 = []
for (let i = 1; i < 12 ; i++) {
  vars.accblock1[i] = 1;
}

How can I refer to vars.accblock1[1] in the feedback item script? The solution suggested with = seems not to work (a runtime error aborts the experiment), likely because = only works for variables created in python code?:

text="[=accblock1\\[1\\]]"

sebastiaan · November 2021

Hi @HenkvanSteenbergen ,

It's not terribly elegant, but you could include the index (i ) in te variable name, like so:

vars.accblock1 = []
for (let i = 1; i < 12 ; i++) {
  vars['accblock1_' + i] = 1
}

And then you can refer to the variable as [accblock1_1] in a feedback item.

— Sebastiaan

HenkvanSteenbergen · November 2021

That works! Thanks Sebastiaan!

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Extracting an item from list and displaying it as text in a sketchpad

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Extracting an item from list and displaying it as text in a sketchpad

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