How to refer to a column number by a variable

jochen
New Member

Posts: 10

How to refer to a column number by a variable Apr 16, 2020 22:46:11 GMT

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Post by jochen on Apr 16, 2020 22:46:11 GMT

Hi!

I'm trying to code an RSVP task in which each item of my RSVP stream is a column in the table. Now I want to change the color of certain items.
I tried the code below (sorry for the clumsy RGB specification, I didn't now how to specify a tuple in a variable). However, it throws an ERROR: at_non_integer. I also tried @$item_column and @($item_column), but with the same error. Is it not possible to refer to a table column by a variable?

Best,
Jochen

table rsvp_design
5 9 "1" "2" "3" "4" "X" "6" "7" "8" "B" "0" "1" "2" "3" "4" "5"
5 10 "1" "2" "3" "4" "B" "6" "7" "8" "9" "X" "1" "2" "3" "4" "5"

task rsvp
table rsvp_design
keys space
set $loop_counter 1
while $loop_counter < 16
set $item_column expression $loop_counter + 2
set $R 255
set $G 255
set $B 255
if $loop_counter == @1 or $loop_counter == @2
set $G 0
set $B 0
fi
show text @item_column 0 0 $R $G $B
while-end

Last Edit: Apr 16, 2020 22:57:52 GMT by jochen

PsyToolkit
Administrator

Posts: 547

How to refer to a column number by a variable Apr 17, 2020 0:25:02 GMT jochen likes this

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Post by PsyToolkit on Apr 17, 2020 0:25:02 GMT

The value specified after a column identifier always must be a number (that is, no variable allowed as in your example).

With this type of experiment, it is sometimes easier to write a script (on your own computer) to create a sequence and put that in a table.

You can then have each letter as a table row and use the "fixed" option to have it exactly in the order as you wish. I think that is what I would do.

jochen
New Member

Posts: 10

How to refer to a column number by a variable Apr 17, 2020 10:26:50 GMT

Quote

Post by jochen on Apr 17, 2020 10:26:50 GMT

Thanks for the quick reply. I will try next time (I didn't know that there could be several tables per experiment), this time I had already solved it by unrolling the loop, which was not too bad because it contained only 15 items. But of course this code will be somewhat hard to maintain: if I want to change some stimulus property, I will have to change it in 15 places. So your approach is probably preferable.