if statement [variable]=None

Jarek · April 2017

Hi all,

I have a bunch of variables in a loop (e.g., V1, V2, V3) and some items to be run by a sequence associated with that loop (e.g., item1, item2, item3). I would like the sequence to run items only if a corresponding variable is not empty. So far I tried specifying it by an if statement in the sequence:

run item1 "[V1]!=None"
run item2 "[V2]!=None"
run item3 "[V3]!=None"

But this doesn't work, probably because OS thinks I mean a string "None" rather than an expression for an empty variable. Is there another way of doing that?

Many thanks!

Jarek

sebastiaan · April 2017

Hi Jarek,

I would like the sequence to run items only if a corresponding variable is not empty.

Strictly speaking, there is no such thing as an empty variable. Either it doesn't exist, in which case you would get a "variable does not exist" error, or it exists and therefore has some value. You probably mean an empty string (''):

run item1 "[V1] != ''"

Does that help at all?

Cheers,
Sebastiaan

Jarek · April 2017

Hi Sebastiaan,

Thanks for a quick reply. It does help indeed! I actually tested this solution before, but in a very sloppy way. Now I did it properly and all works well. Thank you!

ticky · May 2017

Hi all!
I have somehow the same problem, but the solution doesnt work for me.
I want to have some extra pictures and questions in my desing, lets say every 3 trials. In order to define that, the variable "Extra picture" and "Extra question" are filled with "na" in the loop, lets say in the 1rst and 2nd row. The error I get is the '.jpg' file does not exist.

My script looks like this:
run Pract_Q1_1 "[Extra_picture] !='na '"
run Pract_Sound1_1 "[Extra_Question] !='na'"

I have tried also the line: =(self.get('count_trial_sequence_1')+1)%3 == 0, with no success...

Any ideas?

Thank you very much!

Jarik · May 2017

Hi Jarek,

There a space in your code: run Pract_Q1_1 "[Extra_picture] !='na '"

'na' is not 'na '

Best,
Jarik

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