[open] Define variable with inline code

Stefan

Hi,

Short question (I think). We're busy setting up an experiment and for each condition we want to show a random picture. Of course we also want to randomize the order of conditions. The idea is to randomize the order of the pictures in the loop, while predefining the order of the conditions (agency and valence) and then run through the loop in a random order.

The problem is how to place pictures from python into the loop, using inline scripting.

The code we have so far is this:

agency = [1,1,1,1,2,2,2,2,]
val = [1,1,2,2,1,1,2,2]
names = [1,2,3,4,5,6,7,8]
import random
random.shuffle(names)

so the resulting loop we want to go through could look like this:

Hopefully, you could help us with the code that defines our loop. Many thanks,

Stefan

lvanderlinden

Hi Stefan,

I think you don't need to specify the values of your variables in a loop item in the GUI anymore. You can simply set() the variables in an inline_script item.

More specifically:

Declare your variable lists:

Append an inline_script item to your block sequence and place the following code in its Prepare phase tab:

# Your code:
agency = [1,1,1,1,2,2,2,2]
val = [1,1,2,2,1,1,2,2]
names = [1,2,3,4,5,6,7,8]
import random
random.shuffle(names)

# Make lists global such that they are available
# in future inline_script items as well:
global agency, val, names

Set number of cycles:

Set the number of cycles in your block loop to the length of your lists (i.e. in your case 8 cycles).

Determine the trial values:

Append an inline_script item to the beginning of your trial sequence and place the following code in its Prepare phase tab (see comments for more info):

# Declare the variables of the current trial,
# which is equivalent to reading trial
# values from the loop item.

# We use the pop() function to draw one item from
# the previously-defined lists. 'Popping' means that
# the item is drawn without replacement.

# Note that the pop() function starts drawing
# items from the END of the lists, so we start
# with agency = 2 and val = 2.
# Simply re-order the lists in 'declare_lists'
# to change this.

trial_ag = agency.pop()
trial_val = val.pop()
trial_name = names.pop()

# Finally, we SET the trial variables
# for future use in the interface (e.g. a sketchpad
# item, the logger item, etc. - see 'show_trial_vars'
# for an example)

# For more info, see:
# http://osdoc.cogsci.nl/python-inline-code/experiment-functions/#experiment.set

exp.set("trial_ag", trial_ag)
exp.set("trial_val", trial_val)
exp.set("trial_name", trial_name)

Now you can use the variables 'trial_ag', 'trial_val', and 'trial_name' as you would use them if they were defined in a loop item.

Eventually, your overview area should look something like this:

For a working example experiment, see:

• http://pastebin.com/qrHZNMvP (download, change the extension from .txt into .opensesame and open as normally)

Does that make sense? Please let us know if you have any further questions!

Best,

Lotje