If this template helps then use it. If not then just delete and start from scratch.

**OS** (e.g. Win10):

**PsychoPy version** 2020.2.4:

**What are you trying to achieve?:

I am programming an experiment that produces series of numbers that either update randomly or update based on a rule (a mathematical operation). I have the list of rules programmed containing a bunch of dictionaries:

```
conditionContainer = [
{'difficulty': 'easy', 'steps': [1]},
{'difficulty': 'easy', 'steps': [2]},
{'difficulty': 'easy', 'steps': [3]},
{'difficulty': 'easy', 'steps': [4]},
{'difficulty': 'easy', 'steps': [-1]},
{'difficulty': 'easy', 'steps': [-2]},
{'difficulty': 'easy', 'steps': [-3]},
{'difficulty': 'easy', 'steps': [-4]},
{'difficulty': 'hard', 'steps': [1, 2]},
{'difficulty': 'hard', 'steps': [2, 3]},
{'difficulty': 'hard', 'steps': [-2, -1]},
{'difficulty': 'hard', 'steps': [-3, -2]},
{'difficulty': 'hard', 'steps': [-2, 1]},
{'difficulty': 'hard', 'steps': [-2, -3]},
{'difficulty': 'hard', 'steps': [2, -1]},
{'difficulty': 'hard', 'steps': [-2, 3]}]
```

The program alternates between rule and non-rule phases. When in a non-rule phase, the program randomly draws upon a rule and then updates the number on-screen based on one of the steps in the rule. In a rule-phase, the program picks one of those rules and then consistently applies it over a set number of trials until a certain number of trials is reached. Currently, the experiment works, but I am trying to modify it so that when a rule is selected, IF it is a rule phase, then that rule is dropped from the list so it will not be chosen again once it becomes time to select a new rule. Here is the function that determines the rule (it is located in the begin experiment tab of the first screen):

```
def determineCurrentRule(phaseParameters, currentTarget, conditionContainer, targetBounds):
## takes as input phase information, the current target, all conditions, and target boundaries
## randomly iterates through the rules until it finds one that stays in bounds
## make a list of condition indices
availableIndices = list(range(len(conditionContainer)))
out = 1
while out:
try:
## randomly sample from conditions
## the line below is the one that will fail if all conditions are exhausted
chosenIndex = availableIndices[random.randint(0, len(availableIndices))]
## update the current rule
currentRule = conditionContainer[chosenIndex]
## if a condition is successfully drawn, drop it from the available indices list
availableIndices.remove(chosenIndex)
out = 0
except:
## if all conditions are exhausted
## regenerate the target stimulus to be close to the median of possible targets
currentTarget = random.randint(currentTarget - 2, currentTarget + 2)
## refresh available indicies so all rules can be sampled again
availableIndices = list(range(len(conditionContainer)))
return([currentRule, currentTarget])
```

**What did you try to make it work?:**

Within the “try” segment of the above function, I tried adding this:

```
if phaseParameters['phaseId'] == 'rulePhase':
availableIndices.remove(chosenIndex)
```

Within the “except” segment of the above function, I commented out this:

```
## refresh available indicies so all rules can be sampled again
availableIndices = list(range(len(conditionContainer)))
```

**What specifically went wrong when you tried that?:**

The experiment still runs, but it is not removing the rules from the availableIndices after a rule has been successfully drawn.