# Randomly selecting and grouping rows from a conditions file

**URL:** <https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502>\
**Category:** Builder\
**Created:** [May 11, 2018, 8:31pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502 "2018-05-11T20:31:47Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Lyam\_Bailey](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lyam\_Bailey](https://discourse.psychopy.org/u/Lyam_Bailey)\
**Post date:** [May 11, 2018, 8:31pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/1 "2018-05-11T20:31:47Z")

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Apologies if this issue has been posted before. I have a conditions file called cond.xlsx with a single column and 6 rows, each containing a different item of fruit.

![Capture](https://us1.discourse-cdn.com/flex002/uploads/psychopy/original/3X/e/5/e5224b24c254d7b666ba698ce48000bbe1d9ddec.png)

I would like to write a code component at the beginning of my experiment which randomly sorts the rows into three conditions, each containing 2 rows. Ideally this would create a ‘temporary’ dict object (apologies if I’m using incorrect terminology) that would allow me to call rows from each condition in subsequent loops in the experiment.

Here is my code:

> conditions = data.importConditions(u’cond.xlsx’)  
> shuffle(conditions)  
> cond\_A = conditions[0:2]  
> cond\_B = conditions[3:4]  
> cond\_C = conditions[5:6]

I would then call specific conditions in subsequent loops:

![Capture2](https://us1.discourse-cdn.com/flex002/uploads/psychopy/original/3X/2/2/22634265ca871ff45cc30852165fa560f47ca9d1.png)

Ultimately I would like a way to record which items of fruit were assigned to each condition at the end of the experiment. However, when I try to run the experiment as-is, I get the following error

![Capture3](https://us1.discourse-cdn.com/flex002/uploads/psychopy/original/3X/c/b/cb95bd7def72666493a7fed7148801960a2bc5ee.png)  
################

If anyone can suggest a fix (and/or a way to save a record of which rows/items of fruit were assigned to each condition) I would be very grateful for the advice. Thanks in advance!

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**Author:** ![Michael](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/michael/32/16_2.png) [@Michael](https://discourse.psychopy.org/u/Michael)\
**Post date:** [May 12, 2018, 6:29am UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/2 "2018-05-12T06:29:07Z")

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The selected rows field has to contain integers (ie the indices of the rows, not the content of the rows themselves).

You can achieve what you want without any code.

- Put some fixed ranges in each of your loops (eg `[0, 1]` followed by `[2, 3]`, etc).
- Set each loop to be random but supply a common seed value so that the randomisation is constant across each loop.
- I guess you want the randomisation to vary across subjects however, so enter a new seed value on each session into the information dialog at the start of the experiment, and refer to that variable from the `expInfo` dialog in each seed field.

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<div class="post-metadata">

**Author:** ![Lyam\_Bailey](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lyam\_Bailey](https://discourse.psychopy.org/u/Lyam_Bailey)\
**Post date:** [May 12, 2018, 2:55pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/3 "2018-05-12T14:55:54Z")

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Hi Michael

Thanks for the reply! I’m having trouble calling the `expInfo` as you suggested. I entered a new row in ‘Experiment settings’:

![Capture](https://us1.discourse-cdn.com/flex002/uploads/psychopy/original/3X/a/c/ac16ebc2298ef3ccc726325b097c80332e492084.png)

and then entered `expInfo.setSeed` in the seed field for each loop. This causes the following error:

`AttributeError: 'dict' object has no attribute 'setSeed'`

I also tried automating the process by instead creating a code component with  
setSeed = random.randint(0,1000) # should select a random seed value between 0 and 1000

This runs fine (and seems to be selecting random rows, as intended), but after running the experiment a few times I realized it’s pulling the SAME selection of rows each time, so `random.randint` must be assigning the same value to `setSeed` each time…?

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<div class="post-metadata">

**Author:** ![Michael](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/michael/32/16_2.png) [@Michael](https://discourse.psychopy.org/u/Michael)\
**Post date:** [May 13, 2018, 8:46pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/4 "2018-05-13T20:46:33Z")

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> [@Lyam\_Bailey](#):
>
> `expInfo.setSeed` in the seed field for each loop.

The dot notation gives you access to the methods of the dictionary class, things like `.keys()`, `copy()`, etc. You look up individual values in Python dictionaries like this:

```
expInfo['setSeed']

```

See [Python - Dictionary](https://www.tutorialspoint.com/python/python_dictionary.htm)

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<div class="post-metadata">

**Author:** ![Lyam\_Bailey](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lyam\_Bailey](https://discourse.psychopy.org/u/Lyam_Bailey)\
**Post date:** [May 14, 2018, 1:15pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/5 "2018-05-14T13:15:56Z")

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Ah! That makes sense. I tried using expInfo[‘setSeed’] and got the following error:

> File “mtrand.pyx”, line 684, in mtrand.RandomState.seed (numpy\random\mtrand\mtrand.c:13996)  
> TypeError: Cannot cast array from dtype(‘\<U2’) to dtype(‘int64’) according to the rule ‘safe’

My understanding is that the value from expInfo[‘setSeed’] should be converted to float, which I tried to do with a code component:

> randValue = expInfo[‘setSeed’]  
> randSeed = map(float, randValue)

But no luck! Can you suggest a work around? Again, thanks in advance for the help 🙂

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<div class="post-metadata">

**Author:** ![Michael](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/michael/32/16_2.png) [@Michael](https://discourse.psychopy.org/u/Michael)\
**Post date:** [May 14, 2018, 9:44pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/6 "2018-05-14T21:44:10Z")

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Try:

```
eval(expInfo['setSeed'])
```

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<div class="post-metadata">

**Author:** ![Lyam\_Bailey](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lyam\_Bailey](https://discourse.psychopy.org/u/Lyam_Bailey)\
**Post date:** [May 17, 2018, 1:40pm UTC](https://discourse.psychopy.org/t/randomly-selecting-and-grouping-rows-from-a-conditions-file/4502/7 "2018-05-17T13:40:53Z")

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Hi Michael,

Thanks for the reply! The suggestion worked (in that no errors occurred), however I found that this pulled exactly the same rows for each condition on every run, regardless of what seed value I provided ☹

SO I figured out a workaround. I did away with the seed values, and created a shuffled list of values corresponding to rows in my conditions file:

```auto
import random
row_vals = [0,1,2,3,4,5]
shuffle(row_vals)

```

I then assigned a range of indices in the (now shuffled) list to keys in a dictionary:

```auto
a = row_vals[0:2]
b = row_vals[4:6]
dict = {'cond_A':a,'cond_B':b}

```

and called a random key for each loop (note that in the builder I set the rows field of my two loops to $loop1 and $loop2)

```auto
x = random.choice(dict.keys())
loop1 = []
loop2 = []

loop1 = dict.get(x) 

if loop1 == dict.get('cond_A'):
    loop2 = dict.get('cond_B')
elif loop1 == dict.get('cond_B'):
    loop2 = dict.get('cond_A')

```

note that this can be tweaked to include a third condition (in this case, `cond_C`) using nested if-else function:

```auto
if loop1 == dict.get('cond_A'):
    if random.random()>0.5:
        loop2 = dict.get('cond_B')
    else:
        loop2 = dict.get('cond_C')
elif loop1 == dict.get('cond_B'):
    if random.random()>0.5:
        loop2 = dict.get('cond_A')
    else:
        loop2 = dict.get('cond_C')
elif loop1 == dict.get('cond_C'):
    if random.random()>0.5:
        loop2 = dict.get('cond_A')
    else:
        loop2 = dict.get('cond_B')

```