"Loop Attributes - Expression Evaluation Error"

1705410G

I'm using 2 separate Loop Attributes Operator, each containing a Generate Attribute Operator.

Attribute Name(Inside Generate Attribute) for both Loop Attributes Operator: %{loop_attribute}


However, this error popped out. 
Expression Evaluation Error: The function 'eval' failed to parse the subexpression '203_10'. Cause: token recognition error at '_'  .
Initially, I thought that by removing the underscore '_' will solve it. But no matter what I did to rename it using the Rename by Replacing operator, it doesn't work. Same error comes up.



Sometimes, the Not Enough Iterations Error  pops up as well. I'm confused when I have set the Loop Attribute to subset and have selected the necessary attributes. 

Regards,
AY

David_A

Hi,

the problem here is how macros are parsed.
In your case, first %{loop_attribute} is replaced with the attribute name, this is "2_speed". Then the eval() function tries to make sense of that string as a number or mathematical expression, what fails.

In that case you need to use the seldom used #{loot_attribute} syntax. This returns the value corresponding to that attribute name.

@mschmitz has described it nicely in this posting:
https://community.rapidminer.com/discussion/50538/how-to-use-macros

And congratulations, you are now in the higher echelons of macro handling 

Best,
David

lionelderkrikor

Hi @1705410G,

Can you try to define attribute name as %{loop_attribute} (or something like %{loop_attribute}_bis if you don't want that your initial attributes are removed) instead of #{loop_attribute} :  



Hope it helps,

Regards,

Lionel

David_A

Hi,

the problem here is how macros are parsed.
In your case, first %{loop_attribute} is replaced with the attribute name, this is "2_speed". Then the eval() function tries to make sense of that string as a number or mathematical expression, what fails.

In that case you need to use the seldom used #{loot_attribute} syntax. This returns the value corresponding to that attribute name.

@mschmitz has described it nicely in this posting:
https://community.rapidminer.com/discussion/50538/how-to-use-macros

And congratulations, you are now in the higher echelons of macro handling 

Best,
David

1705410G

HI David_A 

#{loop_attribute} syntax worked!! Thank you!! But the results seems wrong

As mentioned above, i'm using 2 separate Loop Attributes operator.

Attribute filter type is set to subset with about 40 different attributes selected in each Loop Attributes operator. 
 

However, there's only 1 column of results produced by the first loop and second loop (Shown below). Does it means that both Loop Attributes only loop once?  
  


My question is how can I allow the 2 different loops to loop for all selected attributes?
So I should be able to get 80 new columns in total. 40 for the first loop function and 40 for the second loop function.  

P.S. How do I get the loop attributes to use back the same name rather than #{loop_attribute} since I have 40 over attributes in each Loop Attribute operator?


Thank you!! 

Regards,
AY

lionelderkrikor

Hi @1705410G,

Can you try to define attribute name as %{loop_attribute} (or something like %{loop_attribute}_bis if you don't want that your initial attributes are removed) instead of #{loop_attribute} :  



Hope it helps,

Regards,

Lionel

1705410G

Hi 

It worked! Thank you so much to all that contributed!

kypexin

In that case you need to use the seldom used #{loot_attribute} syntax. This returns the value corresponding to that attribute name.

@David_A -- thanks for that secret knowledge, it took me an hour of my life to struggle with Loop Attributes before I have found this solution on the forum!

PS one more proof how really useful and helpful RM community can be! MAGIC!

MartinLiebig

@kypexin ,

i am quite close to write a getValueOf(String attribute) function and add it to the expression parser. I got the feeling that this would fix this hazzle.

BR,

Martin

kypexin

@mschmitz -- would be great!

'#{macro}' notation is basically okay (if you know about it of course ), but having getValueOf(String attribute) would simplify the process structure in some cases.