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if statement with null values?

Solved!
GSung
Level 2

I have the below table (the left four columns) and would like to create a new column (called "Differences" as per below table), that is rounded to 3 decimal places

What If Statement can I use ?

I tried Round(if(Col1>0,Database-Col1,Database-Col2),3) ; but it did not work

CategoryDatabaseCol1Col2Differences
ABC-0.0018-0.0018 0.000
XYZ4.49423 4.4942318540.000
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1 Solution
tgb417
Neuron
Neuron

@GSung 

You could use a visual recipe step to "fold multiple columns" (unpivot) these columns (In your case Col1 & Col2).  (Particularly if there are actually more columns in your real dataset that will actually need to be evaluated in order to be successful.)  This will create a table that sort of looks like this.

Catagory Database
Col_NameValue
ABC-0.0018
Col1-0.0018
XYZ4.49423
Col 2 4.494231854

 

From here if there are actually multiple columns that might appear Col1, Col 2, Col 3, Col 4 you need to use a Group by a recipe to come up with an aggregate.  Or you are going to do multiple calculations for each category.

However, if there are just two columns and there is only ever one column filled.  You could do your calculation simply in a formula step from the data above.

Once this stage is done you could choose to drop the Col_Name Colum in the dataset above.  Or even unfold the data back to the original shape.  Depends on what your actual data looks like.  Lots of opportunities here.  

--Tom

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6 Replies
Manuel
Dataiker
Dataiker

How about filling the empty values with zeroes, before the formula step?

If you click on the column name > More Actions > Fill Empty Rows with ...

Jurre
Level 3

The Coalesce-function would be my first choice here, possibly with an extra if-call to check if there are cases where both col1 and col2 have values. Using a temporary column might also be usefull as these combinations of functions can get confusing. "isNull"/"isNotNull" with != or == could do the trick aswell because 0 (zero) is not the same as Null. 

edit : i may have been a bit unclear above. Your if-condition checks whether or not a value is bigger than zero, but an empty (Null) value is not the same as zero so that will not work. "isNotNull(col1)" checks for empty values. 

The Coalesce-function returns the first non-Null value of a set of values you can specify. You'll find the description of this function under "String-functions" in the formulalanguage-helpsection (https://doc.dataiku.com/dss/8.0/advanced/formula.html). or press "help" -see picture- 

Hope this helps, sorry for the late response! 

 

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tgb417
Neuron
Neuron

@GSung 

You could use a visual recipe step to "fold multiple columns" (unpivot) these columns (In your case Col1 & Col2).  (Particularly if there are actually more columns in your real dataset that will actually need to be evaluated in order to be successful.)  This will create a table that sort of looks like this.

Catagory Database
Col_NameValue
ABC-0.0018
Col1-0.0018
XYZ4.49423
Col 2 4.494231854

 

From here if there are actually multiple columns that might appear Col1, Col 2, Col 3, Col 4 you need to use a Group by a recipe to come up with an aggregate.  Or you are going to do multiple calculations for each category.

However, if there are just two columns and there is only ever one column filled.  You could do your calculation simply in a formula step from the data above.

Once this stage is done you could choose to drop the Col_Name Colum in the dataset above.  Or even unfold the data back to the original shape.  Depends on what your actual data looks like.  Lots of opportunities here.  

--Tom

View solution in original post

Jurre
Level 3

Thank you very much for adding your view on this Tom! It turns out that what you describe is a more efficient solution to a problem i faced a while ago with those multiple columns (a lot of them actually).

Life gets easier with neurons around 😉 Would be funny if Dataiku-staff introduced synapses aswell! 

 

 

MichaelG
Community Manager
Community Manager

Hey @Jurre - glad you managed to get a great solution!

I suppose the community itself would be the synapses right? Connecting neurons with other neurons (and of course all of our other users!)

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Jurre
Level 3

Spot on @MichaelG !   With data and ideas as the neurotransmitters 🙂

The funny -and wonderfull- thing is that it was not my question in the first place, i just tried to  help @GSung . @tgb417 stepped in with his take on it what happened to be a great idea which i can use for a completely different -but related- problem. Big smiles all over the place, i can assure you that!

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