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Equivalent of MySQL "COALESCE"?

Contributor II greg
Contributor II

Equivalent of MySQL "COALESCE"?

Hi Community

I'm wondering if in rapidminer's formulas there is an equivalent of the command "coalesce" in mysql? Thats is a command which, given a list of parameters, returns the first non-null.

Example:

    DataFromSource1 = null
    DataFromSource2 = "foo"

coalesce(DataFromSource1, DatafromSource2, "default") would give "foo".

TIA

greg
2 REPLIES
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RM Staff
RM Staff

Re: Equivalent of MySQL "COALESCE"?

You can still use this function in SQL scripts, and insert SQL codes into RapidMiner for in-database SQL execution. (need “Read Database” or “Execute SQL” operators)

 

In rapidminer you can combine several operators for the same operation. For example, “Filter Examples” to remove the missing values (NULL), and then “Filter Example Range” to pick the 1st element.

 

I am attaching the example process here. Let me know if you have further questions.Filter Missing Values (Null).png

Community Manager Community Manager
Community Manager

Re: Equivalent of MySQL "COALESCE"?

Example with the Labor-Negotiations dataset and Generate Attributes:

 

if(missing([wage-inc-2nd]), -1, [wage-inc-2nd])

 

Or even:

 

if(missing([wage-inc-2nd]),
  if(missing([wage-inc-3rd]), -2,
    [wage-inc-3rd]),
  [wage-inc-2nd])

 

Not as clean as coalesce() but not bad either.

 

Regards,

 

Balázs

--
Balázs Bárány
Data Scientist, Vienna
https://datascientist.at
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