RE: which() Function in SystemML

[Baeriswyl Kuno (IT-SWE-CC1-JV6)]

Hallo Berthold, Niketan,
Thanks for your helpful answers.

Finally, I've done following implementations:

#### which with for loop

A = matrix("1 3 5 2 4", rows=5, cols=1)

which = function (matrix[double] A) return (matrix[double] R) {
  R = matrix(0, 0, 1);
  n = nrow(A)
  for( i in 1:n ) {
    if(as.scalar(A[i,1]) > 0) {
        R = rbind(R, matrix(as.integer(i), 1, 1))
    }
  }
}

A2 = A>2
R = which(A2)


#### which with replace (Thanks to Niketan, I've understood the removeEmpty 
syntax ,finally )
A = matrix("1 3 5 2 4", rows=5, cols=1)

which = function (matrix[double] A) return (matrix[double] R) {
  R = removeEmpty(target=A*seq(1, nrow(A)), margin="rows") 
}

C = A>2
R = which(C)


#### is.na 
A =  matrix("1 3 5 0 4", rows=5, cols=1)
A[3,1] = A[3,1]/0

is_na = function (matrix[double] A) return (matrix[double] R) {
 R = A == 1/0
}

R = is_na(A)

Kuno


-----Original Message-----
From: Berthold Reinwald [mailto:reinw...@us.ibm.com] 
Sent: Samstag, 7. Juli 2018 02:12
To: dev@systemml.apache.org
Subject: Re: which() Function in SystemML

You may also look at example 2 "Replace NaN with mode" in our "DML Tips and 
Tricks" examples notebook. Will add a which() example shortly.

https://github.com/apache/systemml/raw/master/samples/jupyter-notebooks/DML%20Tips%20and%20Tricks%20(aka%20Fun%20With%20DML).ipynb


Regards,
Berthold Reinwald
IBM Almaden Research Center
office: (408) 927 2208; T/L: 457 2208
e-mail: reinw...@us.ibm.com



From:   "Niketan Pansare" <npan...@us.ibm.com>
To:     dev@systemml.apache.org
Date:   07/05/2018 10:26 AM
Subject:        Re: which() Function in SystemML



Hi Kuno,

Thanks for trying out SystemML. One way to implement your logic in SystemML is 
as follows:
X = matrix("1 4 -99 2 5 -99", rows=6, cols=1) Y = removeEmpty(target=(X > 
2)*seq(1, nrow(X)), margin="rows") print("\nIndexes:\n" + toString(Y))

For handling NAs, you can replace NAs by certain value (in this case -99 or one 
of the builtin constants, i.e. Inf or NaN ... see 
https://github.com/apache/systemml/blob/master/src/test/scripts/org/apache/sysml/api/mlcontext/builtin-constants-test.dml
) using the "na.strings" parameter of the transform builtin function ( 
http://apache.github.io/systemml/dml-language-reference.html#transforming-frames
). 

Hope this helps.

Regards,

Niketan Pansare
IBM Almaden Research Center
E-mail: npansar At us.ibm.com
http://researcher.watson.ibm.com/researcher/view.php?person=us-npansar

"Baeriswyl Kuno (IT-SWE-CC1-JV6)" ---07/05/2018 05:29:53 AM---Hello, I'm a 
developer want to use SystemMl for running R-Code from our business people on a 
Spark c

From: "Baeriswyl Kuno (IT-SWE-CC1-JV6)" <kuno.baeris...@sbb.ch>
To: "dev@systemml.apache.org" <dev@systemml.apache.org>
Date: 07/05/2018 05:29 AM
Subject: which() Function in SystemML



Hello,

I'm a developer want to use SystemMl for running R-Code from our business 
people on a Spark cluster.

I've studied http://apache.github.io/systemml/dml-language-reference , however, 
haven't found a implementation of the R function "which" or any alternative 
functionality. Has anyone an idea how I could

# Given
v = c(1,4,NA,2, 5, NA)

# Expect indexes where value meets condition =  int[] 2 5
v2 = which(v>2)

# Expect indexes where is.na returns TRUE =   int[] 3 6
v3 = which(is.na(v))

I've already considered the functions replace() and removeEmpty(), but they 
don't exactly meets my needs.

Thanks a lot in advance
Kuno