Excellent.  I should have thought of the with statement, since it’s kind of a universal coding method.  Have a good wknd. BNC

From: arun kirshna [via R] [mailto:ml-node+s789695n4671365h27@n4.nabble.com]
Sent: Thursday, July 11, 2013 4:55 PM
To: Crombie, Burnette N
Subject: Re: create new matrix from user-defined function

Hi BNC,
No problem.
You could also use ?with()

data.frame(MW_EEsDue_ERRORS=with(dat3,A_CaseID[D_MW_EEsDueTotal!=rowSums(cbind(B_MW_EEsDue1,C_MW_EEsDue2))]))
#  MW_EEsDue_ERRORS
#1             1882
#2             1884
#3             1885
A.K.



----- Original Message -----
From: "Crombie, Burnette N" <[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=0>>
To: arun <[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=1>>
Cc: R help <[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=2>>
Sent: Thursday, July 11, 2013 4:40 PM
Subject: RE: [R] create new matrix from user-defined function

You understood me perfectly, and I agree is it easier to index using numbers than names.  I'm just afraid if my dataset gets too big I'll mess up which index numbers I'm supposed to be using.  "data.table()" looks very useful and a good way to approach the issue.  Thanks.  I really appreciate your (everyone's) help.  BNC

-----Original Message-----
From: arun [mailto:[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=3>]
Sent: Thursday, July 11, 2013 4:29 PM
To: Crombie, Burnette N
Cc: R help
Subject: Re: [R] create new matrix from user-defined function

Hi,
Not sure I understand you correctly.
I found it easier to index using number than replace it by lengthy column names.
You could do it similar to the one below.

matNew<-matrix(dat3[rowSums(dat3[c("B_MW_EEsDue1","C_MW_EEsDue2")])!=dat3["D_MW_EEsDueTotal"],1],ncol=1,dimnames=list(NULL,"MW_EEsDue_ERRORS"))

 matNew
#     MW_EEsDue_ERRORS
#[1,]             1882
#[2,]             1884
#[3,]             1885

If you have very large dataset, you could also check ?data.table().


library(data.table)
dt3<- data.table(dat3)
dtNew<-subset(dt3[D_MW_EEsDueTotal!=B_MW_EEsDue1+C_MW_EEsDue2],select=1)
 dtNew
#   A_CaseID
#1:     1882
#2:     1884
#3:     1885


#Some speed comparisons:
set.seed(1254)
datTest<- data.frame(A=sample(1000:15000,1e7,replace=TRUE),B= sample(1:10,1e7,replace=TRUE),C=sample(5:15,1e7,replace=TRUE),D=sample(5:25,1e7,replace=TRUE))

system.time(res1<- data.frame(MW_EEsDue_ERRORS=datTest[datTest[[4]] != datTest[[2]]+datTest[[3]],][[1]]))
# user  system elapsed
#  2.256   0.000   2.145

system.time(mat1<-matrix(datTest[rowSums(datTest[,2:3])!=datTest[,4],1],ncol=1,dimnames=list(NULL,"MW_EEsDue_ERRORS")))
 #  user  system elapsed
 # 0.756   0.088   0.849

system.time(res2<- data.frame(MW_EEsDue_ERRORS=datTest[addmargins(as.matrix(datTest[,2:3]),2)[,3]!=datTest[,4],1]))
#   user  system elapsed
#115.740   0.000 105.778

dtTest<- data.table(datTest)
system.time(res3<- subset(dtTest[D!=B+C],select=1))
 # user  system elapsed
 # 0.508   0.000   0.477

identical(res1,res2)
#[1] TRUE
setnames(res3,"A","MW_EEsDue_ERRORS")
 identical(res1,as.data.frame(res3))
#[1] TRUE
A.K.




----- Original Message -----
From: bcrombie <[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=4>>
To: [hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=5>
Cc:
Sent: Thursday, July 11, 2013 3:54 PM
Subject: Re: [R] create new matrix from user-defined function

Dan and Arun, thank you very much for your replies.  They are both very helpful and I love to get different versions of an answer so I can learn more R code.  You both used indexing to refer to the columns needed in the function, but since my real data frame will be much larger I'm assuming I can replace the index numbers with the names of the columns in quotes instead?   I'll try this on my own if you're busy with other forum questions.  Thanks, again.

From: Nordlund, Dan (DSHS/RDA) [via R] [mailto:[hidden email]</user/SendEmail.jtp?type=node&node=4671365&i=6>]
Sent: Wednesday, July 10, 2013 5:46 PM
To: Crombie, Burnette N
Subject: Re: create new matrix from user-defined function

> -----Original Message-----
> From: [hidden email]</user/SendEmail.jtp?type=node&node=4671267&i=0>
> [mailto:r-help-bounces@r-
> project.org<mailto:r-help-bounces@r-%20%0b%3e%20project.org><mailto:r-help-bounces@r-%20%0b%3e%20project.org%3cmailto:r-help-bounces@r-%20%0b%3e%20project.org%3e>] On
> Behalf Of bcrombie
> Sent: Wednesday, July 10, 2013 12:19 PM
> To: [hidden email]</user/SendEmail.jtp?type=node&node=4671267&i=1>
> Subject: [R] create new matrix from user-defined function
>
> #Let's say I have the following data set:
>
> dat3 = data.frame(A_CaseID = c(1881, 1882, 1883, 1884, 1885),
>                   B_MW_EEsDue1 = c(2, 2, 1, 4, 6),
>                   C_MW_EEsDue2 = c(5, 5, 4, 1, 6),
>                   D_MW_EEsDueTotal = c(7, 9, 5, 6, 112))
> dat3
> # A_CaseID B_MW_EEsDue1 C_MW_EEsDue2 D_MW_EEsDueTotal  # 1     1881
>2            5                7  # 2     1882            2            5
>9  # 3     1883            1            4                5  # 4
>1884            4            1                6  # 5     1885
>6            6              112
>
> # I want to:
> #CREATE A NEW 1-COLUMN MATRIX (of unknown #rows) LISTING ONLY "A"'s
> WHERE "D != B + C"
> #THIS COLUMN CAN BE LABELED "MW_EEsDue_ERRORS", and output for this
> example should be:
>
> # MW_EEsDue_ERRORS
> # 1 1882
> # 2 1884
> # 3 1885
>
> #What is the best way to do this?  Thanks for your time.  BNC
>
>

Here is one option, there are many others.  Only you can decide what is "best".

data.frame(MW_EEsDue_ERRORS=dat3[dat3[[4]] != dat3[[2]]+dat3[[3]],][[1]])


Hope this is helpful,

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division Olympia, WA 98504-5204

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