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plurals

PO
primarykey
Id
6955240
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
CreationDate
2011-08-05T11:00:48.603
FavoriteCount
0
LastActivityDate
2011-08-05T13:12:18.747
LastEditDate
2011-08-05T13:12:18.747
LastEditorUserId
636656
OwnerUserId
636656
ParentId
6955128
PostTypeId
2
Score
3
ViewCount
0
LastEditorDisplayName
text
Body
Looks like you have an environment problem. Global assignment fixes the problem, but at the cost of one's soul: <pre><code>library(plyr) a = c(1,2,3,4) b = c(0,0,1,1) c = c(5,6,7,8) d.f = data.frame(a,b,c) sv = c("b") ColName = "a" ddply(d.f, sv, summarize, Ave = mean(eval(parse(text=ColName)), na.rm=TRUE) ) myFunction <- function(x, y){ NewColName <<- "a" z = ddply(x, y, summarize, Ave = mean(eval(parse(text=NewColName)), na.rm=TRUE) ) return(z) } myFunction(x=d.f,y=sv) </code></pre> <code>eval</code> is looking in parent.frame(1). So if you instead define NewColName outside MyFunction it should work: <pre><code>rm(NewColName) NewColName <- "a" myFunction <- function(x, y){ z = ddply(x, y, summarize, Ave = mean(eval(parse(text=NewColName)), na.rm=TRUE) ) return(z) } myFunction(x=d.f,y=sv) </code></pre> By using <code>get</code> to pull out my.parse from the earlier environment, we can come much closer, but still have to pass curenv as a global: <pre><code>myFunction <- function(x, y){ NewColName <- "a" my.parse <- parse(text=NewColName) print(my.parse) curenv <<- environment() print(curenv) z = ddply(x, y, summarize, Ave = mean( eval( get("my.parse" , envir=curenv ) ), na.rm=TRUE) ) return(z) } > myFunction(x=d.f,y=sv) expression(a) <environment: 0x0275a9b4> b Ave 1 0 1.5 2 1 3.5 </code></pre> I suspect that <code>ddply</code> is evaluating in the .GlobalEnv already, which is why all of the <code>parent.frame()</code> and <code>sys.frame()</code> strategies I tried failed.
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1. This table or related slice is empty.
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1. POObject not found error with ddply inside a function
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1. PTAnswer
UserLastEditorUserId
1. USAri B. Friedman
UserOwnerUserId
1. USAri B. Friedman
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2. VO
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CommentsPostId
1. COI suspect the solution might require the @Hadley function :-)
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 USAri B. Friedman
2. COGreat effort in trying all these. Group head banging is always appreciated...... I'll keep my soul
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