Data manipulation with aggregate

try this:

myData = data.frame(Name = c('a', 'a', 'b', 'b'), length = c(1,2,3,4), type

+ = c('x','x','y','z'))

result <- do.call(rbind, lapply(split(myData, myData$Name), function(.name){

+ data.frame(Name = .name$Name[1L]
+ , length = mean(.name$length)
+ , type = if (all(.name$type[1L] == .name$type)) .name$type[1L] else NA
+ )
+ })
+ )

result

Name length type
a    a    1.5    x
b    b    3.5 <NA>

Hi everyone.

I have these data :

myData = data.frame(Name = c('a', 'a', 'b', 'b'), length = c(1,2,3,4), type
= c('x','x','y','z'))

which gives me:

? Name length type
1 ? ?a ? ? ?1 ? ?x
2 ? ?a ? ? ?2 ? ?x
3 ? ?b ? ? ?3 ? ?y
4 ? ?b ? ? ?4 ? z

I would group (mean) this DF using 'Name' as grouping factor. However, I
have a field ('type') which is a string. I would like to use the unique
value of this field when possible (i.e. when all the 'type' values are the
same for each group) or replace with NA when 'type' has multiple values.

In fact, I would like to obtain this:

? Name length type
1 ? ?a ? ? ?1.5 ? ?x
2 ? ?b ? ? ?3.5 ? ?NA

For instance, I was using this command:

aggregate(list(myData$length, myData$type), list(myData$Name), FUN = mean)

But it can't deal with string data.

I hope I have been clear enough.

With regards,
Phil

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______________________________________________
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Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

Hi,

Try this:
myData = data.frame(Name = c('a', 'a', 'b', 'b'), length = c(1,2,3,4), type= c('x','x','y','z'))

z<-aggregate(length~Name,myData,mean)
z1<-aggregate(length~type,myData,mean)
merge(z,merge(z,z1),all=TRUE)
? Name length type
1??? a??? 1.5??? x
2??? b??? 3.5 <NA>

A.K.




----- Original Message -----
From: Filoche <pmassicotte at hotmail.com>
To: r-help at r-project.org
Cc: 
Sent: Tuesday, July 3, 2012 12:04 PM
Subject: [R] Data manipulation with aggregate

Hi everyone.

I have these data :

myData = data.frame(Name = c('a', 'a', 'b', 'b'), length = c(1,2,3,4), type
= c('x','x','y','z'))

which gives me:

? Name length type
1? ? a? ? ? 1? ? x
2? ? a? ? ? 2? ? x
3? ? b? ? ? 3? ? y
4? ? b? ? ? 4?  z

I would group (mean) this DF using 'Name' as grouping factor. However, I
have a field ('type') which is a string. I would like to use the unique
value of this field when possible (i.e. when all the 'type' values are the
same for each group) or replace with NA when 'type' has multiple values.

In fact, I would like to obtain this:

? Name length type
1? ? a? ? ? 1.5? ? x
2? ? b? ? ? 3.5? ? NA

For instance, I was using this command:

aggregate(list(myData$length, myData$type), list(myData$Name), FUN = mean)

But it can't deal with string data.

I hope I have been clear enough.

With regards,
Phil

--
View this message in context: http://r.789695.n4.nabble.com/Data-manipulation-with-aggregate-tp4635298.html
Sent from the R help mailing list archive at Nabble.com.

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.