Calculate Range

Hi

My R version is the current version as at 15 Nov 2013.

I have tried to calculate range using tapply() with FUN=range.
tapply() returns two fields, the ID field and a field of two text items one
is the maximum and the other is the minimum.
I take as the difference max - min, does R use a different term for range in
tapply?

I have also tried
aggregate() with Fun=range, with Fun=min and FUN=max
and they also gave problems.

What is the best route to calculate ranges for groups within a data frame.

Hi Scriptham,
It looks like you want to get the difference between the maximum and 
minimum values rather than the actual values. Define a function:

range_span<-function(x) return(diff(range(x)))

and use that as the FUN argument.

Jim

An approach using data tables:

###
library(data.table)
# dt: some data arranged by group
dt <- data.table(group=c(rep("a",5), rep("b",10), rep("c",15)), values=1:30)
# summarize by group
smry <- dt[,list(min=min(values), max=max(values), range=diff(range(values))), by="group"]
smry
###


-----Original Message-----
From: SCRIPTHAM [mailto:JML at CWAZY.CO.UK] 
Sent: Saturday, November 16, 2013 4:50 PM
To: r-help at r-project.org
Subject: [R] Calculate Range

Hi

My R version is the current version as at 15 Nov 2013.

I have tried to calculate range using tapply() with FUN=range.
tapply() returns two fields, the ID field and a field of two text items one is the maximum and the other is the minimum.
I take as the difference max - min, does R use a different term for range in tapply?

I have also tried
aggregate() with Fun=range, with Fun=min and FUN=max and they also gave problems.

What is the best route to calculate ranges for groups within a data frame.

Thanks.
Scriptham.






--
View this message in context: http://r.789695.n4.nabble.com/Calculate-Range-tp4680579.html
Sent from the R help mailing list archive at Nabble.com.

Hi,
You may also check:
library(psych)
library(plyr)
df1 <- data.frame(group=rep(letters[1:3],c(5,10,15)), values=1:30)
ddply(df1,.(group),mutate,Range=describe(values)$range) ##depends on how you wanted the output
#or
ddply(df1,.(group),summarise,Range=describe(values)$range)
#or
with(df1,describeBy(values,group,mat=TRUE))[,c("group1","range")]
A.K.

Hi

My R version is the current version as at 15 Nov 2013.

I have tried to calculate range using tapply() with FUN=range.
tapply() returns two fields, the ID field and a field of two text items one
is the maximum and the other is the minimum.
I take as the difference max - min, does R use a different term for range in
tapply?

I have also tried
aggregate() with Fun=range, with Fun=min and FUN=max 
and they also gave problems.

What is the best route to calculate ranges for groups within a data frame.

Thanks.
Scriptham.






--
View this message in context: http://r.789695.n4.nabble.com/Calculate-Range-tp4680579.html
Sent from the R help mailing list archive at Nabble.com.

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