On Wednesday, September 19, 2012, Jul_biologyGrad wrote:
> Thanks everyone for the help! I pulled together a bunch of your suggestions
> to get the result that I needed. I'm posting my final code below. Probably
> not the most efficient way of doing things but gets the job done in a way
> that a n
Thanks everyone for the help! I pulled together a bunch of your suggestions
to get the result that I needed. I'm posting my final code below. Probably
not the most efficient way of doing things but gets the job done in a way
that a newbie can understand!
##Here again is the example dataset
Sample
e
wdunlap tibco.com
> -Original Message-
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of arun
> Sent: Monday, September 17, 2012 8:12 PM
> To: Julie Lee-Yaw
> Cc: R help
> Subject: Re: [R] help with calculation from dataf
On Sep 17, 2012, at 7:28 PM, arun wrote:
> HI,
> Try this:
> mydata$Gain<-rep(tapply(mydata$Mass,mydata$Sample,FUN=function(x)
> (x[3]-x[2])),each=length(unique(mydata$Sample)))
> mydata
> # Sample Time Mass Gain
> #1 11 3.0 0.3
> #2 12 3.1 0.3
> #3 13 3.4 0.3
HI,
Modified version of my earlier solution:
res1<-tapply(mydata$Mass,mydata$Sample,FUN=function(x) (x[3]-x[2]))
res2<-data.frame(Sample=names(res1),Gain2_3=res1)
merge(mydata,res2)
#Sample Time Mass Gain2_3
#1 1 1 3.0 0.3
#2 1 2 3.1 0.3
#3 1 3 3.4 0.3
#4
HI,
Try this:
mydata$Gain<-rep(tapply(mydata$Mass,mydata$Sample,FUN=function(x)
(x[3]-x[2])),each=length(unique(mydata$Sample)))
mydata
# Sample Time Mass Gain
#1 1 1 3.0 0.3
#2 1 2 3.1 0.3
#3 1 3 3.4 0.3
#4 2 1 4.0 0.1
#5 2 2 4.3 0.1
#6 2
Or diff(x[2:3])
Rui Barradas
Em 18-09-2012 01:05, David Winsemius escreveu:
On Sep 17, 2012, at 5:00 PM, David Winsemius wrote:
On Sep 17, 2012, at 4:15 PM, Julie Lee-Yaw wrote:
Hi
I have a dataframe similar to:
Sample<-c(1,1,1,2,2,2,3,3,3)
Time<-c(1,2,3,1,2,3,1,2,3)
Mass<-c(3,3.1,3.4,4,4
On Sep 17, 2012, at 5:00 PM, David Winsemius wrote:
>
> On Sep 17, 2012, at 4:15 PM, Julie Lee-Yaw wrote:
>
>> Hi
>>
>> I have a dataframe similar to:
>>
>>> Sample<-c(1,1,1,2,2,2,3,3,3)
>>
>>> Time<-c(1,2,3,1,2,3,1,2,3)
>>
>>> Mass<-c(3,3.1,3.4,4,4.3,4.4,3,3.2,3.5)
>>
>>> mydata<-as.data
On Sep 17, 2012, at 4:15 PM, Julie Lee-Yaw wrote:
> Hi
>
> I have a dataframe similar to:
>
>> Sample<-c(1,1,1,2,2,2,3,3,3)
>
>> Time<-c(1,2,3,1,2,3,1,2,3)
>
>> Mass<-c(3,3.1,3.4,4,4.3,4.4,3,3.2,3.5)
>
>> mydata<-as.data.frame(cbind(Sample,Time,Mass))
>
Please tell me where you learned tha
Hello,
Try the following.
sp <- split(mydata, mydata$Sample)
do.call(rbind, lapply(sp, function(x){x$Gain <- x$Mass[3] - x$Mass[2]; x}))
Hope this helps,
Rui Barradas
Em 18-09-2012 00:15, Julie Lee-Yaw escreveu:
> Hi
>
> I have a dataframe similar to:
>
>> Sample<-c(1,1,1,2,2,2,3,3,3)
>> Time<-
Julie -
Since the apply functions operate on one row at a time, they
can't do what you want. I think the easiest way to solve your
problem is to reshape the data set, and merge it back with the
original:
dd = data.frame(Sample=c(1,1,1,2,2,2,3,3,3),
+ Time=c(1,2,3,1,2,3,1,
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