THANKS, but I have one issue and one question.
For some reason the "secondstrongest" value for row 3 and 6 are incorrect (they
are the strongest) the remaining 10 are correct??
These data are being used to track radio-tagged birds, they are from automated
radio telemetry receivers. I will applying the following formula
diff <- ((strongest- secondstrongest)/100)
bearingdiff <-30-(-0.0624*(diff**2))-(2.8346*diff)
Then the bearing diff is added to strongestantenna (value0 = 0degrees) if the
secondstrongestatenna is greater (eg value0 and value60), or if the
secondstrongestantenna is smaller than the strongestantenna, then the
bearingdiff is substracted from the strongestantenna. The only exception is
that if value0 (0degrees) is strongest and value300(360degrees) is the
secondstrongestantenna then the bearing is 360-bearingdiff. Also the
strongestantenna and secondstrongestantenna have to be next to each other (e.g.
value0 with value60, value240 with value300, value0 with value300) or the
results should be NA. I have been trying to use a series of if,else statements
to produce these bearing, but all I am producing is errors. Any suggestion
would be appreciated.
Again THANKS for you efforts.
Mike
---- Original message ----
>Date: Fri, 23 Jul 2010 23:01:56 -0700
>From: Joshua Wiley <jwiley.ps...@gmail.com>
>Subject: Re: [R] Trouble retrieving the second largest value from each row of
>a data.frame
>To: mpw...@illinois.edu
>Cc: r-help@r-project.org
>
>Hi,
>
>Here is a little function that will do what you want and return a nice output:
>
>#Function To calculate top two values and return
>my.finder <- function(mydata) {
> my.fun <- function(data) {
> strongest <- which.max(data)
> secondstrongest <- which.max(data[-strongest])
> strongestantenna <- names(data)[strongest]
> secondstrongantenna <- names(data[-strongest])[secondstrongest]
> value <- matrix(c(data[strongest], data[secondstrongest],
> strongestantenna, secondstrongantenna), ncol =4)
> return(value)
> }
> dat <- apply(mydata, 1, my.fun)
> dat <- t(dat)
> dat <- as.data.frame(dat, stringsAsFactors = FALSE)
> colnames(dat) <- c("strongest", "secondstrongest",
> "strongestantenna", "secondstrongantenna")
> dat[ , "strongest"] <- as.numeric(dat[ , "strongest"])
> dat[ , "secondstrongest"] <- as.numeric(dat[ , "secondstrongest"])
> return(dat)
>}
>
>
>#Using your example data:
>
>yourdata <- structure(list(value0 = c(-13007L, -12838L, -12880L, -12805L,
>-12834L, -11068L, -12807L, -12770L, -12988L, -11779L), value60 = c(-11707L,
>-13210L, -11778L, -11653L, -13527L, -11698L, -14068L, -11665L,
>-11736L, -12873L), value120 = c(-11072L, -11176L, -11113L, -11071L,
>-11067L, -12430L, -11092L, -11061L, -11137L, -12973L), value180 = c(-12471L,
>-11799L, -12439L, -12385L, -11638L, -12430L, -11709L, -12373L,
>-12570L, -12537L), value240 = c(-12838L, -13210L, -13089L, -11561L,
>-13527L, -12430L, -11607L, -11426L, -13467L, -12973L), value300 = c(-13357L,
>-13845L, -13880L, -13317L, -13873L, -12814L, -13025L, -12805L,
>-13739L, -11146L)), .Names = c("value0", "value60", "value120",
>"value180", "value240", "value300"), class = "data.frame", row.names = c("1",
>"2", "3", "4", "5", "6", "7", "8", "9", "10"))
>
>my.finder(yourdata) #and what you want is in a nicely labeled data frame
>
>#A potential problem is that it is not very efficient
>
>#Here is a test using a matrix of 100,000 rows
>#sampled from the same range as your data
>#with the same number of columns
>
>data.test <- matrix(
> sample(seq(min(yourdata),max(yourdata)), size = 500000, replace = TRUE),
> ncol = 5)
>
>system.time(my.finder(data.test))
>
>#On my system I get
>
>> system.time(my.finder(data.test))
> user system elapsed
> 2.89 0.00 2.89
>
>Hope that helps,
>
>Josh
>
>
>
>On Fri, Jul 23, 2010 at 6:20 PM, <mpw...@illinois.edu> wrote:
>> I have a data frame with a couple million lines and want to retrieve the
>> largest and second largest values in each row, along with the label of the
>> column these values are in. For example
>>
>> row 1
>> strongest=-11072
>> secondstrongest=-11707
>> strongestantenna=value120
>> secondstrongantenna=value60
>>
>> Below is the code I am using and a truncated data.frame. Retrieving the
>> largest value was easy, but I have been getting errors every way I have
>> tried to retrieve the second largest value. I have not even tried to
>> retrieve the labels for the value yet.
>>
>> Any help would be appreciated
>> Mike
>>
>>
>>> data<-data.frame(value0,value60,value120,value180,value240,value300)
>>> data
>> value0 value60 value120 value180 value240 value300
>> 1 -13007 -11707 -11072 -12471 -12838 -13357
>> 2 -12838 -13210 -11176 -11799 -13210 -13845
>> 3 -12880 -11778 -11113 -12439 -13089 -13880
>> 4 -12805 -11653 -11071 -12385 -11561 -13317
>> 5 -12834 -13527 -11067 -11638 -13527 -13873
>> 6 -11068 -11698 -12430 -12430 -12430 -12814
>> 7 -12807 -14068 -11092 -11709 -11607 -13025
>> 8 -12770 -11665 -11061 -12373 -11426 -12805
>> 9 -12988 -11736 -11137 -12570 -13467 -13739
>> 10 -11779 -12873 -12973 -12537 -12973 -11146
>>> #largest value in the row
>>> strongest<-apply(data,1,max)
>>>
>>>
>>> #second largest value in the row
>>> n<-function(data)(1/(min(1/(data[1,]-max(data[1,]))))+ (max(data[1,])))
>>> secondstrongest<-apply(data,1,n)
>> Error in data[1, ] : incorrect number of dimensions
>>>
>>
>> ______________________________________________
>> R-help@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.
>>
>
>
>
>--
>Joshua Wiley
>Ph.D. Student, Health Psychology
>University of California, Los Angeles
>http://www.joshuawiley.com/
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