[R] Trouble retrieving the second largest value from each row of a data.frame
David Winsemius
dwinsemius at comcast.net
Sun Jul 25 03:48:12 CEST 2010
On Jul 24, 2010, at 9:27 PM, David Winsemius wrote:
>
> On Jul 24, 2010, at 8:09 PM, David Winsemius wrote:
>
>>
>> On Jul 24, 2010, at 4:54 PM, <mpward at illinois.edu> wrote:
>>
>>> 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??
>>
>> In my run of Wiley's code I instead get identical values for rows
>> 2,5,6. Holtman's and my solutions did not suffer from that defect,
>> although mine suffered from my misreading of your request, thinking
>> that you wanted the top 3. The fix is trivial
>>>
>>> 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)
>>
>> vals <- c("value0", "value60", "value120", "value180", "value240",
>> "value300")
>> value.str2 <- (match(yourdata$secondstrongestantenna, vals)-1)*60
Had a misspelling ... rather:
match(yourdata$secondstrongantenna, vals)
>> value.str1 <- (match(yourdata$strongestantenna, vals)-1)*60
>> change.ind <- abs(match(yourdata, vals) - which(match(yourdata,
>> vals) )
>
> OOOPs should have been
>
> change.ind <- abs(match(yourdata, vals) - match(yourdata, vals) )
>
>
>>
>>>
>>> A) Then the bearing diff is added to strongestantenna (value0 =
>>> 0degrees) if the secondstrongestatenna is greater (eg value0 and
>>> value60),
>>
>>> B) or if the secondstrongestantenna is smaller than the
>>> strongestantenna,
>>> then the bearingdiff is substracted from the strongestantenna.
>
> yourdata$finalbearing <- with(yourdata, ifelse
> (value.str2>value.str1, bearingdiff+value.str1, value.str1-
> bearingdiff) )
>
>
>>
>>>
>>> C) The only exception is that if value0 (0degrees) is strongest
>>> and value300(360degrees) is the secondstrongestantenna then the
>>> bearing is 360-bearingdiff.
>>
>
> yourdata$finalbearing <- with(yourdata, ifelse (strongestantenna ==
> "value0" & secondstrongantenna == "value300", 360- bearingdiff,
> finalbearing) );
>
>
>>> D) Also the strongestantenna and secondstrongestantenna have to be
>>> next to each other (e.g. value0 with value60, value240 with
>>> value300, value0 with value300) or the results should be NA.
>>
>> After setting finalbearing with A, B, and C then:
>> yourdata$finalbearing <- with(yourdata, ifelse (
>> change.ind <5 & change.ind > 1 ,
>> NA, finalbearing) )
>
Better result with proper creation of value.str2:
yourdata
strongest secondstrongest strongestantenna secondstrongantenna
finalbearing
1 -11072 -11707 value120 value60
105.48359
2 -11176 -11799 value120 value180
134.76237
3 -11113 -11778 value120 value60
106.09061
4 -11071 -11561 value120
value240 NA
5 -11067 -11638 value120 value180
135.84893
6 -11068 -11698 value0 value60
14.61868
7 -11092 -11607 value120
value240 NA
8 -11061 -11426 value120
value240 NA
9 -11137 -11736 value120 value60
104.74034
10 -11146 -11779 value300 value0
285.44272
>>
>>> I have been trying to use a series of if,else statements to
>>> produce these bearing,
>
> ifelse is the correct construct for processing vectors
>
> --
> David.
>>> 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.psych at gmail.com>
>>>> Subject: Re: [R] Trouble retrieving the second largest value from
>>>> each row of a data.frame
>>>> To: mpward at illinois.edu
>>>> Cc: r-help at 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, <mpward at 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 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.
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Joshua Wiley
>>>> Ph.D. Student, Health Psychology
>>>> University of California, Los Angeles
>>>> http://www.joshuawiley.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.
>>
>> ______________________________________________
>> 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.
>
> ______________________________________________
> 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.
More information about the R-help
mailing list