[R] nested looping functions and dataframes

[Phil Spector]

Lanna -
    Here's one way:

makeframe = function(x){
    b = as.data.frame(as.matrix(table(x$Species,x$Species)))
    b = b[!(b$Var1 == b$Var2),-3]
    data.frame(Year=x$Year[1],Location=x$Location[1],b)
}

result = lapply(split(x,list(x$Year,x$Location)),makeframe)

result will be a list of data frames, one for each 
Year/Location combination.    You can find the data frame
for a particular Year/Location combination as

     Year = 1998
     Location = 'PIPE_7'
     result[[paste(Year,Location,sep='.')]]

Hope this helps.

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu


On Tue, 16 Mar 2010, Lanna Jin wrote:

>
> Hey All,
>
> So, I am confused how exactly to use nesting loop functions in R to spit out
> data frames.  I've managed to create a working function for my data set that
> generates a data frame for a given set of Year i and Location j; but how
> would I do it for all Years and Locations?
>
> Here is my working function:
>
> test<-function(i,j){
> a<-x[which(x$Year==i & x$Location==j),]
> b<-as.data.frame(as.matrix(table(a$Species,a$Species)))
> c<-b[-which(b$Var1==b$Var2),-3]
> c$Year<-i; c$Location<-j
> return(c)
> }
>
> Where, x is a dataframe that looks like the following:
>
>> head(x,n=20)
>   Year Location    Species
> 66 1998   PIPE_7      ACMI2
> 67 1998   PIPE_7      AMAR2
> 68 1998   PIPE_7      AMCA6
> 69 1998   PIPE_7       ANCY
> 70 1998   PIPE_7       ASVE
> 71 1998   PIPE_7       BOCU
> 72 1998   PIPE_7       CIFL
> 73 1998   PIPE_7      DAPU5
> 74 1998   PIPE_7 DICHANTHEL
> 75 1998   PIPE_7      GABO2
> 76 1998   PIPE_7      HEHE5
> 77 1998   PIPE_7       LIAS
> 78 1998   PIPE_7       LIPY
> 79 1998   PIPE_7      PAVI2
> 80 1998   PIPE_7       PHPI
> 81 1998   PIPE_7      PHVI5
> 82 1998   PIPE_7       RAPI
> 83 1998   PIPE_7      SOCA6
> 84 1998   PIPE_7      VIPE2
> 85 1998   PIPE_7       ZIAU
>
> and when feeding x into my function "test" with the parameters i = 1998 and
> j = "PIPE_7", I get the following dataframe, c:
>
>> head(test(1998,"PIPE_7"),n=20)
>         Var1  Var2 Year Location
> 2       AMAR2 ACMI2 1998   PIPE_7
> 3       AMCA6 ACMI2 1998   PIPE_7
> 4        ANCY ACMI2 1998   PIPE_7
> 5        ASVE ACMI2 1998   PIPE_7
> 6        BOCU ACMI2 1998   PIPE_7
> 7        CIFL ACMI2 1998   PIPE_7
> 8       DAPU5 ACMI2 1998   PIPE_7
> 9  DICHANTHEL ACMI2 1998   PIPE_7
> 10      GABO2 ACMI2 1998   PIPE_7
> 11      HEHE5 ACMI2 1998   PIPE_7
> 12       LIAS ACMI2 1998   PIPE_7
> 13       LIPY ACMI2 1998   PIPE_7
> 14      PAVI2 ACMI2 1998   PIPE_7
> 15       PHPI ACMI2 1998   PIPE_7
> 16      PHVI5 ACMI2 1998   PIPE_7
> 17       RAPI ACMI2 1998   PIPE_7
> 18      SOCA6 ACMI2 1998   PIPE_7
> 19      VIPE2 ACMI2 1998   PIPE_7
> 20       ZIAU ACMI2 1998   PIPE_7
> 21      ACMI2 AMAR2 1998   PIPE_7
>
>
> I have searched through the R-help archives for hints, which have not been
> successful in answering my question.  As a new user to R and programming
> languages, I truly appreciate your help and thank you for your patience.
>
> Thanks in advance for your response,
> Lanna Jin
>
> -----
> Lanna Jin
>
> lannajin at gmail.com
> 510-898-8525
> -- 
> View this message in context: http://n4.nabble.com/nested-looping-functions-and-dataframes-tp1595166p1595166.html
> Sent from the R help mailing list archive at Nabble.com.
>
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