On Feb 8, 2012, at 6:29 PM, Johannes Radinger wrote:
Am 08.02.2012 um 23:47 schrieb David Winsemius:
On Feb 8, 2012, at 5:06 PM, Johannes Radinger wrote:
Am 08.02.2012 um 22:19 schrieb David Winsemius:
On Feb 8, 2012, at 4:11 PM, Johannes Radinger wrote:
Hi,
I want to split a dataframe based on a grouping variable (in one
column). The resulting new
dataframes should be stored in a new variable. I tried to split
the dataframe using split() and
to store it using a FOR loop, but thats not working so far:
df <- data.frame(A=c("A1","A1","A2","A2"),B=seq(1:4))
Fsplit <- function(x,y){
ls <- split(x,f=x$y)
for (i in names(ls)){
i <- ls$i
}
}
Fsplit(df,A) #1st argument is dataframe to split, 2nd argument
grouping variable
It appears you want the name of the levels of df$A to be the
names of separate variables in the global environment. If that is
correct, then see the FAQ. I'm not sure which one it is among the
Miscellaneous section, but you should be looking of the one that
tells you how to construct a named variable.
Your hint with the global environment brought me on track. It
seems that I this task can be done with list2env() although there
is still a problem with my function. How
can I parse the name of the dataframe and the column name in the
function...
df <- data.frame(A=c("A1","A1","A2","A2"),B=seq(1:4))
Fsplit <- function(x,y){
ls <- split(x,f=x$y)
list2env(ls,envir = .GlobalEnv)
}
Fsplit(df,A)
I still have not figured out what you really want to do. The simple
answer to what you ask for in your written request is simply:
dfvar <- split(df, df$A)
So what is it about that result that is not useful for your (as yet
unstated) destination?
> split(df, df$A)
$A1
A B
1 A1 1
2 A1 2
$A2
A B
3 A2 3
4 A2 4
Sorry for not being clear enough, and your are
right as "split(df, df$A)" is what I want. Additionally I want to
store afterwards
the single objects of the list in new dataframes
where variable name = name of list object (which can be done with
list2env()).
Is that clear enough so far?
If you want to put that list in an environment, it's fine with me. Or
you can access it from the split-object-list-of-dataframes, dfvar,
using with()
> with(dfvar, A1)
A B
1 A1 1
2 A1 2
Note: with() does not work well inside other functions
For programming purposes this might be safer..
> new.env <- environment()
> list2env(dfvar, new.env)
<environment: R_GlobalEnv>
> new.env$A1
A B
1 A1 1
2 A1 2
What I want exactly is to express that two operations (split,
list2env) within
one function. I need the function for other tasks in R.
/johannes
/johannes
Or:
? assign
--
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
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