Displaying 20 results from an estimated 6000 matches similar to: "Help in splitting a list"
2011 Apr 03
1
Help in splitting ists into sub-lists
Dear List,
Let's say I have a list whose components are 2 matrices (as exemplified in
the "mylist" object below). I'd like to create a list with components being
4 matrices based on an logical index vector. is there a way to simplify what
I'm doing to obtain the results in "mylist2"? I'd like something that would
work on an arbitrary number of elements in
2013 Mar 13
2
holding argument(s) fixed within lapply
|Hello,
Given a function with several arguments, I would like to perform an
lapply (or equivalent) while holding one or more arguments fixed to some
common value, and I would like to do it in as elegant a fashion as
possible, without resorting to wrapping a separate wrapper for the
function if possible. Moreover I would also like it to work in cases
where one or more arguments to the original
2010 Oct 28
1
Merging nested lists
Hello All,
I have multiple "list of lists" in the form of
Mylist1[[N]][[K]]$Name_i,
with N=1..6, K=1..3, and i=1..7. Each Name_i is a matrix. I have 30 of these objects Mylist1, Mylist2, ...
I would like to merge these lists by each Name_i using rbind, but I couldn't figure out how to do it. What I want at the end is a single "list of lists", again in the form of
2010 Sep 09
0
Fast / dependable way to "stack together" data frames from a list
Hi, everybody:
I asked about this in r-help last week and promised
a summary of answers. Special thanks to the folks
that helped me understand do.call and pointed me
toward plyr.
We face this problem all the time. A procedure
generates a list of data frames. How to stack them
together?
The short answer is that the plyr package's rbind.fill
method is probably the fastest method that is not
2010 Feb 19
4
Accessing values of a matrix
hello all,
thank you for taking the time
I have a matrix A that have column names (let say n columns), I want to
reduce the matrix to have just a few of those column (p colums, this is
trivial), but for the lines I want only the lines such that A(i,J) is part
of a list (J is fixed and known)
I am sure it is very easy but I don't find it (I tryed which but it doesn't
seem to work)
Surely
2010 Sep 26
4
Problem with unlist
Hello I want to unlist the attached element getting only the first element
in each element of the list. The last element of the list looks as this:
[[5065]]
[[5065]]$Pluv3Meses
[1] 274.4
[[5065]]$PluvMesesMedio
[1] 378.2667
[[5065]]$Pluv2UltimosMeses
[1] 23.33333
So I would like to get for each element of the list the element called
Pluv3Meses. The whole list has 5065 elements but when I try to
2008 Mar 13
3
Splitting a set of vectors in a list
I have a set of character vectors of uneven length
that I have stored in a list. I can easily enough get
any column of them using lapply but what I want is to
be able to create a matrix of them. Other than some
kind of brute force looping approach I have drawn a
blank.
Would somebody please suggest something? Thanks
Example.
mylist <- list(aa=c("cat","peach" ),
2013 Mar 07
3
rbind a list of matrices
I have a large list of matrices and a vector that identifies the desired
matrices that I would like to rbind. However, I am stuck on how to get
this to work. I have written some code below to illustrate my problem:
# 3 simple matrices
a<-matrix(1:9,3,3)
b<-matrix(10:18,3,3)
c<-matrix(19:27,3,3)
#this is the type of list of matrices I am dealing with
2015 May 04
2
Define replacement functions
Hello
I tried to define replacement functions for the class "mylist". When I test them in an active R session, they work -- however, when I put them into a package, they don't. Why and how to fix?
make_my_list <- function( x, y ) {
return(structure(list(x, y, class="mylist")))
}
mylist <- make_my_list(1:4, letters[3:7])
mylist
mylist[['x']] <- 4:6
2009 Oct 25
3
NULL elements in lists ... a nightmare
I can define a list containing NULL elements:
> myList <- list("aaa",NULL,TRUE)
> names(myList) <- c("first","second","third")
> myList
$first
[1] "aaa"
$second
NULL
$third
[1] TRUE
> length(myList)
[1] 3
However, if I assign NULL to any of the list element then such
element is deleted from the list:
> myList$second <-
2007 Oct 20
1
Getting at what a named object represents in a function...
Hi,
I'm pretty new to R.
I have an object (say a list) and I I have a function that I call on
various columns in that list (excuse terminology if it's wrong/ambiguous).
Imagine its like this (actual values are unimportant) and called mylist:
>mylist
A B
1 5
2 5
3 6 4 8
5 0
I have a function:
foo = function(param){
#modify list A or B values depending on
2004 May 10
2
Lists and outer() like functionality?
Hi,
I'm have a list of integer vectors and I want to perform an outer()
like operation on the list. As an example, take the following list:
mylist <- list(1:5,3:9,8:12)
A simple example of the kind of thing I want to do is to find the sum
of the shared numbers between each vector to give a result like:
result <- array(c(15,12,0,12,42,17,0,17,50), dim=c(3,3))
Two for() loops is the
2017 Jun 15
4
is.null(mylist[1]) and is.null(mylist$a) returns different values
Hi
I have a list :
mylist <- list( a = NULL, b = 1, c = 2 )
> mylist[1]
$a
NULL
> is.null(mylist[1])
[1] FALSE
> is.null(mylist$a)
[1] TRUE
why? I need to use mylist[1]
2005 Jan 30
3
trellis graphics in loops
I have this awkward problem with trellis (lattice). I am trying to
generate some plots through loops but the .eps file is empty. When I
generate them in a list and print them outside the loop all is fine. this
is an example below:( nothing shows up in foo.eps, but all show up in
foo1.eps)
R vesion 2.0.1, lattice version 0.10-16, on a debian 2.6.8-1 kernel.
X <- data.frame(x=rnorm(10000),
2001 Oct 18
2
Parsing for list components
How do I parse an identifier of a list component, e.g.
mylist$mycomponent
or
mylist[[1]] ?
Parse does not do the job, e.g.
parse(text="mylist$mycomponent")
returns an expression with just one term, instead of "mylist", "$",
"mycomponent".
What I need is a way to extract the list name (e.g. "mylist"), given
an identifier of a component.
2010 Sep 04
4
Please explain "do.call" in this context, or critique to "stack this list faster"
I've been doing some consulting with students who seem to come to R
from SAS. They are usually pre-occupied with do loops and it is tough
to persuade them to trust R lists rather than keeping 100s of named
matrices floating around.
Often it happens that there is a list with lots of matrices or data
frames in it and we need to "stack those together". I thought it
would be a simple
1999 May 09
1
subscripting in list() (PR#187)
Sorry My previous report is not detailed.
In R, you will get this:
> mylist <- list()
> mylist[[1]]
Error in mylist[[1]] : subscript out of bounds
> mylist[[1]] <- c(1)
Error: (list) object cannot be coerced to vector type 14
> mylist[[1]] <- c(1,2)
> mylist[[1]] <- c(1)
> mylist
[[1]]
[1] 1
I was trying to assigning c(1) to (mylist[[1]] <- c(1)) -- it seems
2010 Mar 18
1
Substitute NAs in a data frame
Excuse me for what I'm sure is a stupid beginner's question, but I've
given up trying to find the answer to this question from the help,
RSiteSearch, or any of the usual places.
I have a list that looks like this:
>myList
$first
[1] "--" "18" "8" "32"
$second
[1] "--" "--" "40" "54"
I want a
2017 Jun 15
0
is.null(mylist[1]) and is.null(mylist$a) returns different values
Hi,
Try
> is.null(mylist[[1]])
[1] TRUE
Notice the double square brackets.
From: ?`[`
"The most important distinction between [, [[ and $ is that the [ can
select more than one element whereas the other two select a single
element."
On Thu, Jun 15, 2017 at 11:33 AM, ce <zadig_1 at excite.com> wrote:
> Hi
>
> I have a list :
>
> mylist <- list( a = NULL, b
2012 Aug 28
3
Get variable data Reading from the list
Here i have a variable
MyVar <- data.frame(read.csv("D:\\Doc.csv"))
And now i am storing this variable name into a list.
MyList <- list()
MyList [length(MyList )+1]<- "MyVar"
Now what is the requirement is,
i need to call the variable name "MyVar" from the list "MyList " and get
the data.