Displaying 20 results from an estimated 40000 matches similar to: "Incrementing a counter in lapply"
2006 Mar 15
2
lapply vs. for (was: Incrementing a counter in lapply)
> From: Thomas Lumley
>>
>> On Tue, 14 Mar 2006, John McHenry wrote:
>>
>> > Thanks, Gabor & Thomas.
>> >
>> > Apologies, but I used an example that obfuscated the question that I
>> > wanted to ask.
>> >
>> > I really wanted to know how to have extra arguments in
>> functions that
>> > would allow,
2013 Mar 10
2
list + lapply insead of matrix + apply
I need to develop a simple list manipulation. Although it seems easier to
do it in matrix form, but I need it in list form.
I have a matrix
x <- matrix(c(12.1, 3.44, 0.1, 3, 12, 33.1, 1.1, 23), nrow=2)
for list form example, the conversion is
x.list <- lapply(seq_len(nrow(x)), function(i) x[i,])
### list version
calcnorm=function(a, b){
diff <- mapply("-", a, b)
2006 Jun 28
2
hopefully my last question on lapply
Marc and many other people ( whose names escape me ) have been
very helpful in explaining the use of lapply to me.
In his last response, Marc explained that if tradevectors is a list
of vectors of different lengths ( excuse my terminology ) then
lapply(tradevectors,function(x) G[x]*B[x] )
will go through each component of the list as if it was a vector
and apply the element by element
2005 Mar 18
4
passing arguments to FUN in lapply
Suppose I have a nx2 matrix of data, X, the following code generate
density estimation for each column and plot them
denlist <- apply(X, 2, density)
par(mfrow=c(1,2))
lapply(denlist, plot)
Does anyone know how to change the main title of each density plot
to "var 1", "var 2" by passing optional argument "main"? I've tried
lapply(denlist, plot,
2013 Apr 17
2
use of names() within lapply()
Dear all,
List g has 2 elements
> names(g)
[1] "2009-10-07" "2012-02-29"
and the list plot
lapply(g, plot, main=names(g))
results in equal plot titles with both list names, whereas distinct titles names(g[1]) and names(g[2]) are sought. Clearly, lapply is passing 'g' in stead of consecutively passing g[1] and then g[2] to process the additional 'main'
2010 Feb 17
1
lapply to apply a function using a vector
Hi,
First, thank you all for your help.
Here is my problem (simplified):
Say I have a list:
a=list(matrix(50,nrow=5,ncol=5),matrix(25,nrow=5,ncol=5),matrix(10,nrow=5,ncol=5))
I'd like to use rbinom with a different probability for each matrix. I
tried:
b=c(.8,.1,.9)
brep=rep(b,each=25)
lapply(a,function(a) rbinom(25,a,brep))
but that doesn't work-- it just uses the first value of b
2010 Mar 26
3
Using lapply with two lists
Hello guys,
I have a list L1 of matrix. I have another list L2 with the same number of
elements representing the row of the L matrix that I want to delete
(L1[[i]][-L2[[i]],]) but I can't do this with lapply as it iterates through
L1 (first argument) and not L2. Any idea?
-----
Anna Lippel
--
View this message in context:
2013 Jan 23
3
Pasting a list of parameters into a function
I need to repeat a function many times, with differing parameters held
constant across iterations. To accomplish this, I would like to create a
list (or vector) of parameters, and then insert that list into the function.
For example:
q<-("l,a,b,s")
genericfunction<-function(q){
}
######
The equivalent code would of course be
genericfunction<-function(l,a,b,s){
}
Any help
2009 Jun 23
2
an idiom to handle i'th element of a set of lists simultaneously
Hi, I have 3 lists, x, y, z and I'd like to perform a calculation over all
the lists simultaneously. If it were a single list I could use lapply, but
for more than one list I'm using a for loop. Is there an idiom that would
let me use something like lapply, but the function specified to lappy would
have access to an element from each list? (In Python, I would have used for
a,b,c in
2010 Sep 21
2
lapply version with [ subseting - a suggestion
Dear R developers,
Reviewing my code, I have realized that about 80% of the time in the lapply I
need to access the names of the objects inside the loop.
In such cases I iterate over indexes or names:
lapply(names(x), ... [i]),
lapply(seq_along(x), ... x[[i]] ... names(x)[i] ), or
for(i in seq_along(x)) ...
which is rather inconvenient.
How about an argument to lapply which would specify the
2009 Nov 19
5
Accessing list names in lapply
Hi,
When using lapply (or sapply) to loop over a list, can I somehow access the
index of the list from inside the function?
A trivial example:
df1 <- split(
x=rnorm(n=100, sd=seq(from=1, to=10, each=10)),
f=letters[seq(from=1, to=10, each=10)]
)
str(df1)
#List of 10
# $ a: num [1:10] -0.801 0.418 1.451 -0.554 -0.578 ...
# $ b: num [1:10] -2.464 0.279 4.099 -2.483 1.921 ...
# $ c: num
2006 Mar 10
2
lapply and list attributes
Hi
I have a list that has attributes:
attributes(lis[2])
$names
[1] "150096_at"
I want to use those attributes in a function and then use lapply to
apply that function to every element of the list, eg for simplicity's
sake:
my.fun <- function(x) {
attributes(x)
}
Then
l2 <- lapply(lis, my.fun)
It seems that "attributes(x)" within the function is not the
2006 Mar 30
3
access list component names with lapply
I have a question regarding accessing the names of list
components when applying a function with lapply.
Here is an example that demonstrates what I'd like to do.
I have a list like this one:
mylist <- list(a=letters[1:10], b=letters[10:1], c=letters[1:3])
Now I would like to append the names of the list components to their
corresponding vectors with the c() function. I thought this
2008 Jan 08
1
using lapply()
useR's,
I am trying to find a quick way to change some values in a list that are
subject to a condition to be NA. Consider the 3x1 matrix:
delta <- matrix(c(2.5,2.5,1), nrow = 1)
And consider the list named v that has 3 elements
> v
v[[1]]
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
[,13] [,14]
[1,] 4.25 3.25 2.25 1.25 0.25 0.75 1.75 2.75 3.75 4.25
2015 Mar 01
1
iterated lapply
> There are other instances, such as Reduce where there is a bug
> report pending that amounts to the same issue. Performing surgery on
> expressions and calling eval is not good practice at the R level and
> probably not a good idea at the C level either. It is worth thinking
> this through carefully before a adopting a solution, which is what we
> will be doing.
Surgery on
2005 Dec 06
3
reading in data with variable length
I have very large csv files (up to 1GB each of ASCII text). I'd like to be able to read them directly in to R. The problem I am having is with the variable length of the data in each record.
Here's a (simplified) example:
$ cat foo.csv
Name,Start Month,Data
Foo,10,-0.5615,2.3065,0.1589,-0.3649,1.5955
2006 Sep 03
3
Merge list to list - as list
Dear all,
#Last week, I asked about merge x and y as list.
#Now I have a dataset with list of list like:
x <- list(list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)),
list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)))
y <- list(list(c(1, -1, -1, 1, 1),c(1, 1, -1, -1, -1)),
list(c(1, 1, 1, 1, 1),c(1, 1, -1, 1, -1)))
x
y
#I need merge x and y, I have tried with
list.uni <-
2009 Dec 14
1
lapply , mapply questions
Dear all,
i have a programming problem that should be simple, though i am stuck with it. Please note that this is not a specific geonames problem, though i use it as an example - it´s just a basic problem with lapply.
I use the geonames webservices with the R geonames packages which works almost smoothly.
I have a vector of Zipcodes and i want to do a geonames lookup for all of them, which
2006 Aug 31
2
Wish: keep names in mapply() result
Hello!
I have noticed that mapply() drops names in R 2.3.1 as well as in
r-devel. Here is a simple example:
l <- list(a=1, b=2)
k <- list(1)
mapply(FUN="+", l, k)
[1] 2 3
mapply(FUN="+", l, k, SIMPLIFY=FALSE)
[[1]]
[1] 2
[[2]]
[1] 3
Help page does not indicate that this should happen. Argument USE.NAMES
does not have any effect here as it used only in a bit special
2012 Mar 12
2
mapply & assign to generate functions
Hi,
I have a problem that I'm finding a bit tricky. I'm trying to use
mapply and assign to generate curried functions. For example, if I
have the function divide
divide <- function(x, y) {
x / y
}
And I want the end result to be functionally equivalent to:
half <- function(x) divide(x, 2)
third <- function(x) divide(x, 3)
quarter <- function(x) divide(x, 4)
But I want