Displaying 20 results from an estimated 5000 matches similar to: "Selecting vector elements using other vectors"
2010 Nov 17
1
efficient conversion of matrix column rows to list elements
Hi List,
I'm hoping to get opinions for enhancing the efficiency of the following
code designed to take a vector of probabilities (outcomes) and calculate a
union of the probability space. As part of the union calculation, combn()
must be used, which returns a matrix, and the parallelized version of
lapply() provided in the multicore package requires a list. I've found that
2012 Nov 26
3
Passing lists between functions
I'd like to pass a list object created by one function as an argument of
another function. once inside the second function, I'd like to break the
list up to it's individual elements, each then identifiable by the 'names'
of the list.
The list looks something like
lst<-list(a=1, b=2, df=5, g=7)
then inside the function I've been writing a sequence of statements that
2008 Jan 18
1
Selecting rows conditionally between 2 data.frames
Hello everyone,
I have two data.frames that look like
calib:
place zoom scale
left 0.65 8
left 0.80 5.6
left 1.20 3
right 0.65 8.4
right 0.80 6
right 1.20 2.9
X:
... place zoom ....
... left 0.80 ....
... left 1.20 ....
... right 0.65 ....
... NA NA ....
... right 0.8 ....
... left 1.20 ....
and I want to get the corresponding values of 'scale' in a new column
2007 Aug 23
1
Expedite scalar f(x) evaluation over vectors
Dear R community,
I am trying to code a fairly complex equation for optim(). My current
approach is too slow for optim().
I have a function that takes a double integral (hopefully correctly) across
two terms, e.g.,
doubleint <- function(c1,c2) {integrate(function(y) {
sapply(y, function(y) {
integrate(function(x) {a*(c1+x)+b*(c2+x)}, boundsx[1], boundsx[2])$value
})
},
2009 Nov 09
1
multiple tests: t-statistic for vectors in 4-dimensional array
Hi everyone,
I created a four dimensional vector (dim (128,128,1,8)). This third
dimension is necessary for another function somewhere. Now I'd like to
perform a t-test on every vector of length 8 in my array on the fourth
dimension.
I'd like to obtain a new array of three dimensions with dimensions
128x128x1 with all these test statistics.
I tried this with a double loop:
A <-
2007 Apr 04
2
Finding a single unique item in duplicated vectors
I have a very simple problem and am completely missing
the solution.
I have two character variables (character ID's from
two datasets) Data set 'b'
is data set 'a' with one more subject added.
How do I find out which is the added subject?
I have tried duplicated and unique without much
success. I can find all the
duplicated ID's but how do I extract the new
2006 Oct 06
2
Extreme slowdown with named vectors. A bug?
Tried the following with R --vanilla on the Rv2.4.0 release (see
details at the end). I think the script and its comments speaks for
itself, but the outcome is certainly not wanted.
for (n in 58950:58970) {
cat("n=", n, "\n", sep="");
# Clean up first
rm(names, x, y); gc();
# Create a named vector of length n
# Try with format "%5d" and it
2012 Aug 06
2
Identify points that lie within polygon
I have a complex 2D polygon with thousands of vertices, and I'd like to be
able to identify points from a large set contained within the polygon, and
was wondering if there might be an efficient way of doing this? Any advice
would be useful! Here is a small example of what I mean:
# make polygon
v1<-c(0,1,1,2,1,3,6,7)
v2<-c(1,3,3,5,6,7,8,9)
plot(v1, v2, type = "n" )
2009 Oct 13
7
lapply() reccursively
Hi all,
I was wondering whether it is possible to use the lapply() function
to alter the value of the input, something in the spirit of :
a1<-runif(100)
a2<-function(i){
a1[i]<-a1[i-1]*a1[i];a1[i]
}
a3<-lapply(2:100,a2)
Something akin to a for() loop, but using the lapply() infrastructure.
I haven't been able to get rapply() to do this.
The reason is that the "real"
2006 Dec 10
4
sample "n" random positions from a matrix
Hi there,
I have a binary matrix (dim 100x100) filled with values 0 and 1. I need select a record "n" positions of that matrix when values are 1. How can I do that?
Thanks for all,
Miltinho
Brazil
---------------------------------
[[alternative HTML version deleted]]
2012 Feb 09
1
Row-wise kronecker product with Matrix package
I'm trying to calculate the row-wise kronecker product A \Box B of two
sparse matrices A and B, and am struggling to find a quick way to do this
that takes advantage of sparseness. I thought a good idea would be to use
"rep" to construct 2 matrices of the same dimension of the end product, and
multiply these two together:
library(Matrix)
A<-Matrix(c(1,0,0,0,0,1,2,0), 2, 4)
2010 Jul 07
3
How do I test against a simple null that two regressions coefficients are equal?
Hi there,
I run two regressions:
y = a1 + b1 * x + e1
y = a2 + b2 * z + e2
I want to test against the null hypothesis: b1 = b2. How do I design the test?
I think I can add two equations together and divide both sides by 2:
y = 0.5*(a1+a2) + 0.5*b1 * x + 0.5*b2 * z + e3, where e3 = 0.5*(e1 + e2).
or just y = a3 + 0.5*b1 * x + 0.5*b2 * z + e3
If I run this new regression, I can test against
2011 Dec 21
4
qqnorm & huge datasets
Hi,
When qqnorm on a vector of length 10M+ I get a huge pdf file which
cannot be loaded by acroread or evince.
Any suggestions? (apart from sampling the data).
Thanks.
--
Sam Steingold (http://sds.podval.org/) on Ubuntu 11.10 (oneiric) X 11.0.11004000
http://mideasttruth.com http://honestreporting.com http://camera.org
http://openvotingconsortium.org http://pmw.org.il
2019 Jun 07
2
[R] Open a file which name contains a tilde
> On Jun 6, 2019, at 2:04 PM, Richard O'Keefe <raoknz at gmail.com> wrote:
>
> How can expanding tildes anywhere but the beginning of a file name NOT be
> considered a bug?
>
>
I think that that IS what libreadline is doing if one allows a whitespace separated list of file names.
As reported in R-help,
https://www.mail-archive.com/r-help at
2011 Jan 24
2
Help with expression
I have a problem with expressions. I am trying to create a title where
the parameter of interest is displayed as a Greek character. Which
parameter is being considered is stored in a character variable.
As an example, if I have
param <- "alpha"
and then do
plot(0, 0, main = bquote(Parameter==.(param)))
then in the title I get "Parameter = alpha",
whereas I want the
2019 Jun 05
6
Open a file which name contains a tilde
Hi,
As I can see via path.expand a filename which contains a tilde anywhere gets automatically crippled.
+> path.expand("a ~ b")
[1] "a /home/user b"
+> path.expand("a ~ b ~")
[1] "a /home/user b /home/user"
I want to open a file regardless whether its name contains any character unless 0.
The unix filesystem allow the creation of such files, it
2019 Jun 05
6
Open a file which name contains a tilde
Hi,
As I can see via path.expand a filename which contains a tilde anywhere gets automatically crippled.
+> path.expand("a ~ b")
[1] "a /home/user b"
+> path.expand("a ~ b ~")
[1] "a /home/user b /home/user"
I want to open a file regardless whether its name contains any character unless 0.
The unix filesystem allow the creation of such files, it
2019 Mar 03
2
bug: sample( x, size, replace = TRUE, prob= skewed.probs) produces uniform sample
When `length( skewed.probs ) > 200' uniform samples are generated in R-devel.
R-3.5.1 behaves as expected.
`epsilon` can be a lot bigger than illustrated and still the uniform distribution is produced.
Chuck
> set.seed(123)
>
> epsilon <- 1e-10
>
> ## uniform to 200 then small
> p200 <- prop.table( rep( c(1, epsilon), c(200, 999-200)))
> ## uniform to 201
2008 May 27
4
help with simple function
I have a matrix of frequency counts from 0-160.
x<-as.matrix(c(0,1,0,0,1,0,0,0,1,0,0,0,0,1))
I would like to apply a function creating a new column (x[,2])containing
values equal to:
a) log(x[m,1]) if x[m,1] > 0; and
b) for all x[m,1]= 0, log(next x[m,1] > 0 / count of preceding zero values
+1)
for example, x[1,2] should equal log(x[2,1]/2) = log(1/2) = -0.6931472
whereas x[3,2] should
2008 Dec 11
3
check if a certain ... argument has been passed on to my user-defined function
Hi,
How can I check if a certain ... argument has been passed on to my
user-defined function or not?
foo <- function(data, ...)
{
### here I want to check whether xlab was passed with the ... arguments
### or if the ... arguments did not contain an xlab argument
}
I tried missing(xlab) , exists(xlab) and several other things but did not
find a solution.
TIA,
Mark