Displaying 20 results from an estimated 3000 matches similar to: "Canberra dist and double zeros"
2010 Feb 06
1
Canberra distance
Hi the list,
According to what I know, the Canberra distance between X et Y is : sum[
(|x_i - y_i|) / (|x_i|+|y_i|) ] (with | | denoting the function
'absolute value')
In the source code of the canberra distance in the file distance.c, we
find :
sum = fabs(x[i1] + x[i2]);
diff = fabs(x[i1] - x[i2]);
dev = diff/sum;
which correspond to the formula : sum[ (|x_i - y_i|) /
2018 Mar 15
0
stats 'dist' euclidean distance calculation
> 3x3 subset used
> Locus1 Locus2 Locus3
> Samp1 GG <NA> GG
> Samp2 AG CA GA
> Samp3 AG CA GG
>
> The euclidean distance function is defined as: sqrt(sum((x_i - y_i)^2)) My
> assumption was that the difference between
2018 Jan 17
1
mgcv::gam is it possible to have a 'simple' product of 1-d smooths?
I am trying to test out several mgcv::gam models in a scalar-on-function regression analysis.
The following is the 'hierarchy' of models I would like to test:
(1) Y_i = a + integral[ X_i(t)*Beta(t) dt ]
(2) Y_i = a + integral[ F{X_i(t)}*Beta(t) dt ]
(3) Y_i = a + integral[ F{X_i(t),t} dt ]
equivalents for discrete data might be:
1) Y_i = a + sum_t[ L_t * X_it * Beta_t ]
(2) Y_i
2018 Mar 15
3
stats 'dist' euclidean distance calculation
Hello,
I am working with a matrix of multilocus genotypes for ~180 individual snail samples, with substantial missing data. I am trying to calculate the pairwise genetic distance between individuals using the stats package 'dist' function, using euclidean distance. I took a subset of this dataset (3 samples x 3 loci) to test how euclidean distance is calculated:
3x3 subset used
2004 Apr 18
2
lm with data=(means,sds,ns)
Hi Folks,
I am dealing with data which have been presented as
at each x_i, mean m_i of the y-values at x_i,
sd s_i of the y-values at x_i
number n_i of the y-values at x_i
and I want to linearly regress y on x.
There does not seem to be an option to 'lm' which can
deal with such data directly, though the regression
problem could be algebraically
2010 Apr 25
1
function pointer question
Hello,
I have the following function that receives a "function pointer" formal parameter name "fnc":
loocv <- function(data, fnc) {
n <- length(data.x)
score <- 0
for (i in 1:n) {
x_i <- data.x[-i]
y_i <- data.y[-i]
yhat <- fnc(x=x_i,y=y_i)
score <- score + (y_i - yhat)^2
}
score <- score/n
2007 Feb 01
3
Help with efficient double sum of max (X_i, Y_i) (X & Y vectors)
Greetings.
For R gurus this may be a no brainer, but I could not find pointers to
efficient computation of this beast in past help files.
Background - I wish to implement a Cramer-von Mises type test statistic
which involves double sums of max(X_i,Y_j) where X and Y are vectors of
differing length.
I am currently using ifelse pointwise in a vector, but have a nagging
suspicion that there is a
2007 Mar 01
1
covariance question which has nothing to do with R
This is a covariance calculation question so nothing to do with R but
maybe someone could help me anyway.
Suppose, I have two random variables X and Y whose means are both known
to be zero and I want to get an estimate of their covariance.
I have n sample pairs
(X1,Y1)
(X2,Y2)
.
.
.
.
.
(Xn,Yn)
, so that the covariance estimate is clearly 1/n *(sum from i = 1 to n
of ( X_i*Y_i) )
But,
2008 Dec 01
1
linear functional relationships with heteroscedastic & non-Gaussian errors - any packages around?
Hi,
I have a situation where I have a set of pairs of X & Y variables for
each of which I have a (fairly) well-defined PDF. The PDF(x_i) 's and
PDF(y_i)'s are unfortunately often rather non-Gaussian although most
of the time not multi--modal.
For these data (estimates of gas content in galaxies), I need to
quantify a linear functional relationship and I am trying to do this
as
2010 Feb 05
3
metafor package: effect sizes are not fully independent
In a classical meta analysis model y_i = X_i * beta_i + e_i, data
{y_i} are assumed to be independent effect sizes. However, I'm
encountering the following two scenarios:
(1) Each source has multiple effect sizes, thus {y_i} are not fully
independent with each other.
(2) Each source has multiple effect sizes, each of the effect size
from a source can be categorized as one of a factor levels
2005 Jun 15
2
need help on computing double summation
Dear helpers in this forum,
This is a clarified version of my previous
questions in this forum. I really need your generous
help on this issue.
> Suppose I have the following data set:
>
> id x y
> 023 1 2
> 023 2 5
> 023 4 6
> 023 5 7
> 412 2 5
> 412 3 4
> 412 4 6
> 412 7 9
> 220 5 7
> 220 4 8
> 220 9 8
> ......
>
Now I want to compute the
2004 Dec 15
2
how to fit a weighted logistic regression?
I tried lrm in library(Design) but there is always
some error message. Is this function really doing the
weighted logistic regression as maximizing the
following likelihood:
\sum w_i*(y_i*\beta*x_i-log(1+exp(\beta*x_i)))
Does anybody know a better way to fit this kind of
model in R?
FYI: one example of getting error message is like:
> x=runif(10,0,3)
> y=c(rep(0,5),rep(1,5))
>
2003 Oct 23
1
Variance-covariance matrix for beta hat and b hat from lme
Dear all,
Given a LME model (following the notation of Pinheiro and Bates 2000) y_i
= X_i*beta + Z_i*b_i + e_i, is it possible to extract the
variance-covariance matrix for the estimated beta_i hat and b_i hat from the
lme fitted object?
The reason for needing this is because I want to have interval prediction on
the predicted values (at level = 0:1). The "predict.lme" seems to
2005 May 04
1
MacOS X: update.packages(type="mac.binary") fails (PR#7834)
Dear Mr Moderator, please let me through. I want to reply to my own
thread. I once subscribed to this list, but then my subscription was not
accepted.
Now to the business:
The final failure came from missing .install.macbinary() function. I
grepped R-patched sourcesand the only instance of .install.macbinary()
was the call to the function in R-
patched/src/library/utils/R/packages2.R (stupid
2011 Jul 19
1
notation question
Dear list, I am currently writing up some of my R models in a more
formal sense for a paper, and I am having trouble with the notation.
Although this isn't really an 'R' question, it should help me to
understand a bit better what I am actually doing when fitting my
models!
Using the analysis of co-variance example from MASS (fourth edition, p
142), what is the correct notation for the
2002 Oct 30
4
Sweave in packages
Dear R folks,
One of the fantastic new tools in R is `Sweave'. I have tested it so much that I
know it works and produces fine documentation, and with (GNU) Emacs/ESS it is
nice to work with, too. I started to have a look at including some Swoven (is
that a strong verb?) documentation with my R package, but it seems that there is
no model to copy among those packages that I have installed in
2009 Dec 01
0
Canberra distance
Hi,
I am using R 2.9.0. It seems the documentation for the calculation of
Canberra distance using stats::dist is ambiguous. Does anyone have the
original definition given in the Lance & Williams paper from Aust. Comput.
J. 1, 15-20, 1967?
When there are zeros at certain position in both vectors, they are not
omitted as documented in the function (see below). Instead, Canberra
distance is
2005 Aug 31
1
Why should package.skeleton() fail R CMD check?
I find it a bit peculiar that a package skeleton created with a utils
function package.skeleton() fails subsequent R CMD check. I do
understand that the function is intended to produce only a skeleton that
should be edited by the package author. I think that it would be
justified to say that the skeleton *should* fail the test. However, I
have two arguments against intentional failure:
* When you
2005 Jul 07
1
CDF plot
Dear all,
I have define a discrete distribution P(y_i=x_i)=p_i, which I want to
plot a CDF plot. However, I can not find a function in R to draw it
for me after searching R and R-archive. I only find the one for the
sample CDF instead my theoretical one.
I find stepfun can do it for me, however, I want to plot some
different CDF with same support x in one plot. I can not manage how to
do it with
2013 Mar 02
1
Errors-In-Variables in R
In reference to [1], how would you solve the following regression
problem:
Given observations (X_i,Y_i) with known respective error distributions
(e_X_i,e_Y_i) (say, 0-mean Gaussian with known STD), find the parameters
a and b which maximize the Likelihood of
Y = a*X + b
Taking the example further, how many of the very simplified assumptions
from the above example can be lifted or eased and R