Displaying 20 results from an estimated 8000 matches similar to: "Find the index for min of a matrix"
2008 Feb 13
2
apply on large arrays
I have a big contingency table, approximately of size 60*2*500*500,
and I need to count the number of cells containing a count of 1 for each
of the factors values defining the first dimension.
Here is my attempt:
tab1<-with(pisa1,table(CNT,GENDER,ISCOF,ISCOM))
tab2<-apply(tab1,1:4,function(x)ifelse(sum(x)==1,1,0))
tab3<-apply(tab2,1,sum)
Computing tab2 is very slow.
Is there a faster
2008 Feb 01
6
Accessing the elements of a list
Hi R,
I wanted to know how do we access the elements of a list. In particular,
v=list(c(1,2,3,4,5),c(1,2,33,4,5),c(1,2,333,4,5),c(1,2,3333,4,5))
I want to access all the thirds items of the elements of the list. i.e.,
I want to access the elements, 3,33,333,3333. This can be done through
sapply as:
sapply(v,function(x) x[3])
But I need to access this without using
2007 Jul 03
1
termplot - changes in defaults
While termplot is under discussion, here's another proposal. I'd like to
change the default for partial.resid to TRUE, and for smooth to
panel.smooth. I'd be surprised if those changes were to break existing
code.
John Maindonald email: john.maindonald at anu.edu.au
phone : +61 2 (6125)3473 fax : +61 2(6125)5549
Centre for Mathematics & Its Applications, Room
2008 Apr 13
4
R equivalent of erfcinv in matlab
I am converting some matlab code into R that use inverse of the
complementary error function, erfcinv and did not find an equivalent in
R, is there such a function in some contributed modules?
Thanks.
2007 Nov 15
3
generate combination set
I have a set data={A,B,C,D,E,F,G}
I want to choose 2 letter from 8 letters, i.e. generate the combination set
for choose 2 letters from 8 letters.
I want to get the liking:
combination set={AB,AC,AD,....}
Does anyone konw how to do in R.
thanks,
Aimin
2008 Mar 04
6
vector manipulations
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2007 Jul 02
2
termplot with uniform y-limits
Does anyone have, or has anyone ever considered making, a version of
'termplot' that allows the user to specify that all plots should have
the same y-limits?
This seems a natural thing to ask for, as the plots share a y-scale. If
you don't have the same y-axes you can easily misread the comparative
contributions of the different components.
Notes: the current version of termplot
2007 Jul 02
2
termplot with uniform y-limits
Does anyone have, or has anyone ever considered making, a version of
'termplot' that allows the user to specify that all plots should have
the same y-limits?
This seems a natural thing to ask for, as the plots share a y-scale. If
you don't have the same y-axes you can easily misread the comparative
contributions of the different components.
Notes: the current version of termplot
2008 Mar 07
5
Puzzling coefficients for linear fitting to polynom
Hi,
I can not comprehend the linear fitting results of polynoms. For
example, given the following data (representing y = x^2):
> x <- 1:3
> y <- c(1, 4, 9)
performing a linear fit
> f <- lm(y ~ poly(x, 2))
gives weird coefficients:
> coefficients(f)
(Intercept) poly(x, 2)1 poly(x, 2)2
4.6666667 5.6568542 0.8164966
However the fitted() result makes sense:
>
2008 Feb 26
1
The meaning of 'z value' and 'Pr(>|z|)' in the result of glm
Hi all,
I used the function 'glm' to perform logistic regression, and then use 'summary' to display the fitting result. There are 'z value' and 'Pr(>|z|)'
Do they simpily represent the result of 'z test' ? as I perform the 'z test' for a particular variable following the definition, it yields a different result.
Stephen Lau
2008 Mar 13
1
(no subject)
Hi there,
Am try to find tree diameter increment in a hierarchical data with tree
diameter measurements, date of measurements, in plots that are located in
different region. How do I do it? am very new to R.
Thanks for you help.
Maina Kariuki
Level 3, 8 Nicholson Street
East Melbourne VIC 3002
Ph: (03) 9637 9809
Email: maina.kariuki@dse.vic.gov.au
Notice:
This email and any
2008 Mar 14
2
How to turn a string into a variable name ?
Hi,
For example,
natural_nums <- 1:10
even_nums <- seq(2,10, by = 2)
types <- c("natural_nums", "even_nums")
What functions can be performed on types[1] to turn it into a variable name
and not a string ?
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2008 Mar 19
1
Anova of a nls object
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2008 Mar 25
1
peak finding
Hi all
Is there a function that can find the start and end position of peaks in a
set of numbers.
eg.
x=c(14,15,12,11,12,13,14,15,16,15,14,13,12,11,14,12)
y=somefunction(x)
y
4 14
Thanks
John
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2008 Mar 26
1
avoiding loops
Hi,
I need to compute an array from a matrix and an array:
A <- array(1:20,c(2,2,5))
B <- matrix(1:10,5)
And I would like the result to be an array consisting of the following:
rbind(A[1,,1]*B[1,],
A[2,,1]*B[1,])
rbind(A[1,,2]*B[2,],
A[2,,2]*B[2,])
rbind(A[1,,3]*B[2,],
A[2,,3]*B[2,])
etc.
Hence the result should have the same dimension as A, ie a series of
2 by 2 matrices.
Short of
2008 Apr 11
1
for loop help
Hi,
I am trying to find a solution in R for the following C++ code that allows
one to skip ahead in the loop:
for (x = 0; x <= 13; x++){
x=12;
cout << "Hello World";
}
Note that "Hello World" was printed only twice using this C++ loop. I
tried to do the same in R:
for(i in 1:13){
i=12
print("Hello World")
}
It doesn't work as I expected, i.e.,
2008 Apr 30
2
boxplots
Dear R user group,
I am working with boxplots and cannot solve the following problem:
> data<-c(0,15,0,60,0,0,0,0,0,60,60,0,60,0,30,0)
> data
[1] 0 15 0 60 0 0 0 0 0 60 60 0 60 0 30 0
> boxplot(data)
The boxplot has the first hinge and the mean-bar both at 0... Why is this
the mean is clearly >0!
Thanking you and wishing you an excellent day,
Georg.
2008 May 17
1
R to exe
hi, is there a way to compile r script , so that it can be run without the R
platform, both on unix and windows
something to create exe file.
thnx
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2008 Mar 09
2
question about matrix one column values matching a vector of values
Hi,
I have a matrix
a = matrix (1:16, 4, 4)
b = c (2,3)
I want to find out which rows of a, where a[,1] equals any values of b?
I know that if b is only one value, e.g, b=2, then what I want is a[a[,1] == 2,]
But what about if it is not one value but a vector of values?
Thanks much in advance.
--
Waverley @ Palo Alto
2008 May 20
2
Nonlinear regression
Could someone help me on the following:
SAS has DUD (Does not Use Derivatives) for nonlinear regression.
Does "R" has a similar capability?
I am not good at derivatives and may get my derivative wrong before
feeding it to a nonlinear regression procedure.
Any help would be much appreciated.
Liu
Hancock Forest Management NZ
Tokoroa, New Zealand
DDI: 07-8850387
Mobile: 021-1576178