[R] date and time functions
Dear R community I would like to perform some statistical analysis on a data set containing the following items: date, time, index of observation and various covariates. The date and time are originally extracted in the following format: dd.mm. and hh:mm:ss respectively. R and more precisely the function read.table() seems to read the data properly. In a second step, I would like to sort and subset the data according to daytime, day of the week, month, season but I get into trouble when trying to use the built-in functions with this format. Which is the most convenient date and time format in R to perform such kind of work? Is there any specific, powerful and well documented package containing various date and time functions? Many thanks in advance Best regards ___ Robert M. Kalicki, MD Postdoctoral Fellow Department of Nephrology and Hypertension Inselspital University of Bern Switzerland Address: Klinik und Poliklinik für Nephrologie und Hypertonie KiKl G6 Freiburgstrasse 15 CH-3010 Inselspital Bern Tel +41(0)31 632 96 63 Fax+41(0)31 632 14 58 [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] post-hoc test with kruskal.test()
Dear R users, I would like to know if there is a way in R to execute a post-hoc test (factor levels comparison, like Tukey for ANOVA) of a non-parametric analysis of variance with kruskal.test() function. I am comparing three different groups. The preliminary analysis using the kruskal-wallis-test show significance, but I still don't know the relationship and the significance level between each group? Do you have any suggestion? Many thanks in advance! Robert ___ Robert M. Kalicki, MD Postdoctoral Fellow Department of Nephrology and Hypertension Inselspital University of Bern Switzerland Address: Klinik und Poliklinik für Nephrologie und Hypertonie KiKl G6 Freiburgstrasse 15 CH-3010 Inselspital Bern Tel +41(0)31 632 96 63 Fax+41(0)31 632 14 58 [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] Integrating a function
Hello everybody!
I have problems with integrating my function.
My primary function is a survival function of the following type:
surviv - exp(-k*x)/(1+exp(alpha*(x-tau)))
I would like to integrate this function over a defined range and obtain a
vector with all the values from integrate(surviv, 0, x) for x - 1:N.
I unfortunately obtain just a scalar value corresponding to the last
integrated x.
How do I have to proceed if I want to obtain a vector with all the results?
I have tried to solve this problem by adding a while loop. It works but
the expression becomes to complex if I want to perform further optimization.
Have any one a solution for this problem?
Thanks a lot in advance.
Example
# General equation
beta1 - 0.001
beta2 - 0
Hct0 - 0.27
tau - 70
k - 0.001
alpha - 0.3
T2 -40
step - function(x){
if(x=0) step - 1
else step - 0
}
Nmax - 250
n - 1
while(nNmax){
surviv - function(n){
surviv - exp(-k*n)/(1+exp(alpha*(n-tau)))
}
geq - function(n){
geq -
Hct0+beta1*as.integer(integrate(surviv,0,n)[1])+step(n-T2)*(beta2-beta1)*as.
integer(integrate(surviv,0,n-T2)[1])
}
plot(n, geq(n), type=p, pch=19, xlim=c(0,250),
ylim=c(0.25,0.35), xlab=time in days, ylab=Hct)
par(new=T)
print(c(n, surviv(n), geq(n),
as.integer(integrate(surviv,0,n)[1]))
n - n + 1
}
Robert M. Kalicki, MD
Department of Nephrology and Hypertension
University of Bern
Abteilung für Nephrologie und Hypertonie (KiKl G5)
Freiburgstrasse 15
CH-3010 Inselspital
Tel: +41316329663
Fax:+41316329734
[[alternative HTML version deleted]]
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
