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I know it is pretty old but it seems that nobody answer this question. I ran into similar problem and the work around I found use the assign function. Indeed it seems than stepAIC look for the element it needs...

Hi all, I am trying to merge ICES divisions polygons by subareas i.e. division IVa, IVb and IVc in the shapefile and I want to obtain IV (IVa+IVb+IVc). To realize that I thought to use the function...

Hi all, I'm trying to randomly select sample numbers for length class groups (5 per length class). For this I'm using a loop FOR and the function sample () and specified a size for the sampling of 5. Unfortunately...

Hi all, I'm encountering a problem I do not understand on my data: library (lattice) Mpool1 <- Table[Table$Subarea %in% c("52E9", "51E9"),] Mpool2 <- Table[Table$Subarea %in% c("53F0", "52F0"),] Mpool3 <- Table[Table$Subarea %in% c("51F0", "50F0...

Thank you Sarah for this code, it's exactly what I wanted to reach. Le 05/06/2013 16:49, Sarah Goslee a ?crit : > What about using instead > size = min(5, length(Gpool$SampleNb[Gpool$LngtClas == LngtClas[[4]]& > Gpool$SpCode...

Assuming you attribute the name "dataset" to your data. A way to name a column using colnames and which. Code to change V1 column name: colnames(dataset)[which(colnames(dataset) == "V1")] <- "Toto" You are asking to R in the column...

Here is a solution I applied using qAIC and package bbmle so I share it for next ones. It is not really automatized as I need to read every results of the drop() test an enter manually the less significant...

<>< <>< <>< <>< Xochitl CORMON Le 01/10/2013 17:29, Dimitri Liakhovitski a ?crit : > Thank you very much, Bert - it's very helpful. > This post says that R issues a warning: > > Warning message: > *glm.fit: fitted probabilities numerically 0 or 1 occurred...

You have what is called a "wide" table and you want a "tall" table. In this case the function melt from reshape2 package is suitable. Be careful specifying properly the variables (columns) you want to use for the reshape using...

Dear list, I am currently working with presence/absence GLM. Therefore I am using binomial family and selection my models this way : null <- glm(respvarPAT ~ 1 , family = binomial, data = datafit) full <- glm(respvarPAT ~ CSpp + FSpp + Gpp + Mpp + Ppp + Lpp + TempPoly2...

Dear all, I am trying to estimate VBGF parameters K and Linf using non linear regression and nls(). First I used a classic approach where I estimate both parameters together as below with "alkdyr" being a subset per year of...

Hi Jim, Thank you a lot. Is it a FAQ concerning lattice or FOR loop in general? Regards, Xochitl C. Le 05/06/2013 10:55, Jim Holtman a ?crit : > This is an FAQ. you have to explicitly 'print' the...

Le 01/10/2013 17:41, Dimitri Liakhovitski a ?crit : > Ah, thank you very much - I did not understand first brglm was the name > of a package! > Dimitri My bad! If there is separation you should see it in the...

Hi, I did have warning messages about convergence issues using binomial GLM with logit link with my data in the past.... Do you detect separation using the function separation.detection{brglm}? Regards, Xochitl C. <>< <>< <>< <>< Xochitl CORMON +33 (0)3 21...

Le 28/02/2013 17:22, Ben Bolker a ?crit : Thank you for your help ! > Xochitl CORMON<Xochitl.Cormon<at> ifremer.fr> writes: > >> Dear all, >> >> I am encountering some issues with my data and need some help. I am >> trying...

Thanks Thierry for your quick answer. Indeed this simplifies a lot my method so I decided to apply it. However I will be curious to check in which extend the coefficients obtained with the gls function are similar to the...

Hi all, Here is a description of my case. I am sorry if my question is also statistic related but it is difficult to disentangle. I will however try to make it only R applied. My response is a growth...

Dear all, I am encountering some issues with my data and need some help. I am trying to run glm analysis with a presence/absence variable as response variable and several explanatory variable (time, location, presence/absence data, abundance data...

Thank you for the tip. Indeed, nlxb in nlmrt works and results are not crazy. I would like however to assess goodness-of-fit (gof) and ultimately to compare it with gof from linear regression (fitted with same variables). Before...

Dear list, I found a message asking same kind of things I am wondering. Unfortunately I dont find proper answers and thus would like to update the topic. Maybe Xingli could you share what your learn from the authors with...