search for: prey

Hi, I have data on stomach contents. Possible prey species are in the hundreds, so a list of prey codes has been in used in many labs doing this kind of work. When comes time to do analyses on these data one often wants to regroup prey in broader categories, especially for rare prey. In SAS you can nest a large number of "if-else", o...

Hi, I'm trying to move to R the last few data handling routines I was performing in SAS. I'm working on stomach content data. In the simplified example I provide below, there are variables describing the origin of each prey item (nbpc is a ship number, each ship may have been used on different trips, each trip has stations, and individual fish (tagno) can be caught at each station. For each stomach the number of lines corresponds to the number of prey items. Thus a variable identifies prey type, and others (h...

Hi R experts :) I'm trying to carry out a survival model on my data, but I am unsure of whether it's appropriate or if I should do something specific in regards to hazard. My data is time to death by predator where I have 8 prey and one predator in the setting. This means that two prey can't possibly die at the same time and I can't quite get my head around how to include this in the model. I have repeats, so I have 15 replicates of the 8 prey one predator setting. What I have done so far is include replicate as a...

I have installed Prey onto my pc running PCLinuxOS following the instructions in http://frankscorner.org/index.php?p=prey or http://appdb.winehq.org/objectManager.php?sClass=application&iId=3465 and tried running it. I then found I needed the nocd patch, which I downloaded and applied. I then tried cd to the app fo...

...specifying a right model for my analysis. I am a beginner to lme methods and though have spent already many hours studying from various books an on-line helps, I was unfortunately not able to find a solution to my problem on my own. Data structure: I studied escape behavior of three species of a prey to a predator. The prey specimens (many) were in a vessel, together with one predator. Escape responses were video-recorded when a prey approached the predator close enough and jumped consequently away. Each set was run twice with a fresh predator and a fresh set of the prey specimens, leading to t...

Dear R-users, I am currently modifying a previously developed predator prey model and was curious if there was a way to add in a disturbance to the model (let's say at time t=100). The disturbance can be the introduction of 40 prey (N=40) and 10 predators (Pred = 10). I would like to see my model go from a state of equilibrium (up to t = 99), show this disturbance (a...

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...pecies that have different parameters but the same behaviour) I demonstrate this using the Lotka Volterra example. The code below does not work and I have not a good idea how to specify this right. ## ======================================================================= ## Example1: Predator-Prey Lotka-Volterra model (with logistic prey) ## ======================================================================= LVmod <- function(Time, State, Pars) { with(as.list(c(State, Pars)), { # Now there are different species of Prey so Prey is a one dimensional vector, #Ingestion is also a one-d...

Dear R friends- I'm attempting to generate a regression tree with one gradient predictor and multiple responses, trying to test if change in size (turtle.data$Clength) acts as a single predictor of ten multiple diet taxa abundances (prey.data) Neither rpart or mvpart seem to allow me to do multiple responses. (Or if they can, I'm not using the functions properly.) > library(rpart) > turtle.rtree<-rpart(prey.data~., data=turtle.data$Clength, method="anova", maxsurrogate=0, minsplit=8, minbucket=4, xval=10);...

Hello again. Since my last post about giving up on Prey I have had to change my graphics card. The cooling fan on my ATI packed up and it was a choice of a new fan/heatsink combination and having to nearly rebuild my pc to allow room for it (nearly the size of my card and over 1 inch thick !) or replacing the card. Since I thought that the fan problem m...

I'm fairly new to R, and I'm trying to write out a population model that satisfies the following; the system consists of s species, i= 1, 2,...,s network of interactions between species is specified by a (s x s) real matrix, C[i,j] x[i] being the relative population of the "ith" species (0 =< x[i] =< 1, sum(x[i]=1) the evolution rule being considered is as follows;

Hi I am struggling with the correct code syntax to generate xyplots that are different from the default graphics option. This is simplified version of my data: site size dnaconc prey A 44 22.6 1 A 47 18.2 1 B 38 25.6 0 B 47 20.5 1 C 45 30.5 0 C 32 18.5 0 D 45 15.0 1 D 22 20.1 0 So I am using xyplot(dnaconc~size|site,data=bug,groups=prey) to generate 4 panels (one for each site). My questions are: (1) How do I display different groups(ie prey) within each panel with...

Dear list, I´m using the mgcv package to model the proportion by weight of certain prey on the stomach content of a predator. This proportion is the ratio of two weights (prey weight over stomach weight), and ranges between 0 and 1. The variance is low when proportion is close to 0 and 1, and higher at intermediate values. It seems that the best way to go is to model this using the...

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Hello, I am trying to model a type II functional response of number of prey eaten (Ne) against number supplied (No) with a non-linear least squares regression (nls). I am using a modification of Holling's (1959) disc equation to account for non-replacement of prey; Ne=No{1-exp[a(bNe-T)]} where a is the attack rate, b is the handling time, and T is the experimental pe...

...replies? If so I intend to properly cite its use?!?). Regards, Eduardo Esteves ps - Sorry for not explaining the "biological details" of my posting: RNA/DNA is the ratio of RNA content to DNA content obtained for individual fish larvae (plus for each one I noted if it had visible prey items in the gut or not, thus the levels Prey and Empty of factor Gut); and sl is the standard length (distance from the tip of snout to the posterior extremity of the hypurals, the expanded bones at the end of the backbone that support the caudal fin, in mm) of the specimens. In the MS, I...

...t (last month) versions of the packages I need to use at present. I'm interested in examining hierarchical spatio-temporal patterns in a data set. The data consist of 94 points (X, Y, UTM coordinates) at which catch rates for a fish were recorded and there are also estimates of prey available for these fish at the same locations. I have reason to believe that the relationships between predators and prey varies with spatial scale (nested processes). To test this hypothesis, I'd like to generate subsets of the points that are separated by distance ranges (1-...

Hello there I have the following model based on the hollings disc equation for the type II functional response for 2 data sets: nls(eaten~(a*suppl)/(1+a*h*suppl) where eaten is the number of prey eaten by a predator and suppl is the number of prey initially supplied to the same predator. I have parameter estimates of 'a' and 'h' for the two populations studied and would like to know if there is a significant different in the estimates between the two i.e. a1 vs a2, h1 vs h2...

...on that passing in CC and CXX via env variables wouldn't work. Things work now, so that assumption is obviously wrong. I still don't like environment variables. They tend to remain in effect long after I forgot that I set them, creating all sorts of hassle. In fact I suspect I already fell prey to this, getting llvm to compile and check one day and nearly despairing when trying to reproduce that success on the next day. But, well, you use what you need to use to get the job done, so there :-) Regards, Jo

Dear Team, I have installed and configured gluster in one server and client. one time it was worked fine, again later it is not working. my configuration files. server [root at rhel2 ~]# cat /etc/glusterfs/glusterfs-server.vol volume rhel2 type storage/posix # POSIX FS translator option directory /opt # Export this directory end-volume volume rhel2 type