search for: fish_ids

Hi, I'm new to R and new to this forum. I'm struggling with trying to extract certain rows of data from my data.frame. The data.frame has eleven columns. Among those columns are "FISH_ID" and "DATE_TIME". FISH_ID is a factor. For each of my 21 unique FISH_IDs (levels) I have a few to a few thousand rows, each row with a unique DATE_TIME value. I would like to obtain, for each FISH_ID, the entire record from the data.frame with the latest DATE_TIME value (i.e. max (DATE_TIME). Thus, the resulting subset would be the original eleven columns by 21 rows (on...

Dear list, I would like to create a time series plot in which the paths of several individuals are stacked above each other, with the x-axis being the total observation period of three years ( 1.1.2004 to 31.12.2007) and the y-axis being some defined range[min,max]. My data consist of Date/Time information and the paths of 45 individual as the distance from the location of release. An example

Dear list, ? I am intersted in estimating movement based kernel densities for fish that were relocated at fixed receivers positioned along the coast. These data tend to display both a drift movment between receivers and a random movement component that can be estimated from the mean and the variance of the transit time between receivers. ?If I obtain an estimate of the diffusion coefficient from