Folks, I have been encountering a problem when using the adehabitatLT package and specifically the function as.ltraj and I was hoping someone could give me a clue on how to solve the problem!
I am working with GPS data. I have got 20 different files with tracks that I have merged together; it looks like I have successfully created a POSIXct column that I added to the dataframe and I have one column with latitude and one with longitude, as well as an ID column that has the ID of my individual birds; however, when I use the as.ltraj function, I get the following error: "Error in as.ltraj(xy = data_used[, c("latitude", "longitude")], date = data_used$timestamp, : some id's are not present in the data" I tried different things (without naming the columns first and with column names, with or without "-" in the ID numbers, using just the relevant columns with no additional information.) and nothing is fixing the problem. I also do not understand the error message because when I check the length of the relevant columns, there are the same. Here is my code: setwd("C:/Users/Elodie/Documents/Deakin/Data analysis/GPS data analysis/Processed LB multiple tracks") file_list<-list.files(pattern="*.csv", full.names=TRUE) require(data.table) #merge all the files in the working directory in one dataframe dataset = rbindlist(lapply( file_list, fread )) write.csv(dataset, file = "dataset_multiple_trips_LB.csv", row.names = F) data<-read.csv("dataset_multiple_trips_LB.csv", header=F) data_used<-data[-1,] #V3 is the Date column, V4 is the Time column timestamp <- as.POSIXct(strptime(as.character(paste(data_used$V3, data_used$V4)),"%Y/%m/%d %H:%M:%S"), "GMT") data_used <- data.frame(data_used, V11 = timestamp) colnames(data_used)<-c("id", "index", "date", "time", "latitude", "longitude", "speed", "course", "distance", "EHPE", "timestamp") everybody<-as.ltraj(xy = data_used[,c("latitude","longitude")], date = data_used$timestamp, id = data_used$id) Error in as.ltraj(xy = data_used[, c("latitude", "longitude")], date = data_used$timestamp, : some id's are not present in the data If I do the following code, I get the following results > length(data_used$id) [1] 14444 > length(data_used$timestamp) [1] 14444 > length(data_used$longitude) [1] 14444 > length(data_used$latitude) [1] 14444. Thanks in advance for pointing me in the right direction! Elodie Elodie Camprasse 6/187 Auburn Road Hawthorn, VIC 3122 Australia Email: <mailto:elodie.campra...@gmail.com> elodie.campra...@gmail.com Website: <http://hors-des-sentiers-battus.e-monsite.com/> http://hors-des-sentiers-battus.e-monsite.com/ Mobile: <tel:%28%2B61%29%20049%20794%200793> (+61) 049 794 0793
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