Extracting the first element of a list
Ko-Kang Kevin Wang wrote:
Hi, ----- Original Message ----- From: "Uwe Ligges" <ligges at amadeus.statistik.uni-dortmund.de> To: "Ross Darnell" <r.darnell at shrs.uq.edu.au> Cc: <r-help at stat.math.ethz.ch> Sent: Wednesday, March 27, 2002 8:03 PM Subject: Re: [R] Extracting the first element of a list
For the first element of a list L: L[[1]] For the first elements of all elements (vector) of the list: lapply(L, function(x) x[1])
So, suppose I've got a vector called foo, which has elements as follows: 305 159 251 215 101 224 306 199 194 325 329 221 318 238 17 .... (the rest omittied) And suppose I want to extract out the first digit of each number, so like: 3 1 2 2 1 2 3 1 1 3 3 2 3 2 1... Do I still use lapply(foo, function(x) x[1]) it doesn't seem to work...
Well, I meant *after* strsplit: temp <- strsplit(foo, "") L <- lapply(temp, function(x) x[1]) as.numeric(unlist(L)) In this case you can also calculate it: floor(foo / (10^floor(log(foo, 10)))) Uwe Ligges -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._