You may want to consider another way of getting your answer that takes advantage of some of R's features:
> # Make some example data > cods <- LETTERS[1:10] # Ten companies > yrs <- 2010:2014 # 5 years > set.seed(42) # Set random seed so we all get the same values > # Chances of revenue for a given year are 95% > rev <- round(rbinom(50, 1, .95)*runif(50, 25, 50), 2) > z <- data.frame(expand.grid(year=yrs, cod=cods)[, 2:1], rev) > # Remove years with missing (0) revenue > z <- z[z$rev > 1, ] > str(z) 'data.frame': 45 obs. of 3 variables: $ cod : Factor w/ 10 levels "A","B","C","D",..: 1 1 1 1 1 2 2 2 2 2 ... $ year: int 2010 2011 2012 2013 2014 2010 2011 2012 2013 2014 ... $ rev : num 33.3 33.7 35 44.6 26 ... > > # Construct the dummy variable > tbl <- xtabs(~cod+year, z) > tbl year cod 2010 2011 2012 2013 2014 A 1 1 1 1 1 B 1 1 1 1 1 C 1 1 1 1 1 D 1 0 1 1 1 E 1 1 0 1 1 F 1 1 1 1 1 G 1 1 1 1 1 H 1 1 1 1 1 I 1 1 1 0 1 J 0 1 1 0 1 > dummy <- as.integer(apply(tbl, 1, all)) > dummy [1] 1 1 1 0 0 1 1 1 0 0 ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Michael Dewey Sent: Wednesday, June 24, 2015 2:12 PM To: giacomo begnis; r-help@r-project.org Subject: Re: [R] create a dummy variables for companies with complete history. Comments below On 24/06/2015 19:26, giacomo begnis wrote: > Hi, I have a dataset (728 obs) containing three variables code of a company, > year and revenue. Some companies have a complete history of 5 years, others > have not a complete history (for instance observations for three or four > years).I would like to determine the companies with a complete history using > a dummy variables.I have written the following program but there is somehting > wrong because the dummy variable that I have create is always equal to > zero.Can somebody help me?Thanks, gm > > z<-read.table(file="c:/Rp/cddat.txt", sep="", header=T) > attach(z) > n<-length(z$cod) // number of obs dataset > Could also use nrow(z) > d1<-numeric(n) // dummy variable > > for (i in 5:n) { > if (z$cod[i]==z$cod[i-4]) // cod is the code of a company { d1[i]<=1} else { d1[i]<=0} // d1=1 for a company with complete history, d1=0 if the history is not complete }d1 Did you really type <= which means less than or equals to? If so, try replacing it with <- and see what happens. > When I run the program d1 is always equal to zero. Why? > Once I have create the dummy variable with subset I obtains the code of the > companies with a complete history and finally with a merge I determine a > panel of companies with a complete history.But how to determine correctly > d1?My best regards, gm > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Michael http://www.dewey.myzen.co.uk/home.html ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
