K. Elo wrote: > Hi, > > I am quite new to R (but like it very much!), so please apologize if > this is a too simple question. > > I have a large data frame consisting of data from a survey. There is, > for example, information about age and education (a numeric value from > 1-9). Now I would like to extract the total amount of each type of > education within different age groups (e.g. from 18 to 25, from 25 to > 35 etc.). How could I achieve this? (I have been thinking about > using 'subset', but if there are better ideas they are welcome :) ) > > An example might clarify my point. Let's assume the following data: > # age edu > 1 25 2 > 2 33 5 > 3 22 3 > 4 19 1 > 5 21 3 > 6 30 4 > 7 32 4 > 8 31 1 > > What I want to have is: > > edu 18-25 25-35 ... > 1 1 1 > 2 1 0 > 3 2 0 > 4 0 2 > 5 0 1 > > Thanks in advance& kind regards, > Kimmo
See ?cut which will enable you to take a continuous vector and convert it into a factor based upon breakpoints. Use this combined with ?table which will give you a cross tabulation. Something along the lines of the following, presuming that your data is in a data frame called 'DF': > with(DF, table(edu, cut(age, breaks = c(18, 25, 35)))) edu (18,25] (25,35] 1 1 1 2 1 0 3 2 0 4 0 2 5 0 1 Note the default symbology of the returned labels indicating whether or not the interval breakpoints are open or closed in each grouping. This is covered in the help for cut(). Pay attention to the 'include.lowest' and 'right' arguments. Note also the 'trick' of using with() here, so that the column names are evaluated within the *environment* of the dataframe. See ?with for more information there. HTH, Marc Schwartz ______________________________________________ R-help@r-project.org mailing list 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.
