Hi The warning is due to fact that "if" takes only single scalar value not an entire vector.
Maybe you shall explain more clearly what result do you expect. I bet that there is vectorised solution to your problem but I am lost in your ifs and cannot follow what shall be the output. Please use dput(head(df)) when showing input data and clearly describe intended result. Regards Petr > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Walter Anderson > Sent: Friday, December 06, 2013 4:44 PM > To: r-help@r-project.org > Subject: [R] Need help figuring out sapply (and similar functions) with > multiple parameter user defined function > > I am having trouble understanding how to use sapply (or similar > functions) with a user defined function with multiple parameters. > > I have the following functions defined > > q1.ans <- function(x) > { > retVal = 0 > if (x == 1) { > retVal = 1 > } else if (x ==2) { > retVal = 2 > } > return (retVal) > } > q2.ans <- function(x) > { > retVal = 0 > if (x == 1) { > retVal = 1 > } else if (x ==2) { > retVal = 3 > } > return (retVal) > } > q3.ans <- function(x) > { > retVal = 0 > if (x == 1) { > retVal = 2 > } else if (x ==2) { > retVal = 3 > } > return (retVal) > } > > evaluate.questions <- function(q.1,q.2,q.3) > { > a <- q1.ans(q.1) > b <- q2.ans(q.2) > c <- q3.ans(q.3) > retVal = 0 # Set default value to be no preference > # The following code only implements those values from the state > machine that show a preference (ID's 5,9,11,13-15,17-18,21,23-27) > if (a == 0) { > if (b == 1) { > if (c == 1) { > retVal = 1 # State machine ID 5 > } > } else if (b == 2) { > if (c == 2) { > retVal = 2 # State machine ID 9 > } > } > } else if (a == 1) { > if (b == 0) { > if (c == 1) { > retVal = 1 # State machine ID 11 > } > } else if (b == 1) { > retVal = 1 # State machine ID's 13-15, value of C doesn't > matter > } else if (b == 2) { > if (c == 1) { > retVal = 1 # State machine ID 17 > } else if (c == 2) { > retVal = 2 # State machine ID 18 > } > } > } else if (a == 2) { > if (b == 0) { > if (c == 2) { > retVal = 2 # State machine ID 21 > } > } else if (b == 1) { > if (c == 1) { > retVal = 1 # State machine ID 23 > } else if (c == 2) { > retVal = 2 # State machine ID 24 > } > } else if (b == 2) { > retVal = 2 # State machine ID's 25-27, value of C doesn't > matter > } > } > return (retVal) > } > > And a data set that looks like this: > > ID,Q1,Q2,Q3 > 1,2,2,2 > 2,2,1,1 > 3,1,1,1 > 4,1,2,2 > 5,2,2,1 > 6,1,2,1 > ... > > > I have been researching and it appears that I should be using the > sapply function to apply the evaluate.question function above to each > row in the data frame like this > > preferences <- sapply(df, evaluate.questions, function(x,y,z) > evaluate.questions(df['Q1'],df['Q2'],df['Q3'])) > > Unfortunately this doesn't work and the problem appears that the sapply > function is not feeding the parameters to the evaluate.questions > function as I expect. Can someone provide some guidance on what I am > doing wrong? > > This is the error message I am getting: > > Error in x --1 : > Comparison (1) is possible only for atomic and list types In > addition: warning messages: > In if (x == 1) { : > the condition has length > 1 and only the first element will be used > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. ______________________________________________ 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.
