> 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
Read the documentation more closely: sapply(dataFrame, func)
applies func() to each column, not row, of dataFrame.
> preferences <- sapply(df, evaluate.questions, function(x,y,z)
> evaluate.questions(df['Q1'],df['Q2'],df['Q3']))
Furthermore,
sapply(X = dataFrame, FUN = func, extraArgument)
calls
func(dataFrame[, i], extraArgument)
for i in seq_len(ncol(dataFrame).
One problem is that FUN=evaluate.questions takes 3 arguments and
you give it only 2. Another problem is that the third argument you
pass to sapply is a function (of 3 arguments) and FUN is not expecting
any of its arguments to be functions.
It may be easier for you to not use sapply here, but to use for-loops and
come up with something that works. (Write tests that will indicate whether
it works or not in a variety of situations.) Then transform it to use things
like ifelse() and sapply() to make it more readable and run faster.
> 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?
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of Walter Anderson
> Sent: Friday, December 06, 2013 7:44 AM
> 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.
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
