[R] Using if, else statements

[Patrick Burns]

jjdow <- sample(c('Sun', 'Mon', 'Tues'), 10, replace=TRUE)
jjdata <- data.frame(admission=1:10, d.o.w.=jjdow)

#> jjdata
#   admission d.o.w.
#1          1   Tues
#2          2   Tues
#3          3   Tues
#4          4    Sun
#5          5    Mon
#6          6    Mon
#7          7    Sun
#8          8   Tues
#9          9    Sun
#10        10    Mon

new.jjdata <- within(jjdata, admission <- ifelse(d.o.w. == 'Sun',
    1.21 * admission, ifelse(d.o.w.=='Mon', .91 * admission, admission)))

#> new.jjdata
#   admission d.o.w.
#1       1.00   Tues
#2       2.00   Tues
#3       3.00   Tues
#4       4.84    Sun
#5       4.55    Mon
#6       5.46    Mon
#7       8.47    Sun
#8       8.00   Tues
#9      10.89    Sun
#10      9.10    Mon

Pat


Robin Williams wrote:
> No, this is my first experience with any powerful statistical package. Any
> code much appreciated.
>
> -----Original Message-----
> From: Patrick Burns [mailto:pburns at pburns.seanet.com] 
> Sent: 23 July 2008 17:44
> To: Robin Williams
> Subject: Re: [R] Using if, else statements
>
> You might have found 'ifelse' in S Poetry, which
> is one way of solving your problem.
>
>
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of S Poetry and "A Guide for the Unwilling S User")
>
> Robin Williams wrote:
>   
>> Hi all, 
>>
>> Again I have searched the net and so on, without finding an answer to this
>> surely simple problem. A short bit of code would be appreciated. 
>>
>>   I have a object named `data' with the following column headings.
>>
>> Date, maxitemp, minitemp, admissions, d.o.w.
>>
>> Where d.o.w. is day of the week, written "Sun" "Mon" etc.
>>
>>   I just need to scale the Monday admissions by 0.91, the Saturday
>> admissions by 1.21 and the Sunday admissions by 1.22. So basically what I
>> want is:
>>
>> If d.o.w. == "Sat" 
>>
>> Multiply Sat admissions by 1.21.
>>
>> (Now do I need an else statement here, or can I just do another)
>>
>> If d.o.w. == "Sun" 
>>
>> Multiply "Sun" admissions by 1.22
>>
>> (and finally)
>>
>> If d.o.w. == "Mon" 
>>
>> Multiply Monday admissions by 0.91. 
>>
>> Else do nothing. 
>>
>>   I assume in my code I need to specify that I am using the data.frame
>> `data', so do I need to write things like 
>>
>> If(data[d.o.w.]=="Mon")  
>>
>>   I would then like to round the new admissions to integers (I assume I
>>     
> just
>   
>> use round(data$admissions)), and output the new data to another csv file. 
>>
>>   I could of course do this in excel but I will need to extend this type
>>     
> of
>   
>> idea in the future so I would like to master it in R. 
>>
>> Many thanks for any help/code.
>>
>> Robin Williams.  
>>
>>
>> 	[[alternative HTML version deleted]]
>>
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>>     
> http://www.R-project.org/posting-guide.html
>   
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>>   
>>     
>
>
>
>