[R] If else loop problem: the condition has length > 1 and only the first element will be used

[arun]

HI,

It may be better to provide an example dataset using ?dput().
dput(head(dataset),20)

Try:
signal3<- ifelse(t.tr=="Pst 24", signal2-17.29, ifelse(t.tr=="Pst 48", signal2 - 43.93256, etc.....)) 


A.K.

----- Original Message -----
From: "Fethe, Michael" <mfethe1 at utk.edu>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc: 
Sent: Sunday, August 25, 2013 9:31 PM
Subject: [R] If else loop problem: the condition has length > 1 and only the first element will be used

Hi all,

I'm running an if else loop to normalize my data to a known control.
I have calculated values that need to be subtracted from each treatment applied. I'm trying this within a for loop with if and else commands to apply to correct subtraction. This is done as follows:


attach(data.2013)

#Normalize to known control

for(i in signal2) {

if(t.tr=="Pst 24") {signal3=(signal2 - 17.29)}

if(t.tr=="Pst 48") {signal3=(signal2 - 43.93256)}

if(t.tr=="Pst 72") {signal3=(signal2 - 43.477468)}

if(t.tr=="Pto 24") {signal3=(signal2 - 29.39875)}

if(t.tr=="Pto 48") {signal3=(signal2 - 76.796645)}

if(t.tr=="Pto 72") {signal3=(signal2 - 68.176174)}

if(t.tr=="Pm 24") {signal3=(signal2 + 0.498333)}

if(t.tr=="Pm 48") {signal3=(signal2 - 0.200417)}

if(t.tr=="Pm 72") {signal3=(signal2 - 10.465507)}

else {signal3=signal2}

}


This code ran once with no problems or warnings. Now it produces a ton of warnings of

"the condition has length > 1 and only the first element will be used".


Here is str(data.2013)


'data.frame': 4293 obs. of  8 variables:

$ rep      : Factor w/ 4 levels "R1","R2","R3",..: 1 1 1 1 1 1 1 1 1 1 ...

$ construct: Factor w/ 10 levels "35S","46S","E1",..: 1 1 1 1 1 1 1 1 1 1 ...

$ time     : int  24 24 24 24 24 24 24 24 24 24 ...

$ treatment: Factor w/ 8 levels "Mock","MockUN",..: 1 1 1 1 1 1 2 2 2 3 ...

$ sample   : int  1 2 3 4 5 6 1 2 3 1 ...

$ signal   : int  733750 665790 659550 676270 682770 600420 676350 652110 665350 798850 ...

$ signal2  : num  734 666 660 676 683 ...

$ t.tr     : Factor w/ 24 levels "Mock 24","Mock 48",..: 1 1 1 1 1 1 4 4 4 7 ...



I'm really not sure why this ran once and now is giving me errors.

Can anyone help? I've heard ifelse can be effective when running into this error. However, this command does not function the way i would like. I need a specific value subtracted from each treatment/time value. The only value that should matter for subtracting the correct value is t.tr.



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