[R] Error in combined for() and if() code

[Duncan Murdoch]

On 28/12/2010 1:13 PM, Uwe Ligges wrote:
>
>
> On 28.12.2010 19:08, Nathan Miller wrote:
>> Hello,
>>
>> I am trying to filter a data set like below so that the peaks in the Phase
>> value are more obvious and can be identified by a peak finding function
>> following the useful advise of Carl Witthoft. I have written the following
>>
>> for(i in length(data$Phase)){
>
> Nonsense: In this case the loop will only run once for i=length(data$Phase)

Yes, I missed that.

>
> you probably want
>
> for(i in seq_along(data$Phase)){
>
>
>> newphase=if(abs(data$Phase[i+1]-data$Phase[i])>6){
>
> Nonsense:
> 1. if()... won't return any useful result.

if (cond) v1 else v2

does return a value (either v1 or v2).  So the construction

newphase = if (abs(data$Phase[i+1] ....

will set newphase to a new value each time through the loop.  That's 
probably not what was intended...

> 2. i+1 is not within your data

That's the only one I saw.

Duncan Murdoch

>
> Uwe Ligges
>
>
>> data$Phase[i+1]
>> }else{data$Phase[i]
>> }
>> }
>>
>> I get the following error which I have not seen before when I paste the code
>> into R
>>
>> Error in if (abs(data$Phase[i + 1] - data$Phase[i])>   6) { :
>>     missing value where TRUE/FALSE needed
>>
>> I don't have much experience with such loops as I have tried to avoid using
>> them in the past. Can anyone identify the error(s) in the code I have
>> written or a simpler means of writing such a filter?
>>
>> Thank you,
>> Nate
>>
>>
>> data=
>>       Time Phase
>> 1  0.000 15.18
>> 2  0.017 13.42
>> 3  0.034 11.40
>> 4  0.051 18.31
>> 5  0.068 25.23
>> 6  0.085 33.92
>> 7  0.102 42.86
>> 8  0.119 42.87
>> 9  0.136 42.88
>> 10 0.153 42.88
>> 11 0.170 42.87
>> 12 0.186 42.88
>> 13 0.203 42.88
>> 14 0.220 42.78
>> 15 0.237 33.50
>> 16 0.254 24.81
>> 17 0.271 17.20
>> 18 0.288 10.39
>> 19 0.305 13.97
>> 20 0.322 16.48
>> 21 0.339 14.75
>> 22 0.356 20.80
>> 23 0.373 25.79
>> 24 0.390 31.25
>> 25 0.407 39.89
>> 26 0.423 40.04
>> 27 0.440 40.05
>> 28 0.457 40.05
>> 29 0.474 40.05
>> 30 0.491 40.05
>> 31 0.508 40.06
>> 32 0.525 40.07
>> 33 0.542 32.23
>> 34 0.559 23.90
>> 35 0.576 17.86
>> 36 0.592 11.63
>> 37 0.609 12.78
>> 38 0.626 13.12
>> 39 0.643 10.93
>> 40 0.660 10.63
>> 41 0.677 10.82
>> 42 0.694 11.84
>> 43 0.711 20.44
>> 44 0.728 27.33
>> 45 0.745 34.22
>> 46 0.762 41.55
>> 47 0.779 41.55
>> 48 0.796 41.55
>> 49 0.813 41.53
>> 50 0.830 41.53
>> 51 0.847 41.52
>> 52 0.864 41.52
>> 53 0.880 41.53
>> 54 0.897 41.53
>> 55 0.914 33.07
>> 56 0.931 25.12
>> 57 0.948 19.25
>> 58 0.965 11.30
>> 59 0.982 12.48
>> 60 0.999 13.85
>> 61 1.016 13.62
>> 62 1.033 12.62
>> 63 1.050 19.39
>> 64 1.067 25.48
>> 65 1.084 31.06
>> 66 1.101 39.49
>> 67 1.118 39.48
>> 68 1.135 39.46
>> 69 1.152 39.45
>> 70 1.169 39.43
>> 71 1.185 39.42
>> 72 1.202 39.42
>> 73 1.219 39.41
>> 74 1.236 39.41
>> 75 1.253 37.39
>> 76 1.270 29.03
>> 77 1.287 20.61
>> 78 1.304 14.07
>> 79 1.321  9.12
>>
>> 	[[alternative HTML version deleted]]
>>
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>
> ______________________________________________
> R-help at 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.