[R] Unexpected behavior when giving a value to a new variable based on the value of another variable

[Jeff Newmiller]

One clue is the help file for "$"...

?" $"

In particular there see the discussion of character indices and the "exact" argument.

You can also find this discussed in the Introduction to R document that comes with the software.
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Sent from my phone. Please excuse my brevity.

On August 29, 2014 1:53:47 AM PDT, Angel Rodriguez <angel.rodriguez at matiainstituto.net> wrote:
>
>Dear subscribers,
>
>I've found that if there is a variable in the dataframe with a name
>very similar to a new variable, R does not give the correct values to
>this latter variable based on the values of a third value:
>
>
>> M <- structure(list(V1 = c(67, 62, 74, 61, 60, 55, 60, 59,
>58)),.Names = c("age"), row.names = c(NA, -9L), 
>+                class = "data.frame")
>> M$sample[M$age >= 65] <- 1 
>> M
>  age sample
>1  67      1
>2  62     NA
>3  74      1
>4  61     NA
>5  60     NA
>6  55     NA
>7  60     NA
>8  59     NA
>9  58     NA
>> N <- structure(list(V1 = c(67, 62, 74, 61, 60, 55, 60, 59, 58), V2 =
>c(NA, 1, 1, 1, 1,1,1,1,NA)), 
>+                     .Names = c("age","samplem"), row.names = c(NA,
>-9L), class = "data.frame")
>> N$sample[N$age >= 65] <- 1 
>> N
>  age samplem sample
>1  67      NA      1
>2  62       1      1
>3  74       1      1
>4  61       1      1
>5  60       1      1
>6  55       1      1
>7  60       1      1
>8  59       1      1
>9  58      NA     NA
>
>
>
>Any clue for this behavior?
>
>
>
>My specifications:
>
>R version 3.1.1 (2014-07-10)
>Platform: x86_64-w64-mingw32/x64 (64-bit)
>
>locale:
>[1] LC_COLLATE=Spanish_Spain.1252  LC_CTYPE=Spanish_Spain.1252   
>LC_MONETARY=Spanish_Spain.1252
>[4] LC_NUMERIC=C                   LC_TIME=Spanish_Spain.1252    
>
>attached base packages:
>[1] stats     graphics  grDevices utils     datasets  methods   base   
> 
>
>other attached packages:
>[1] foreign_0.8-61
>
>loaded via a namespace (and not attached):
>[1] tools_3.1.1
>
>
>
>
>Thank you very much.
>
>Angel Rodriguez-Laso
>Research project manager
>Matia Instituto Gerontologico
>
>
>	[[alternative HTML version deleted]]
>
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