R help - Aug 2014 - Unexpected behavior when giving a value to a new variable based on the value of another variable

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]]

You are being bitten by the "partial matching" of the "$"
operator
(see  ?"$" for a better explanation).  Here is solution that works:


**original**
> 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
>
>
> 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  # use the '[['
operation for complete matching
> N
  age samplem sample
1  67      NA      1
2  62       1     NA
3  74       1      1
4  61       1     NA
5  60       1     NA
6  55       1     NA
7  60       1     NA
8  59       1     NA
9  58      NA     NA

Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.


On Fri, Aug 29, 2014 at 4:53 AM, 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]]
>
> ______________________________________________
> 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.

On Fri, Aug 29, 2014 at 3:53 AM, 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:
>
>
<snip>
>
> Any clue for this behavior?
>
<snip>
>
> Thank you very much.
>
> Angel Rodriguez-Laso
> Research project manager
> Matia Instituto Gerontologico
That is unusual, but appears to be documented in a section from

?`[`

<quote>
Character indices

Character indices can in some circumstances be partially matched (see
pmatch) to the names or dimnames of the object being subsetted (but
never for subassignment). Unlike S (Becker et al p. 358)), R never
uses partial matching when extracting by [, and partial matching is
not by default used by [[ (see argument exact).

Thus the default behaviour is to use partial matching only when
extracting from recursive objects (except environments) by $. Even in
that case, warnings can be switched on by
options(warnPartialMatchDollar = TRUE).

Neither empty ("") nor NA indices match any names, not even empty nor
missing names. If any object has no names or appropriate dimnames,
they are taken as all "" and so match nothing.
</quote>

Note the commend about "partial matching" in the middle paragraph in
the quote above.

-- 
There is nothing more pleasant than traveling and meeting new people!
Genghis Khan

Maranatha! <><
John McKown

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.
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live
Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
--------------------------------------------------------------------------- 
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]]
>
>______________________________________________
>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.