[R] is this a bug?

[(Ted Harding)]

And the extra twist in the tale is exemplified by this
mini-version of Albert-Jan's first example:

  DF <- data.frame(A=c(1,2,3))
  DF$B <- c(4,5,6)
  DF$C <- c(7,8,9)
  DF
  #   A B C
  # 1 1 4 7
  # 2 2 5 8
  # 3 3 6 9

  DF$D <- DF["A"]/DF["B"]
  DF
  #   A B C    A
  # 1 1 4 7 0.25
  # 2 2 5 8 0.40
  # 3 3 6 9 0.50

##And why:

  DF["A"]/DF["B"]
  #      A
  # 1 0.25
  # 2 0.40
  # 3 0.50

##So the ratio DF["A"]/DF["B"] comes out with the name of
##the numerator, "A". This is then the name given to DF$D

Thus Albert-Jan's
  df["weight"] / ave(df["weight"], df["sex"], FUN=sum)*100
comes through with name "weight".

Ted.


On 17-Jun-11 21:06:42, William Dunlap wrote:
> df$varname is a column of df.
> 
> df["varname"] is a one-column df containing that column.
> 
> df[["varname"]] is a column of df (same as df$varname).
> 
> df[,"varname"] is a column of df (same as df$varname).
> 
> df[,"varname",drop=FALSE] is a one-column df (same as df$varname).
> 
> df$newVarname <- df["varname"] inserts a new component
> into df, the component being a one-column data.frame,
> not the column in that data.frame.
> 
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com  
> 
>> -----Original Message-----
>> From: r-help-bounces at r-project.org 
>> [mailto:r-help-bounces at r-project.org] On Behalf Of Albert-Jan Roskam
>> Sent: Friday, June 17, 2011 1:49 PM
>> To: R Mailing List
>> Subject: [R] is this a bug?
>> 
>> Hello,
>> 
>> Is the following a bug? I always thought that df$varname <- 
>> does the same as 
>> df["varname"] <-
>> 
>> > df <- data.frame(weight=round(runif(10, 10, 100)), 
>> sex=round(runif(100, 0, 
>> 1)))
>> > df$pct <- df["weight"] / ave(df["weight"], df["sex"], FUN=sum)*100
>> > names(df)
>> [1] "weight" "sex"    "pct"     ### ----------> ok
>> > head(df)
>>   weight sex    weight  ### ----------> huh!?!
>> 1     86   0 2.4002233
>> 2     19   1 0.5643006
>> 3     32   0 0.8931063
>> 4     87   0 2.4281328
>> 5     45   0 1.2559308
>> 6     95   0 2.6514094
>> > rm(df)
>> > df <- data.frame(weight=round(runif(10, 10, 100)), 
>> sex=round(runif(100, 0, 
>> 1)))
>> > df["pct"] <- df["weight"] / ave(df["weight"], df["sex"], 
>> FUN=sum)*100 ### 
>> >-----> this does work
>> > names(df)
>> [1] "weight" "sex"    "pct"   
>> > head(df)
>>   weight sex       pct
>> 1     15   0 0.5246590
>> 2     43   0 1.5040224
>> 3     17   1 0.9284544
>> 4     44   1 2.4030584
>> 5     76   1 4.1507373
>> 6     59   0 2.0636586
>> > do.call(c, R.Version())
>>                        platform                            arch 
>>             "i686-pc-linux-gnu"                          "i686" 
>>                              os                          system 
>>                     "linux-gnu"               "i686, linux-gnu" 
>>                          status                           major 
>>                              ""                             "2" 
>>                           minor                            year 
>>                          "11.1"                          "2010" 
>>                           month                             day 
>>                            "05"                            "31" 
>>                         svn rev                        language 
>>                         "52157"                             "R" 
>>                  version.string 
>> "R version 2.11.1 (2010-05-31)" 
>> > # Thanks!
>> 
>> Cheers!!
>> Albert-Jan
>> 
>> 
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> All right, but apart from the sanitation, the medicine, 
>> education, wine, public 
>> order, irrigation, roads, a fresh water system, and public 
>> health, what have the 
>> Romans ever done for us?
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>>      [[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.
>> 
> 
> ______________________________________________
> 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.

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E-Mail: (Ted Harding) <ted.harding at wlandres.net>
Fax-to-email: +44 (0)870 094 0861
Date: 17-Jun-11                                       Time: 22:24:41
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