[R] [FORGED] Re: remove

[Rolf Turner]

On 12/02/17 18:36, Bert Gunter wrote:
> Basic stuff!
>
> Either subscripting or ?subset.
>
> There are many good R tutorials on the web. You should spend some
> (more?) time with some.

Uh, Bert, perhaps I'm being obtuse (a common occurrence) but it doesn't 
seem basic to me.  The only way that I can see how to go at it is via
a for loop:

rdln <- function(X) {
# Remove discordant last names.
     ok <- logical(nrow(X))
     for(nm in unique(X$first)) {
         xxx <- unique(X$last[X$first==nm])
         if(length(xxx)==1) ok[X$first==nm] <- TRUE
     }
     Y <- X[ok,]
     Y <- Y[order(Y$first),]
     rownames(Y) <- 1:nrow(Y)
     Y
}

Calling the toy data frame "melvin" rather than "df" (since "df" is the 
name of the built in F density function, it is bad form to use it as the 
name of another object) I get:

 > rdln(melvin)
   first week last
1   Bob    1 John
2   Bob    2 John
3   Bob    3 John
4  Cory    1 Jack
5  Cory    2 Jack

which is the desired output.  If there is a "basic stuff" way to do this
I'd like to see it.  Perhaps I will then be toadally embarrassed, but 
they say that this is good for one.

cheers,

Rolf

-- 
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276

> On Sat, Feb 11, 2017 at 9:02 PM, Val <valkremk at gmail.com> wrote:
>> Hi all,
>> I have a big data set and want to  remove rows conditionally.
>> In my data file  each person were recorded  for several weeks. Somehow
>> during the recording periods, their last name was misreported.   For
>> each person,   the last name should be the same. Otherwise remove from
>> the data. Example, in the following data set, Alex was found to have
>> two last names .
>>
>> Alex   West
>> Alex   Joseph
>>
>> Alex should be removed  from the data.  if this happens then I want
>> remove  all rows with Alex. Here is my data set
>>
>> df <- read.table(header=TRUE, text='first  week last
>> Alex    1  West
>> Bob     1  John
>> Cory    1  Jack
>> Cory    2  Jack
>> Bob     2  John
>> Bob     3  John
>> Alex    2  Joseph
>> Alex    3  West
>> Alex    4  West ')
>>
>> Desired output
>>
>>       first  week last
>> 1     Bob     1   John
>> 2     Bob     2   John
>> 3     Bob     3   John
>> 4     Cory     1   Jack
>> 5     Cory     2   Jack