[R] remove

[P Tennant]

Hi Val,

The by() function could be used here. With the dataframe dfr:

# split the data by first name and check for more than one last name for 
each first name
res <- by(dfr, dfr['first'], function(x) length(unique(x$last)) > 1)
# make the result more easily manipulated
res <- as.table(res)
res
# first
  # Alex   Bob  Cory
  # TRUE FALSE FALSE

# then use this result to subset the data
nw.dfr <- dfr[!dfr$first %in% names(res[res]) , ]
# sort if needed
nw.dfr[order(nw.dfr$first) , ]

   first week last
2   Bob    1 John
5   Bob    2 John
6   Bob    3 John
3  Cory    1 Jack
4  Cory    2 Jack


Philip

On 12/02/2017 4:02 PM, Val 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
>
> Thank you in advance
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.