Filter multiple values on a string column in dplyr

Question

I have a data frame with character data in one of the columns  I would like to filter multiple options in the data frame from the same column  Is there an easy way to do this that I m missing   Example  data frame name   dat  days      name 88        Lynn 11          Tom 2           Chris 5           Lisa 22        Kyla 1          Tom 222      Lynn 2         Lynn   I d like to filter out Tom and Lynn for example  When I do   target  lt - c  Tom    Lynn   filt  lt - filter dat  name    target    I get  this error   longer object length is not a multiple of shorter object length

User · Answer

This can be achieved using dplyr package, which is available in CRAN. The simple way to achieve this:

Install dplyr package.
Run the below code

library(dplyr) 

df<- select(filter(dat,name=='tom'| name=='Lynn'), c('days','name))

Explanation:

So, once we’ve downloaded dplyr, we create a new data frame by using two different functions from this package:

filter: the first argument is the data frame; the second argument is the condition by which we want it subsetted. The result is the entire data frame with only the rows we wanted. select: the first argument is the data frame; the second argument is the names of the columns we want selected from it. We don’t have to use the names() function, and we don’t even have to use quotation marks. We simply list the column names as objects.

User · Answer

by type year tag filtered  lt - by type year tag   gt         dplyr   filter tag name  in  c  dplyr    ggplot2

User · Answer

Using the base package   df  lt - data frame days   c 88  11  2  5  22  1  222  2   name   c  Lynn    Tom    Chris    Lisa    Kyla    Tom    Lynn    Lynn       Three lines target  lt - c  Tom    Lynn   index  lt - df name  in  target df index       One line df df name  in  c  Tom    Lynn         Output     days name 1   88 Lynn 2   11  Tom 6    1  Tom 7  222 Lynn 8    2 Lynn   Using sqldf   library sqldf    Two alternatives  sqldf  SELECT         FROM df        WHERE name    Tom  OR name    Lynn    sqldf  SELECT         FROM df        WHERE name IN   Tom    Lynn

User · Answer

You need  in  instead of      library dplyr  target  lt - c  Tom    Lynn   filter dat  name  in  target     equivalently  dat   gt   filter name  in  target    Produces    days name 1   88 Lynn 2   11  Tom 3    1  Tom 4  222 Lynn 5    2 Lynn   To understand why  consider what happens here   dat name    target    1  FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE   Basically  we re recycling the two length target vector four times to match the length of dat name   In other words  we are doing    Lynn    Tom   Tom    Lynn Chris    Tom  Lisa    Lynn      continue repeating Tom and Lynn until end of data frame   In this case we don t get an error because I suspect your data frame actually has a different number of rows that don t allow recycling  but the sample you provide does  8 rows    If the sample had had an odd number of rows I would have gotten the same error as you   But even when recycling works  this is clearly not what you want   Basically  the statement dat name    target is equivalent to saying      return TRUE for every odd value that is equal to  Tom  or every even value that is equal to  Lynn     It so happens that the last value in your sample data frame is even and equal to  Lynn   hence the one TRUE above   To contrast  dat name  in  target says      for each value in dat name  check that it exists in target    Very different   Here is the result    1   TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE   Note your problem has nothing to do with dplyr  just the mis-use of

[r] Filter multiple values on a string column in dplyr

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