How to delete multiple values from a vector

Question

I have a vector like  a   c 1 10  and I need to remove multiple values  like  2  3  5  How to delete those numbers  they are NOT the positions in the vector  in the vector   at the moment i loop the vector and do something like    a  a NUMBER TO REMOVE    But I think there is a function that does it automatically

User · Answer

You can do it as follows    gt  x lt -c 2  4  6  9  10    the list  gt  y lt -c 4  9  10    values to be removed   gt  idx   which x  in  y     Positions of the values of y in x  gt  idx  1  2 4 5  gt  x   x -idx    Remove those values using their position and  -  operator  gt  x  1  2 6   Shortly   gt  x   x  - which x  in  y

User · Answer

instead of   x  lt - x   x  in  c 2 3 5     using the packages purrr and magrittr  you can do   your vector   lt  gt   discard    x  in  c 2 3 5     this allows for subsetting using the vector name only once  And you can use it in pipes

User · Answer

There is also subset which might be useful sometimes   a  lt - sample 1 10  bad  lt - c 2  3  5    gt  subset a    a  in  bad    1   9  7 10  6  8  1  4

User · Answer

The  in  operator tells you which elements are among the numers to remove    gt  a  lt - sample  1   10   gt  remove  lt - c  2  3  5   gt  a   1  10  5  2  7  1  6  3  4  8  9  gt  a  in  remove   1  FALSE  TRUE  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  gt  a    a  in  remove    1  10  7  1  6  4  8  9   Note that this will silently remove incomparables  stuff like NA or Inf  as well  while it will keep duplicate values in a as long as they are not listed in remove      If a can contain incomparables  but remove will not  we can use match  telling it to return 0 for non-matches and incomparables   in  is a conventient shortcut for match     gt  a  lt - c  a  NA  Inf   gt  a   1   10   5   2   7   1   6   3   4   8   9  NA Inf  gt  match  a  remove  nomatch   0L  incomparables   0L    1  0 3 1 0 0 0 2 0 0 0 0 0  gt  a  match  a  remove  nomatch   0L  incomparables   0L     0L   1   10   7   1   6   4   8   9  NA Inf   incomparables   0 is not needed as incomparables will anyways not match  but I d include it for the sake of readability  This is  btw   what setdiff does internally  but without the unique to throw away duplicates in a which are not in remove   If remove contains incomparables  you ll have to check for them individually  e g   if  any  is na  remove       a  lt - a    is na  a      This does not distinguish NA from NaN but the R manual anyways warns that one should not rely on having a difference between them   For Inf  -Inf you ll have to check both sign and is finite

User · Answer

UPDATE   All of the above answers won t work for the repeated values   BenBolker s answer using duplicated   predicate solves this   full vector  full vector  in  searched vector   duplicated full vector     Original Answer   here I write a little function for this   exclude val lt -function full vector searched vector          found c          for i in full vector              if any is element searched vector i               searched vector  which searched vector  i   1   NA                   else            found c found i                       return found      so  let s say full vector c 1 2 3 4 1  and searched vector c 1 2 3     exclude val full vector searched vector  will return  4 1   however above answers will return just  4

User · Answer

You can use setdiff   Given  a  lt - sample 1 10  remove  lt - c 2  3  5    Then   gt  a   1  10  8  9  1  3  4  6  7  2  5  gt  setdiff a  remove   1  10  8  9  1  4  6  7

User · Answer

q  lt - c 1 1 2 2 3 3 3 4 4 5 5 7 7  rm  lt - q 11  remove rm  q q 13    NaN q q  in  7   This sets the 13 in a vector to not a number NAN  it shows false remove q c 11 12 13    if you try this you will see that remove function don t work on vector number  you remove entire vector but maybe not a single element

User · Answer

First we can define a new operator     ni     Negate    in       Then  its like x not in remove   x  lt - 1 10 remove  lt - c 2 3 5  x  lt - x  x  ni  remove     or why to go for remove  go directly    x  lt - x  x  ni  c 2 3 5

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