What does mean in R

Question

I am following this example  the server R  file is here   I plan to do a similar filter  but am lost as to what   gt   does      Apply filters     m  lt - all movies   gt         filter          Reviews  gt   reviews          Oscars  gt   oscars          Year  gt   minyear          Year  lt   maxyear          BoxOffice  gt   minboxoffice          BoxOffice  lt   maxboxoffice           gt         arrange Oscars

User · Answer

Use        to get the documentation       is matrix multiplication   For matrix multiplication  you need an m x n matrix times an n x p matrix

User · Answer

The infix operator   gt   is not part of base R  but is in fact defined by the package magrittr  CRAN  and is heavily used by dplyr  CRAN    It works like a pipe  hence the reference to Magritte s famous painting The Treachery of Images   What the function does is to pass the left hand side of the operator to the first argument of the right hand side of the operator  In the following example  the data frame iris gets passed to head     library magrittr  iris   gt   head     Sepal Length Sepal Width Petal Length Petal Width Species 1          5 1         3 5          1 4         0 2  setosa 2          4 9         3 0          1 4         0 2  setosa 3          4 7         3 2          1 3         0 2  setosa 4          4 6         3 1          1 5         0 2  setosa 5          5 0         3 6          1 4         0 2  setosa 6          5 4         3 9          1 7         0 4  setosa   Thus  iris   gt   head   is equivalent to head iris    Often    gt   is called multiple times to  chain  functions together  which accomplishes the same result as nesting  For example in the chain below  iris is passed to head    then the result of that is passed to summary     iris   gt   head     gt   summary     Thus iris   gt   head     gt   summary   is equivalent to summary head iris    Some people prefer chaining to nesting because the functions applied can be read from left to right rather than from inside out

User · Answer

matrix multiplication  see the following example     gt  A  lt - matrix  c 1 3 4  5 8 9  1 3 3   3 3   gt  A        1    2    3   1      1    5    1  2      3    8    3  3      4    9    3  gt    gt  B  lt - matrix  c 2 4 5  8 9 2  3 4 5   3 3   gt    gt  B        1    2    3   1      2    8    3  2      4    9    4  3      5    2    5  gt    gt    gt  A     B        1    2    3   1     27   55   28  2     53  102   56  3     59  119   63   gt  B     A        1    2    3   1     38  101   35  2     47  128   43  3     31   86   26   Also see   http   en wikipedia org wiki Matrix multiplication  If this does not follow the size of matrix rule you will get the error    gt  A  lt - matrix c 1 2 3 4 5 6   3 2       gt  A        1    2   1      1    4  2      2    5  3      3    6   gt  B  lt - matrix  c 3 1 3 4 4 4 4 4 3   3 3    gt  B            1    2    3       1      3    4    4      2      1    4    4      3      3    4    3      gt  A   B     Error in A     B   non-conformable arguments

[r] What does %>% mean in R

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