Dave Mason continues his look at matrices in R:

We can extract an entire row from a matrix. To do this, specify the desired row only within the square brackets [ ]. The placeholder where you would otherwise specify the column is left empty.

> #Points scored by Kendrick Perkins. > points_scored_by_quarter[1,] 1st 2nd 3rd 4th 2 2 6 0 > points_scored_by_quarter["Perkins",] 1st 2nd 3rd 4th 2 2 6 0Conversely, we can extract a column from a matrix. Specify the column within the square brackets [ ]and omit the row. The result is a vector, thus the pivot effect–the row names are displayed in the output (not the column name).

Dave points out that working with matrices is basically an extension of working with vectors.

Kevin Feasel

2018-08-20

R