These helpers take two endpoints and return the sequence of all
integers within that interval. For `seq2_along()`

, the upper
endpoint is taken from the length of a vector. Unlike
`base::seq()`

, they return an empty vector if the starting point is
a larger integer than the end point.

seq2(from, to) seq2_along(from, x)

from | The starting point of the sequence. |
---|---|

to | The end point. |

x | A vector whose length is the end point. |

An integer vector containing a strictly increasing sequence.

seq2(2, 10)#> [1] 2 3 4 5 6 7 8 9 10seq2(10, 2)#> integer(0)#> [1] 10 9 8 7 6 5 4 3 2seq2_along(10, letters)#> [1] 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26