# A single treatment sequence

Source: `R/txseq.R`
`txseq.Rd`

Create a single treatment sequence for simulation modeling.

    txseq(first, second, second_plus)

## Arguments

first | The treatment to be used at first line. Must be a character of length 1.
second | A vector of length 2 where the first element is the second line treatment to be used if a patient develops a T790M mutation after first line treatment and the second element is the second line treatment to be used if the patient did not. One of the elements may be `NA` if the model begins at second line and T790M status is therefore known.
second_plus | A vector of length 2 where the first element is the post second line treatment to be used if a patient develops a T790M mutation after first line treatment and the second element is the post second line treatment to be used if the patient did not. One of the elements may be `NA` if the model begins at second line and T790M status is therefore known.

## Value

An object of class "txseq", which is a list of treatments used at first line (`first`), second line (`second`), and post second line (`second_plus`).

## See also

`txseq_list`

## Examples

    txseq <- txseq(first = "erlotinib",
                   second = c("osimertinib", "PBDC"),
                   second_plus = c("PBDC + bevacizumab", "PBDC + bevacizumab"))
    txseq$first#> [1] "erlotinib"txseq$second#>           pos           neg
    #> "osimertinib"        "PBDC" txseq$second_plus#>                  pos                  neg
    #> "PBDC + bevacizumab" "PBDC + bevacizumab"
    # T790M+ patient previously treated with erlotinib
    txseq <- txseq(first = "erlotinib",
                   second = c("osimertinib", NA),
                   second_plus = c("PBDC + bevacizumab", NA))
    txseq$first#> [1] "erlotinib"txseq$second#>           pos           neg
    #> "osimertinib"            NA txseq$second_plus#>                  pos                  neg
    #> "PBDC + bevacizumab"                   NA