sed_insert: Insert one or more lines
In pnnl/rsed: Stream Editing

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/sed_insert.R

Insert one or more lines

1	sed_insert(stream, after, insertion, warn = FALSE, ...)

`stream`	A character vector, each element typically (but not necessarily) containing the text from a single line in a file, which can be generated via `readLines`.
`after`	An integer or character string that designates where `insertion` is added to `stream`. If `after` is numeric, it designates the line (or element) number in `stream` after which the `insertion` will be placed. The numeric value of `after` must be in `[0:length(stream)]`. To make an insertion at the very beginning of `stream`, use `after = 0`. If `after` is a character string, the insertion is placed after the first element in `stream` that contains the string, where matching is obtained using `grep`.
`insertion`	A character vector that will be inserted into the stream after element `after`. Each element in the vector would correspond to a separate line in the file.
`warn`	If `TRUE`, warning messages are produced if insertion fails due to mispecifification of `after`.
`...`	Additional named arguments to `grep`, which are applicable if `after` is a character string. In other words, `grep` is used to search for the first instance of `after`.

sed_insert only accomodates a single insertion point. Multiple lines may be inserted, but only one insertion point is allowed, which is why length(insertion) must be 1. To make insertions at multiple locations, sed_insert can be called repeatedly on the same string as needed.

The new stream with the insertions added. If the insertion fails because after is specified incorrectly, stream is returned unchanged.

Landon Sego

sed_replace, sed_substitute, sed_comment, streamEdit

################################################################################
# Let's create an example stream we can edit
################################################################################
stream <- c("Here's a line",
           "And another line",
           "Line after which we'll insert a string",
           "A line after which we'll insert another string",
           "A final line")
as.stream(stream)

# Insert a string using line numbers
stream <- sed_insert(stream, after = 3, "Here's the first insertion")
stream

# Insert a stream by searching for a string
stream <- sed_insert(stream,
                    c("Here's the second insertion",
                      "",
                      "Another line of the second insertion after the blank line"),
                    after = "insert another")
stream