read_multi_fwf: Read Fixed Width Format Files containing lines of different...

In prontog/multifwf: Read Fixed Width Format Files Containing Lines of Different Type

Description

Read a table of fixed width formatted data of different types into a tibble for each type.

Usage

read_multi_fwf(file, multi.specs, select, skip = 0, n = -1, ...)

Arguments

file	either a path to a file, a connection, or literal data (either a single string or a raw vector). Files ending in .gz, .bz2, .xz, or .zip will be automatically uncompressed. Files starting with http://, https://, ftp://, or ftps:// will be automatically downloaded. Remote gz files can also be automatically downloaded and decompressed. Literal data is most useful for examples and tests. It must contain at least one new line to be recognised as data (instead of a path) or be a vector of greater than length 1. Using a value of clipboard() will read from the system clipboard.
multi.specs	A named list of data.frames containing the following columns: widths see fwf_widths col_names see fwf_widths For more info on these fields see read_fwf. Note that each list item should have a name. This is important for the select function.
select	A function to select the type of a line. This selector should have parameters: line the line specs the multi.specs list that was passed to read.multi.fwf The select function should return the name of the spec that matches the line. read.multi.fwf will then use this name to select the a spec from the passed multi.spec. This is why multi.spec should be a named list. If there is no match then NULL can be returned.
skip	number of initial lines to skip; see read_fwf.
n	the maximum number of records (lines) to be read, defaulting to no limit.
...	further arguments to be passed to read_fwf.

Value

Return value is a named list with an item for each spec in multi.spec. If there was at least one line in file, matching a spec, then the named item will be a tibble. Otherwise it will be NULL.

Author(s)

Panos Rontogiannis [e-mail]

See Also

read_fwf

Examples

ff <- tempfile()
cat(file = ff, '123456', '287654', '198765', sep = '\n')
specs <- list()
specs[['sp1']] = data.frame(widths = c(1, 2, 3), 
                            col_names = c('Col1', 'Col2', 'Col3'))
specs[['sp2']] = data.frame(widths = c(3, 2, 1), 
                            col_names = c('C1', 'C2', 'C3'))

myselector <- function(line, specs) {
    s <- substr(line, 1, 1)
    spec_name = ''
    if (s == '1')
        spec_name = 'sp1'
    else if (s == '2')
        spec_name = 'sp2'

    spec_name
}

read_multi_fwf(ff, multi.specs = specs, select = myselector)    
#> sp1: 1 23 456 \ 1 98 765, sp2: 287 65 4

unlink(ff)

prontog/multifwf documentation built on May 26, 2019, 8:34 a.m.