$re = '/^library\((.*)\)/m';
$str = 'library(ggplot2)
library(ggplot2, stringr)
library("ggplot2")
library("ggplot2", "yarrr")
# library(neotoma)
require(stringr)
#\' @import fields
#\' @importFrom neotoma compile_taxa
neotoma::get_dataset()';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php