如何在roxygen literate programming中逃避％？

Question

我的函數的參數的默認值包含「％」。這似乎是roxygen的一個問題，它會產生很多警告，而在嘗試構建latex文檔時，R CMD檢查會失敗。

如何使此功能（及其文檔）工作？使用%%或\％代替％不會有幫助。

#' Test escape \% from in-source documentation (roxygen). 
#' 
#' What happens when parameters contain special latex characters? 
#' 
#' @param x unsuspicious parameter 
#' @param format sprintf format string (default "\%5.0f") 
#' 
#' @return formatted string 
#' @export 
#' @author Karsten Weinert 
testroxy <- function(x, format = "%5.0f") { 
    sprintf(format,x) 
} 

Answer 1

#!/usr/bin/perl 
use strict; 
use File::Temp qw/tempfile/; 
use File::Copy; 

my $usage = <<EOD 

    $0 file1.Rd [file2.Rd ...] 

    When using roxygen to generate documentation for an R pacakge, if a default 
    argument has a percent sign in it then roxygen will copy it directly into 
    the .Rd file. Since .Rd is basically latex, this will be interpreted as a 
    comment and case the file to be parsed incorrectly. 

    For percent signs elsewhere in your documentation, for example in the 
    description of one of the parameters, you should use "\%" so parse_Rd 
    interprets it correctly. 

    But you cannot do this in the default arguments because they have to be 
    valid R code, too. 

    Since the .Rd files are automatically generated they should not have 
    any latex comments in them anyway. 

    This script escapes every unescaped % within the file. 

    The .Rd files are modified in place, since it would be easy to 
    generate them again with R CMD roxygen. 

EOD 
; 

my $n_tot = 0; 
my $n_file = @ARGV; 
my $n_esc_file = 0; 
foreach my $fn (@ARGV) { 

    print STDERR ' ' x 100, "\rWorking on $fn\t"; 
    open my $fh, $fn or die "Couldn't open $fn: $!"; 
    my ($tmp_fh, $tmp_fn) = tempfile(); 

    my $n; 
    while(<$fh>) { 
    $n += s/(?<!\\)%/\\%/g; # if % is not preceded with backslash then replace it with '\%' 
    print $tmp_fh $_; 
    } 
    $n_tot += $n; 
    $n_esc_file ++ if $n; 
    print "Escaped $n '%'\n" if $n; 
    close $tmp_fh; 
    move($tmp_fn => $fn); 
} 

print "\n"; 

print "$n_file files parsed\n"; 
print "$n_esc_file contained at least one unescaped %\n"; 
print "$n_tot total % were escaped\n"; 

這是我的不雅的解決方案。保存perl腳本，例如，escape_percents.pl，則順序是這樣的：

R CMD roxygen my.package 
perl escape_percents.pl my.package.roxygen/man/*.Rd 
R CMD install my.package.roxygen 

這可能會引入更多的問題，例如，如果您使用%%作爲模運算符有示例代碼，但它對我來說很方便。

Answer 2

代碼類似於問題中的代碼對我來說沒有問題，並生成正確的文檔。正如多個評論所說，原因必須是我正在使用roxygen2軟件包。所以，只用反斜槓使用roxygen2然後逃離「％」的文件中：

#' The percentage sign is written in the documentation like this: \%.