如何快速求和文件中的所有数字? [英] How can I quickly sum all numbers in a file?

问题描述

我有一个包含数千个数字的文件，每个数字都在自己的一行中:

I have a file which contains several thousand numbers, each on it's own line:

34
42
11
6
2
99
...

我想写一个脚本来打印文件中所有数字的总和.我有一个解决方案，但效率不高.(运行需要几分钟.)我正在寻找更有效的解决方案.有什么建议吗?

I'm looking to write a script which will print the sum of all numbers in the file. I've got a solution, but it's not very efficient. (It takes several minutes to run.) I'm looking for a more efficient solution. Any suggestions?

推荐答案

对于 Perl one-liner，它与 Ayman Hourieh 的回答:

For a Perl one-liner, it's basically the same thing as the awk solution in Ayman Hourieh's answer:

 % perl -nle '$sum += $_ } END { print $sum'

如果您对 Perl one-liners 的作用感到好奇，您可以解析它们:

If you're curious what Perl one-liners do, you can deparse them:

 %  perl -MO=Deparse -nle '$sum += $_ } END { print $sum'

结果是程序的一个更冗长的版本，以一种没人会自己编写的形式:

The result is a more verbose version of the program, in a form that no one would ever write on their own:

BEGIN { $/ = "
"; $ = "
"; }
LINE: while (defined($_ = <ARGV>)) {
    chomp $_;
    $sum += $_;
}
sub END {
    print $sum;
}
-e syntax OK

只是为了傻笑，我用一个包含 1,000,000 个数字(在 0 - 9,999 范围内)的文件进行了尝试.在我的 Mac Pro 上，它几乎立即恢复.这太糟糕了，因为我希望使用 mmap 会非常快，但它只是在同一时间:

Just for giggles, I tried this with a file containing 1,000,000 numbers (in the range 0 - 9,999). On my Mac Pro, it returns virtually instantaneously. That's too bad, because I was hoping using mmap would be really fast, but it's just the same time:

use 5.010;
use File::Map qw(map_file);

map_file my $map, $ARGV[0];

$sum += $1 while $map =~ m/(d+)/g;

say $sum;

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