复制和修改文件以合并其他数据

Question

我是Perl的新手，我仍然处于探索/初学者阶段。

我有一个文本文件，如下所示：

Naam;ISIN;Symbol;Market;Trading Currency\n
IDI;FR0000051393;IDIP;Euronext Paris;EUR\n
BETER BED;NL0000339703;BBED;Euronext Amsterdam;EUR\n
ALCATEL-LUCENT;FR0000130007;ALU;Euronext Paris;EUR\n
FIPP;FR0000038184;FIPP;Euronext Paris;EUR\n
...

使用下面的代码，我可以读取散列/列表中的文本文件。

use strict;
use warnings;

my %data;
my @names;

my $myFile = "myfile.csv";
open(FH, '<', $myFile) or error("Cannot open file ($!)");

while (<FH>) {
    chomp;
    my @list = split(';');
    for (my $i = 0; $i <= $#list; $i++) {
        if ($. == 1) {
            $names[$i] = $list[$i];
        } else {
            push @{$data{$names[$i]}}, $list[$i];
        }
    }
}
close FH;

我有以下两个问题。

1. 我希望创建一个名为Ticker的额外列(散列/列表)，它大致执行以下操作： if ($Market eq "Euronext Paris") { $Symbol = "$Symbol.PA"；{print "$Symbol\n"}；} elsif ($Market eq "Euronext布鲁塞尔“){ $Symbol = "$Symbol.BR"；{print "$Symbol\n"}； 其他市场也是如此。(注意，当我将文件读取到数组中时，上面的代码工作正常，但我发现很难修改与哈希/列表兼容的语法。)
2. 如何将列:名称、符号、市场和Ticker导出到由标签分隔的文本文件中？

Answer 1

由于您正在对输入文件进行相当简单的转换，最好是读取输入文件并同时创建输出文件。我已经对您的脚本进行了修改，并在整个代码中对所发生的事情进行了注释。如果你不明白剧本在做什么，请问一问。

#!/usr/bin/perl
use warnings;
use strict;

# here are some tickers (including some I made up)
# initialise these at the top of your script in a hash
# if you want to get the abbreviation for, say, 'Euronext Roma',
# you access it using $tickers{'Euronext Roma'}
my %tickers = (
    'Euronext Paris' => 'PA',
    'Euronext Brussels' => 'BR',
    'Euronext Madrid' => 'MA',
    'Euronext Roma' => 'RO'
);

# set up the input file
my $infile = "myfile.csv";
open my $in, '<', $infile or die "Cannot open file $infile: $!";

# this will be our output
my $outfile = 'stocks_with_tickers.txt';
open my $out, '>', $outfile or die "Cannot open file $outfile: $!";

# print out the column headers for the new file
# the function join takes a separator as its first argument,
# and joins the array of variables following it with that separator
print { $out } join "\t", "Name", "Symbol", "Market", "Ticker\n";

# input file format:
# Naam;ISIN;Symbol;Market;Trading Currency
# when we split the line to form an array, we will want the values
# in array positions 0, 2, 3 (the first array position is 0 in Perl)

# output file format:
# Name; Symbol; Market; Ticker
# we get the ticker by looking for $tickers{ MARKET }
#

while (<$in>){
    # skip the line unless it contains some alphanumeric characters
    next unless /\w+/;
    # $. is the number of the line that we are on.
    # Skip the first line of the file (the header row)
    if ($. == 1) {
        next;
    }

    # split up the line
    my @list = split ";";
    # print cols 0, 2, 3 to the output
    # note that the braces around $out ( i.e. { $out } ) are to make it
    # clearer that $out is the file that you're printing the results in
    print { $out } join "\t", $list[0], $list[2], $list[3],

    # we're going to use the ternary form of if/else, which allows
    # us to do an in/else test within the print statement
    # this line tests if $tickers{ MARKET } exists
    ( exists $tickers{ $list[3] } )
    # if it does, print out the market symbol plus the ticker abbrev
    ? $list[2] . "." . $tickers{$list[3]} . "\n"
    # otherwise, leave it blank
    : "\n";
}
close $in;
close $out;
# we're done!