如何从 Perl 中的文本文件中提取/解析表格数据？

Question

我正在寻找类似 HTML::TableExtract 的东西，只是不适用于 HTML 输入，但是用于包含用缩进和间距格式化的“表格”的纯文本输入。

数据可能如下所示：

Here is some header text.

Column One       Column Two      Column Three
a                                           b
a                    b                      c


Some more text

Another Table     Another Column
abdbdbdb          aaaa

Answer 1

不知道任何打包的解决方案，但是假设您可以对文件进行两次传递，那么一些不太灵活的事情就相当简单：（以下是部分Perlish伪代码示例）

• 假设：数据可能包含空格，并且如果存在则不引用ala CSV空格 - 如果不是这种情况，只需使用 Text::CSV(_XS)。
• 假设：没有使用制表符进行格式化。
• 该逻辑将“列分隔符”定义为 100% 填充有空格的任何连续的垂直行集。
• 如果意外地每行都有一个空格，该空格是偏移量 M 个字符处的数据的一部分，则逻辑将认为偏移量 M 是列分隔符，因为它无法知道任何更好的情况。 它可以更好地了解的唯一方法是，如果您要求列分隔至少为 X 个空格，其中 X>1 - 请参阅第二个代码片段。

示例代码：

my $INFER_FROM_N_LINES = 10; # Infer columns from this # of lines
                             # 0 means from entire file
my $lines_scanned = 0;
my @non_spaces=[];
# First pass - find which character columns in the file have all spaces and which don't
my $fh = open(...) or die;
while (<$fh>) {
    last if $INFER_FROM_N_LINES && $lines_scanned++ == $INFER_FROM_N_LINES;
    chomp;
    my $line = $_;
    my @chars = split(//, $line); 
    for (my $i = 0; $i < @chars; $i++) { # Probably can be done prettier via map?
        $non_spaces[$i] = 1 if $chars[$i] ne " ";
    }
}
close $fh or die;

# Find columns, defined as consecutive "non-spaces" slices.
my @starts, @ends; # Index at which columns start and end
my $state = " "; # Not inside a column
for (my $i = 0; $i < @non_spaces; $i++) {
    next if $state eq " " && !$non_spaces[$i];
    next if $state eq "c" && $non_spaces[$i];
    if ($state eq " ") { # && $non_spaces[$i] of course => start column
        $state = "c";
        push @starts, $i;
    } else { # meaning $state eq "c" && !$non_spaces[$i] => end column
        $state = " ";
        push @ends, $i-1;
    }
}
if ($state eq "c") { # Last char is NOT a space - produce the last column end
    push @ends, $#non_spaces;
}

# Now split lines
my $fh = open(...) or die;
my @rows = ();
while (<$fh>) {
    my @columns = ();
    push @rows, \@columns;
    chomp;
    my $line = $_;
    for (my $col_num = 0; $col_num < @starts; $col_num++) {
        $columns[$col_num] = substr($_, $starts[$col_num], $ends[$col_num]-$starts[$col_num]+1);
    }
}
close $fh or die;

现在，如果您要求列分隔至少为 X 个空格，其中 X>1，它也是可行的，但列位置的解析器需要更复杂一点：

# Find columns, defined as consecutive "non-spaces" slices separated by at least 3 spaces.
my $min_col_separator_is_X_spaces = 3;
my @starts, @ends; # Index at which columns start and end
my $state = "S"; # inside a separator
NEXT_CHAR: for (my $i = 0; $i < @non_spaces; $i++) {
    if ($state eq "S") { # done with last column, inside a separator
        if ($non_spaces[$i]) { # start a new column
            $state = "c";
            push @starts, $i;
        }
        next;
    }
    if ($state eq "c") { # Processing a column
        if (!$non_spaces[$i]) { # First space after non-space
                                # Could be beginning of separator? check next X chars!
            for (my $j = $i+1; $j < @non_spaces
                            || $j < $i+$min_col_separator_is_X_spaces; $j++) {
                 if ($non_spaces[$j]) {
                     $i = $j++; # No need to re-scan again
                     next NEXT_CHAR; # OUTER loop
                 }
                 # If we reach here, next X chars are spaces! Column ended!
                 push @ends, $i-1;
                 $state = "S";
                 $i = $i + $min_col_separator_is_X_spaces;
            }
         }
        next;
    }
}

Answer 2

这是一个非常快速的解决方案，并带有概述。 （我对长度表示歉意。）基本上，如果一个“单词”出现在列标题 n 开始之后，那么它最终会出现在 n 列中，除非它的大部分内容都在 n 列中。 body 进入列 n + 1，在这种情况下，它会在那里结束。整理它、扩展它以支持多个不同的表等都作为练习。您还可以使用列标题左偏移以外的其他内容作为边界标记，例如中心或由列号确定的某个值。

#!/usr/bin/perl


use warnings;
use strict;


# Just plug your headers in here...
my @headers = ('Column One', 'Column Two', 'Column Three');

# ...and get your results as an array of arrays of strings.
my @result = ();


my $all_headers = '(' . (join ').*(', @headers) . ')';
my $found = 0;
my @header_positions;
my $line = '';
my $row = 0;
push @result, [] for (1 .. @headers);


# Get lines from file until a line matching the headers is found.

while (defined($line = <DATA>)) {

    # Get the positions of each header within that line.

    if ($line =~ /$all_headers/) {
        @header_positions = @-[1 .. @headers];
        $found = 1;
        last;
    }

}


$found or die "Table not found! :<\n";


# For each subsequent nonblank line:

while (defined($line = <DATA>)) {
    last if $line =~ /^$/;

    push @{$_}, "" for (@result);
    ++$row;

    # For each word in line:

    while ($line =~ /(\S+)/g) {

        my $word = $1;
        my $position = $-[1];
        my $length = $+[1] - $position;
        my $column = -1;

        # Get column in which word starts.

        while ($column < $#headers &&
            $position >= $header_positions[$column + 1]) {
            ++$column;
        }

        # If word is not fully within that column,
        # and more of it is in the next one, put it in the next one.

        if (!($column == $#headers ||
            $position + $length < $header_positions[$column + 1]) &&
            $header_positions[$column + 1] - $position <
            $position + $length - $header_positions[$column + 1]) {

            my $element = \$result[$column + 1]->[$row];
            $element .= " $word";

        # Otherwise, put it in the one it started in.

        } else {

            my $element = \$result[$column]->[$row];
            $element .= " $word";

        }

    }

}


# Output! Eight-column tabs work best for this demonstration. :P

foreach my $i (0 .. $#headers) {
    print $headers[$i] . ": ";
    foreach my $c (@{$result[$i]}) {
        print "$c\t";
    }
    print "\n";
}


__DATA__

This line ought to be ignored.

Column One       Column Two      Column Three
These lines are part of the tabular data to be processed.
The data are split based on how much words overlap columns.

This line ought to be ignored also.

示例输出：

Column One:      These lines are         The data are split
Column Two:      part of the tabular     based on how
Column Three:    data to be processed.   much words overlap columns.