From the Text::Table documentation:
NAME
Text::Table - Organize Data in Tables
SYNOPSIS
use Text::Table;
my $tb = Text::Table->new(
"Planet", "Radius\nkm", "Density\ng/cm^3"
);
$tb->load(
[ "Mercury", 2360, 3.7 ],
[ "Venus", 6110, 5.1 ],
[ "Earth", 6378, 5.52 ],
[ "Jupiter", 71030, 1.3 ],
);
print $tb;
This prints a table from the given title and data like this:
Planet Radius Density
km g/cm^3
Mercury 2360 3.7
Venus 6110 5.1
Earth 6378 5.52
Jupiter 71030 1.3
Note that two-line titles work, and that the planet names are aligned
differently than the numbers.
DESCRIPTION
Organization of data in table form is a time-honored and useful method
of data representation. While columns of data are trivially generated by
computer through formatted output, even simple tasks like keeping titles
aligned with the data columns are not trivial, and the one-shot
solutions one comes up with tend to be particularly hard to maintain.
Text::Table allows you to create and maintain tables that adapt to
alignment requirements as you use them.
Overview
The process is simple: you create a table (a Text::Table object) by
describing the columns the table is going to have. Then you load lines
of data into the table, and finally print the resulting output lines.
Alignment of data and column titles is handled dynamically in dependence
on the data present.
Table Creation
In the simplest case, if all you want is a number of (untitled) columns,
you create an unspecified table and start adding data to it. The number
of columns is taken fronm the first line of data.
To specify a table you specify its columns. A column description can
contain a title and alignment requirements for the data, both optional.
Additionally, you can specify how the title is aligned with the body of
a column, and how the lines of a multiline title are aligned among
themselves.
The columns are collected in the table in the order they are given. On
data entry, each column corresponds to one data item, and in column
selection columns are indexed left to right, starting from 0.
Each title can be a multiline string which will be blank-filled to the
length of the longest partial line. The largest number of title lines in
a column determines how many title lines the table has as a whole,
including the case that no column has any titles.
On output, Columns are separated by a single blank. You can control what
goes between columns by specifying separators between (or before, or
after) columns. Separators don't contain any data and don't count in
column indexing. They also don't accumulate: in a sequence of only
separators and no columns, only the last one counts.
Status Information
The width (in characters), height (in lines), number of columns, and
similar data about the table is available.
Data Loading
Table data is entered line-wise, each time specifying data entries for
all table columns. A bulk loader for many lines at once is also
available. You can clear the data from the table for re-use (though you
will more likely just create another table).
Table Output
The output area of a table is divided in the title and the body.
The title contains the combined titles from the table columns, if any.
Its content never changes with a given table, but it may be spread out
differently on the page through alignment with the data.
The body contains the data lines, aligned column-wise as specified, and
left-aligned with the column title.
Each of these is arranged like a Perl array (counting from 0) and can be
accessed in portions by specifying a first line and the number of
following lines. Also like an array, giving a negative first line counts
from the end of the area. The whole table, the title followed by the
body, can also be accessed in this manner.
The subdivisions are there so you can repeat the title (or parts of it)
along with parts of the body on output, whether for screen paging or
printout.
A rule line is also available, which is the horizontal counterpart to
the separator columns you specify with the table. It is basically a
table line as it would appear if all data entries in the line were
empty, that is, a blank line except for where the column separators have
non-blank entries. If you print it between data lines, it will not
disrupt the vertical separator structure as a plain blank line would.
You can also request a solid rule consisting of any character, and even
one with the non-blank column separators replaced by a character of your
choice. This way you can get the popular representation of
line-crossings like so:
|
----+---
|
Warning Control
On table creation, some parameters are checked and warnings issued if
you allow warnings. You can also turn warnings into fatal errors.
SPECIFICATIONS
Column Specification
Each column specification is a single scalar. Columns can be either
proper data columns or column separators. Both can be specified either
as (possibly multi-line) strings, or in a more explicit form as
hash-refs. In the string form, proper columns are given as plain
strings, and separators are given as scalar references to strings. In
hash form, separators have a true value in the field "is_sep" while
proper columns don't have this field.
Columns as strings
A column is given as a column title (any number of lines),
optionally followed by alignment requirements. Alignment
requirements start with a line that begins with an ampersamd "&".
However, only the last such line counts as such, so if you have
title lines that begin with "&", just append an ampersand on a line
by itself as a dummy alignment section if you don't have one anyway.
What follows the ampersand on its line is the alignment style (like
*left*, *right*, ... as described in "Alignment"), you want for the
data in this column. If nothing follows, the general default *auto*
is used. If you specify an invalid alignment style, it falls back to
left alignment.
The lines that follow can contain sample data for this column. These
are considered for alignment in the column, but never actually
appear in the output. The effect is to guarantee a minimum width for
the column even if the current data doesn't require it. This helps
dampen the oscillations in the appearance of dynamically aligned
tables.
Columns as Hashes
The format is
{
title => $title,
align => $align,
sample => $sample,
align_title => $align_title,
align_title_lines => $align_title_lines,
}
$title contains the title lines and $sample the sample data. Both
can be given as a string or as an array-ref to the list of lines.
$align contains the alignment style (without a leading ampersand),
usually as a string. You can also give a regular expression here,
which specifies regex alignment. A regex can only be specified in
the hash form of a colunm specification.
In hash form you can also specify how the title of a column is
aligned with its body. To do this, you specify the keyword
"align_title" with "left", "right" or "center". Other alignment
specifications are not valid here. The default is "left".
"align_title" also specifies how the lines of a multiline title are
aligned among themselves. If you want a different alignment, you can
specify it with the key "align_title_lines". Again, only "left",
"right" or "center" are allowed.
Do not put other keys than those mentioned above (*title*, *align*,
*align_title*, *align_title_lines*, and *sample*) into a hash that
specifies a column. Most would be ignored, but some would confuse
the interpreter (in particular, *is_sep* has to be avoided).
Separators as strings
A separator must be given as a reference to a string (often a
literal, like "\' | '"), any string that is given directly describes
a column.
It is usually just a (short) string that will be printed between
table columns on all table lines instead of the default single
blank. If you specify two separators (on two lines), the first one
will be used in the title and the other in the body of the table.
Separators as Hashes
The hash representation of a separator has the format
{
is_sep => 1,
title => $title,
body => $body,
}
$title is the separator to be used in the title area and $body the
one for the body. If only one is given, the other is used for both.
If none is given, a blank is used. If one is shorter than the other,
it is blank filled on the right.
The value of "is_sep" must be set to a true value, this is the
distinguishing feature of a separator.
Alignment
The original documentation to Text::Aligner contains all the details on
alignment specification, but here is the rundown:
The possible alignment specifications are *left*, *right*, *center*,
*num* and *point* (which are synonyms), and *auto*. The first three
explain themselves.
*num* (and *point*) align the decimal point in the data, which is
assumed to the right if none is present. Strings that aren't numbers are
treated the same way, that is, they appear aligned with the integers
unless they contain a ".". Instead of the decimal point ".", you can
also specify any other string in the form *num(,)*, for instance. The
string in parentheses is aligned in the data. The synonym *point* for
*num* may be more appropriate in contexts that deal with arbitrary
strings, as in *point(=>)* (which might be used to align certain bits of
Perl code).
*regex alignment* is a more sophisticated form of point alignment. If
you specify a regular expression, as delivered by "qr//", the start of
the match is used as the alignment point. If the regex contains
capturing parentheses, the last submatch counts. [The usefulness of this
feature is under consideration.]
*auto* alignment combines numeric alignment with left alignment. Data
items that look like numbers, and those that don't, form two virtual
columns and are aligned accordingly: "num" for numbers and "left" for
other strings. These columns are left-aligned with each other (i.e. the
narrower one is blank-filled) to form the final alignment.
This way, a column that happens to have only numbers in the data gets
*num* alignment, a column with no numbers appears *left*-aligned, and
mixed data is presented in a reasonable way.
Column Selection
Besides creating tables from scratch, they can be created by selecting
columns from an existing table. Tables created this way contain the data
from the columns they were built from.
This is done by specifying the columns to select by their index (where
negative indices count backward from the last column). The same column
can be selected more than once and the sequence of columns can be
arbitrarily changed. Separators don't travel with columns, but can be
specified between the columns at selection time.
You can make the selection of one or more columns dependent on the data
content of one of them. If you specify some of the columns in angle
brackets [...], the whole group is only included in the selection if the
first column in the group contains any data that evaluates to boolean
true. That way you can de-select parts of a table if it contains no
interesting data. Any column separators given in brackets are selected
or deselected along with the rest of it.
PUBLIC METHODS
Table Creation
new()
my $tb = Text::Table->new( $column, ... );
creates a table with the columns specified. A column can be proper
column which contains and displays data, or a separator which tells
how to fill the space between columns. The format of the parameters
is described under "Column Specification". Specifying an invalid
alignment for a column results in a warning if these are allowed.
If no columns are specified, the number of columns is taken from the
first line of data added to the table. The effect is as if you had
specified "Text::Table->new( ( '') x $n)", where $n is the number of
columns.
select()
my $sub = $tb->select( $column, ...);
creates a table from the listed columns of the table $tb, including
the data. Columns are specified as integer indices which refer to
the data columns of $tb. Columns can be repeated and specified in
any order. Negative indices count from the last column. If an
invalid index is specified, a warning is issued, if allowed.
As with "new()", separators can be interspersed among the column
indices and will be used between the columns of the new table.
If you enclose some of the arguments (column indices or separators)
in angle brackets "[...]" (technically, you specify them inside an
arrayref), they form a group for conditional selection. The group is
only included in the resulting table if the first actual column
inside the group contains any data that evaluate to a boolean true.
This way you can exclude groups of columns that wouldn't contribute
anything interesting. Note that separators are selected and
de-selected with their group. That way, more than one separator can
appear between adjacent columns. They don't add up, but only the
rightmost separator is used. A group that contains only separators
is never selected. [Another feature whose usefulness is under
consideration.]
Status Information
n_cols()
$tb->n_cols
returns the number of columns in the table.
width()
$tb->width
returns the width (in characters) of the table. All table lines have
this length (not counting a final "\n" in the line), as well as the
separator lines returned by $tb->rule() and $b->body_rule(). The
width of a table can potentially be influenced by any data item in
it.
height()
$tb->height
returns the total number of lines in a table, including title lines
and body lines. For orthogonality, the synonym table_height() also
exists.
title_height()
$tb->title_height
returns the number of title lines in a table.
body_height()
$tb->body_height
returns the number of lines in the table body, which is the number
of data lines that were entered via "add()" or "load()".
colrange()
$tb->colrange( $i)
returns the start position and width of the $i-th column (counting
from 0) of the table. If $i is negative, counts from the end of the
table. If $i is larger than the greatesit column index, an imaginary
column of width 0 is assumed right of the table.
Data Loading
add()
$tb->add( $col1, ..., $colN)
adds a data line to the table, returns the table.
$col1, ..., $colN are scalars that correspond to the table columns.
Undefined entries are converted to '', and extra data beyond the
number of table columns is ignored.
Data entries can be multi-line strings. The partial strings all go
into the same column. The corresponding fields of other columns
remain empty unless there is another multi-line entry in that column
that fills the fieds. Adding a line with multi-line entries is
equivalent to adding multiple lines.
Every call to "add()" increases the body height of the table by the
number of effective lines, one in the absence of multiline entries.
load()
$tb->load( $line, ...)
loads the data lines given into the table, returns the table.
Every argument to "load()" represents a data line to be added to the
table. The line can be given as an array(ref) containing the data
items, or as a string, which is split on whitespace to retrieve the
data. If an undefined argument is given, it is treated as an empty
line.
clear()
$tb->clear;
deletes all data from the table and resets it to the state after
creation. Returns the table. The body height of a table is 0 after
"clear()".
Table Output
The three methods "table()", "title()", and "body()" are very similar.
They access different parts of the printable output lines of a table
with similar methods. The details are described with the "table()"
method.
table()
The "table()" method returns lines from the entire table, starting
with the first title line and ending with the last body line.
In array context, the lines are returned separately, in scalar
context they are joined together in a single string.
my @lines = $tb->table;
my $line = $tb->table( $line_number);
my @lines = $tb->table( $line_number, $n);
The first call returns all the lines in the table. The second call
returns one line given by $line_number. The third call returns $n
lines, starting with $line_number. If $line_number is negative, it
counts from the end of the array. Unlike the "select()" method,
"table()" (and its sister methods "title()" and "body()") is
protected against large negative line numbers, it truncates the
range described by $line_number and $n to the existing lines. If $n
is 0 or negative, no lines are returned (an empty string in scalar
context).
title()
Returns lines from the title area of a table, where the column
titles are rendered. Parameters and response to context are as with
"table()", but no lines are returned from outside the title area.
body()
Returns lines from the body area of a table, that is the part where
the data content is rendered, so that $tb->body( 0) is the first
data line. Parameters and response to context are as with "table()".
rule()
$tb->rule;
$tb->rule( $char);
$tb->rule( $char, $char1);
Returns a rule for the table.
A rule is a line of table width that can be used between table lines
to provide visual horizontal divisions, much like column separators
provide vertical visual divisions. In its basic form (returned by
the first call) it looks like a table line with no data, hence a
blank line except for the non-blank parts of any column-separators.
If one character is specified (the second call), it replaces the
blanks in the first form, but non-blank column separators are
retained. If a second character is specified, it replaces the
non-blank parts of the separators. So specifying the same character
twice gives a solid line of table width. Another useful combo is
"$tb-<rule( '-', '+')", together with separators that contain a
single nonblank "|", for a popular representation of line crossings.
"rule()" uses the column separators for the title section if there
is a difference.
body_rule()
"body_rule()" works like <rule()>, except the rule is generated
using the column separators for the table body.
Warning Control
warnings()
Text::Table->warnings();
Text::Table->warnings( 'on');
Text::Table->warnings( 'off'):
Text::Table->warnings( 'fatal'):
The "warnings()" method is used to control the appearance of warning
messages while tables are manipulated. When Text::Table starts,
warnings are disabled. The default action of "warnings()" is to turn
warnings on. The other possible arguments are self-explanatory.
"warnings()" can also be called as an object method ("$tb->warnings(
...)").
VERSION
This document pertains to $Revision: 1.105 $
BUGS
o *auto* alignment doesn't support alternative characters for the
decimal point. This is actually a bug in the underlying
Text::Aligner by the same author.
AUTHOR
Anno Siegel
CPAN ID: ANNO
siegel@zrz.tu-berlin.de
http://www.tu-berlin.de/~siegel
COPYRIGHT
Copyright (c) 2002 Anno Siegel. All rights reserved. This program is
free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.
SEE ALSO
Text::Aligner, perl(1).