Text::Table(3) User Contributed Perl Documentation Text::Table(3)NAMEText::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).
Data can contain colorizing escape sequences (as provided by
"Term::AnsiColor") without upsetting the alignment.
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()
$tb->height
returns the total number of lines in a table, including title lines
and body lines. For orthogonality, the synonym table_height() also
exists.
table_height()
Same as "$table->height()".
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.
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 greatest 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).
stringify()
Returns a string representation of the table. This method is called
for stringification by overload.
my @table_strings = map { $_->stringify() } @tables;
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);
$tb->rule( sub { my ($index, $len) = @_; },
sub { my ($index, $len) = @_; },
);
Returns a rule for the table.
A rule is a line of table width that can be used between table
lines to provide visual horizontal divisions, much like column
separators provide vertical visual divisions. In its basic form
(returned by the first call) it looks like a table line with no
data, hence a blank line except for the non-blank parts of any
column-separators. If one character is specified (the second
call), it replaces the blanks in the first form, but non-blank
column separators are retained. If a second character is
specified, it replaces the non-blank parts of the separators. So
specifying the same character twice gives a solid line of table
width. Another useful combo is "$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.
If callbacks are specified instead of the characters, then they
receive the index of the section of the rule they need to render
and its desired length in characters, and should return the string
to put there. The indexes given are 0 based (where 0 is either the
left column separator or the leftmost cell) and the strings will be
trimmed or extended in the replacement.
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 Text::Table version 1.121
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
MAINTAINER
Shlomi Fish, <http://www.shlomifish.org/> - CPAN ID: "SHLOMIF".
ORIGINAL 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 terms
of the ISC license.
(This program had been licensed under the same terms as Perl itself up
to version 1.118 released on 2011, and was relicensed by permission of
its originator).
The full text of the license can be found in the LICENSE file included
with this module.
SEE ALSO
Text::Aligner, perl(1) .
perl v5.14.1 2011-07-25 Text::Table(3)
