# NAME

Math::Histogram::Axis - Object representing single histogram dimension

# SYNOPSIS

```
use Math::Histogram;
# 10 bins between 0 and 1
my $fixed_bin = Math::Histogram::Axis->new(10, 0., 1.);
# 5 bins of variable size
my $var_bin = Math::Histogram::Axis->new([1, 2, 4, 8, 16]);
```

# DESCRIPTION

An object of this class represents the binning information along one dimension of an N-dimensional histogram. A 1-D histogram will require one axis, a 2-D histogram two axises, etc. Axises can contain a number of equal-sized bins (also referred to as fixed-bin axises in other parts of the documentation) or a number of explicitly specified variable-width bins. Some of the algorithms, most notably the one for determining the bin number for a given coordinate, will be O(1) for fixed-width binning, but O(log(n)) for variable-width binning.

# METHODS

## new

The constructor takes one or three arguments. With three arguments, the axis will have fixed-width bins. The first argument is the number of bins on the axis, the second is the lower boundary of the first bin, the third is the upper boundary of the last bin.

One argument indicates a variable-width binning. The argument must be a reference to an array of floating point numbers that increase strictly monotonically. They are interpreted in order as the lower boundary of the first bin, the boundary between first and second bin, ... and finally the upper boundary of the last bin. Given N elements of the array reference, the axis will have N-1 bins.

Bin numbers start at 1 since the bin with number 0 is the underflow bin which technically has the range (-Infty., min), so excluding the lower limit of the first bin.

## clone

Returns a deep clone of the axis object.

## nbins

Returns the number of bins on the axis.

## min

Returns the lower boundary of the first bin of the axis.

## max

Returns the upper boundary of the last bin of the axis.

## width

Returns the total width of all bins combined. Yes, that's simply `$axis->max - $axis->min`

.

## binsize

Given a bin number, returns the width of that bin. Defaults to '1', so for axis objects with fixed-width binning, calling this method without argument is valid.

## lower_boundary

Given a bin number, returns the lower boundary of that bin.

## upper_boundary

Given a bin number, returns the upper boundary of that bin.

## bin_center

Given a bin number, returns the center of that bin.

## find_bin

Given a coordinate, finds the bin number of the bin it lies in. Returns 0 for underflow and `$nbins + 1`

for overflow.

## serialize

Returns a JSON string that represents this axis object.

## deserialize

Class method. Given a JSON string as generated by `serialize()`

, recreates the axis object that it represents. Also accepts a scalar reference to a JSON string.

# SEE ALSO

# AUTHOR

Steffen Mueller, <smueller@cpan.org>

# COPYRIGHT AND LICENSE

Copyright (C) 2012 by Steffen Mueller

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.1 or, at your option, any later version of Perl 5 you may have available.