# MDArray

MDArray is a multi dimensional array implemented for JRuby inspired by

NumPy (www.numpy.org)

and Narray (narray.rubyforge.org) by Masahiro Tanaka. MDArray stands on

the shoulders of

Java-NetCDF and Parallel Colt.

NetCDF-Java Library is a Java interface to NetCDF files, as well as to

many

other types of

scientific data formats. It is developed and distributed by Unidata (

http://www.unidata.ucar.edu).

Parallel Colt

(sites.google.com/site/piotrwendykier/software/parallelcolt)

is a multithreaded

version of Colt (redirect...). Colt provides a

set

of Open Source

Libraries for High Performance Scientific and Technical Computing in

Java.

Scientific

and technical computing is characterized by demanding problem sizes and

a

need for high

performance at reasonably small memory footprint.

# MDArray and SciRuby

MDArray subscribes fully to the SciRuby Manifesto (http://sciruby.com/).

"Ruby has for some time had no equivalent to the beautifully constructed

NumPy, SciPy,

and matplotlib libraries for Python.

We believe that the time for a Ruby science and visualization package

has

come. Sometimes

when a solution of sugar and water becomes super-saturated, from it

precipitates a pure,

delicious, and diabetes-inducing crystal of sweetness, induced by no

more

than the tap

of a finger. So is occurring now, we believe, with numeric and

visualization libraries for Ruby."

# Main properties

- Homogeneous multidimensional array, a table of elements (usually

numbers), all of the

same type, indexed by a tuple of positive integers; - Easy calculation for large numerical multi dimensional arrays;
- Basic types are: boolean, byte, short, int, long, float, double,

string, structure; - Based on JRuby, which allows importing Java libraries;
- Operator: +,-,*,/,%,**, >, >=, etc.
- Functions: abs, ceil, floor, truncate, is_zero, square, cube,

fourth; - Binary Operators: &, |, ^, ~ (binary_ones_complement), <<, >>;
- Ruby Math functions: acos, acosh, asin, asinh, atan, atan2, atanh,

cbrt, cos, erf, exp,

gamma, hypot, ldexp, log, log10, log2, sin, sinh, sqrt, tan, tanh,

neg; - Boolean operations on boolean arrays: and, or, not;
- Fast descriptive statistics from Parallel Colt (complete list found

bellow); - Easy manipulation of arrays: reshape, reduce dimension, permute,

section, slice, etc. - Reading of two dimensional arrays from CSV files (mainly for

debugging

and simple

testing purposes); - StatList: a list that can grow/shrink and that can compute Parallel

Colt descriptive

statistics.

# Descriptive statistics methods

auto_correlation, correlation, covariance, durbin_watson, frequencies,

geometric_mean,

harmonic_mean, kurtosis, lag1, max, mean, mean_deviation, median, min,

moment, moment3,

moment4, pooled_mean, pooled_variance, product, quantile,

quantile_inverse,

rank_interpolated, rms, sample_covariance, sample_kurtosis,

sample_kurtosis_standard_error, sample_skew, sample_skew_standard_error,

sample_standard_deviation, sample_variance, sample_weighted_variance,

skew,

split,

standard_deviation, standard_error, sum, sum_of_inversions,

sum_of_logarithms,

sum_of_powers, sum_of_power_deviations, sum_of_squares,

sum_of_squared_deviations,

trimmed_mean, variance, weighted_mean, weighted_rms, weighted_sums,

winsorized_mean.

# Installation and download

- Install Jruby
- jruby -S gem install mdarray

# Contributors

- Contributors are welcome.

# Homepages

# HISTORY

- 16/05/2013: Version 0.5.0: All loops transfered to Java with over

50%

performance

improvement. Descriptive statistics from Parallel Colt. - 19/04/2013: Version 0.4.3: Fixes a simple (but fatal bug). No new

features - 17/04/2013: Version 0.4.2: Adds simple statistics and boolean

operators - 05/05/2013: Version 0.4.0: Initial release