That's a simple beta version of a multi-dimensional array library for Lua 5.3.
We are in the final stage of the design and I really appreciate any feedbacks about the user interface
and functionalities. The aim is to release the more productive library as possible.
iota_marray
===========
Fast Multi-Dimensional Arrays for Lua (BETA VERSION)
An multi-dimensional (marray) is a common numeric array with a specific size but indexed by n numbers. We can create a new marray with 2 dimensions (rank 2) and size 6000 in Lua with
local ima = require"marray"
ma = ima.new(10, 20, 30)
that can be read/write from the traditional syntax
for i=1,ma.dim[1] do
for j=1,ma.dim[2] do
for k=1,ma.dim[3] do
ma[i][j][k] = math.random()
end
end
end
where we have made use of the dimensions attribute. We note that marrays have more two intrinsic attributes, namely, ma.rank and ma.size, with obviosly meaning.
The marrays also possess some basic mathematical attributes, you can perform some operations on two identical size marrays, for example
mb = ia.new(10, 600)
mb = ma*3.0
mb = ma - 0.5*mb
are all valid operations, but the result is not so obviouly!
To be more funny the marrays also possess a regular Lua table that can be indexed
ma.name = 'say hello :'
ma.HI = function() return 'HI!' end
then print(ma.name, ma.HI()) will print
say hello : HI!
RESHAPE
We can use the reshape facility
ia.reshape(mb, 10*600)
such that mb is now indexed with 1 index, and initialize very easy
for i=1,mb.dim[1] do
mb[i] = math.random()
end
After the assigmentent, we can reshape again
is.reshape(mb, 10, 600)
to obtain the original shape. You can always reshape a marray, but do not change its size.
SLICES AND VIEWS
The reshape is very funny, but what if we need a sub-portion of the marray? simple, slice it!
v1 = ia.slice(ma, 2, 10)
yields a new VIEW, with rank = mb.rank-1 such that va[i][j] equals ma[i][10][k]. We can also specify an 'end' and 'step' options to slice, such that
v2 = ia.slice(ma, 3, 10, 20, 5)
creates a view with the same rank as mb, but the third dimension goes from 10 to 20 with steps of 5, namely,
v2[i][j][1] == ma[i][j][10]
v2[i][j][2] == ma[i][j][15]
v2[i][j][3] == ma[i][j][20]
with i=1,mb.dim[1] and j=1,mb.dim[2] and k=1,2,3, and the respective dimensions are updated, then
for i=1,v2.dim[1] do
for j=1,v2.dim[2] do
for k=1,v2.dim3[3] do
v2[i][j][k] = math.random()
end
end
end
is also valid. Indexed marrays/views are also 'sliceable',
v3 = ia.toview(ma[5][10])
is such that
v3[i] == ma[5][10][i]
The views always 'remember' the orinal shape of the marray, then you can reshape your marray
ia.reshape(ma, 6000)
and v3[i], v2[i][j][k] and v1[i][j] access to the same numbers as before!
Finally, v3.name == ma.name !
TODO
Index check, I do not check any index.
Mathematical operations on views.
More?
To compile you need a (c)BLAS library!
--
Rodrigo Azevedo Moreira da Silva
