""" A sparse matrix in COOrdinate or 'triplet' format"""

__docformat__ = "restructuredtext en"

__all__ = ['coo_matrix', 'isspmatrix_coo']

from warnings import warn

import numpy as np

from sparsetools import coo_tocsr, coo_todense, coo_matvec
from base import isspmatrix
from data import _data_matrix
from sputils import upcast, to_native, isshape, getdtype, isintlike

class coo_matrix(_data_matrix):
    """
    A sparse matrix in COOrdinate format.

    Also known as the 'ijv' or 'triplet' format.

    This can be instantiated in several ways:
        coo_matrix(D)
            with a dense matrix D

        coo_matrix(S)
            with another sparse matrix S (equivalent to S.tocoo())

        coo_matrix((M, N), [dtype])
            to construct an empty matrix with shape (M, N)
            dtype is optional, defaulting to dtype='d'.

        coo_matrix((data, ij), [shape=(M, N)])
            The arguments 'data' and 'ij' represent three arrays:
                1. data[:]   the entries of the matrix, in any order
                2. ij[0][:]  the row indices of the matrix entries
                3. ij[1][:]  the column indices of the matrix entries

            Where ``A[ij[0][k], ij[1][k] = data[k]``.  When shape is
            not specified, it is inferred from the index arrays


    Notes
    -----

    Advantages of the COO format
        - facilitates fast conversion among sparse formats
        - permits duplicate entries (see example)
        - very fast conversion to and from CSR/CSC formats

    Disadvantages of the COO format
        - does not directly support:
            + arithmetic operations
            + slicing

    Intended Usage
        - COO is a fast format for constructing sparse matrices
        - Once a matrix has been constructed, convert to CSR or
          CSC format for fast arithmetic and matrix vector operations
        - By default when converting to CSR or CSC format, duplicate (i,j)
          entries will be summed together.  This facilitates efficient
          construction of finite element matrices and the like. (see example)


    Examples
    --------

    >>> from scipy.sparse import *
    >>> from scipy import *
    >>> coo_matrix( (3,4), dtype=int8 ).todense()
    matrix([[0, 0, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 0]], dtype=int8)

    >>> row  = array([0,3,1,0])
    >>> col  = array([0,3,1,2])
    >>> data = array([4,5,7,9])
    >>> coo_matrix( (data,(row,col)), shape=(4,4) ).todense()
    matrix([[4, 0, 9, 0],
            [0, 7, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 5]])

    >>> # example with duplicates
    >>> row  = array([0,0,1,3,1,0,0])
    >>> col  = array([0,2,1,3,1,0,0])
    >>> data = array([1,1,1,1,1,1,1])
    >>> coo_matrix( (data,(row,col)), shape=(4,4)).todense()
    matrix([[3, 0, 1, 0],
            [0, 2, 0, 0],
            [0, 0, 0, 0],
            [0, 0, 0, 1]])

    """

    def __init__(self, arg1, shape=None, dtype=None, copy=False):
        _data_matrix.__init__(self)

        if isinstance(arg1, tuple):
            if isshape(arg1):
                M, N = arg1
                self.shape = (M,N)
                self.row  = np.array([], dtype=np.intc)
                self.col  = np.array([], dtype=np.intc)
                self.data = np.array([], getdtype(dtype, default=float))
            else:
                try:
                    obj, ij = arg1
                except:
                    raise TypeError('invalid input format')

                try:
                    if len(ij) != 2:
                        raise TypeError
                except TypeError:
                    raise TypeError('invalid input format')

                self.row  = np.array(ij[0], copy=copy, dtype=np.intc)
                self.col  = np.array(ij[1], copy=copy, dtype=np.intc)
                self.data = np.array(  obj, copy=copy)

                if shape is None:
                    if len(self.row) == 0 or len(self.col) == 0:
                        raise ValueError('cannot infer dimensions from zero sized index arrays')
                    M = self.row.max() + 1
                    N = self.col.max() + 1
                    self.shape = (M, N)
                else:
                    # Use 2 steps to ensure shape has length 2.
                    M, N = shape
                    self.shape = (M, N)

        elif arg1 is None:
            # Initialize an empty matrix.
            if not isinstance(shape, tuple) or not isintlike(shape[0]):
                raise TypeError('dimensions not understood')
            warn('coo_matrix(None, shape=(M,N)) is deprecated, ' \
                    'use coo_matrix( (M,N) ) instead', DeprecationWarning)
            self.shape = shape
            self.data = np.array([], getdtype(dtype, default=float))
            self.row  = np.array([], dtype=np.intc)
            self.col  = np.array([], dtype=np.intc)
        else:
            if isspmatrix(arg1):
                if isspmatrix_coo(arg1) and copy:
                    self.row   = arg1.row.copy()
                    self.col   = arg1.col.copy()
                    self.data  = arg1.data.copy()
                    self.shape = arg1.shape
                else:
                    coo = arg1.tocoo()
                    self.row   = coo.row
                    self.col   = coo.col
                    self.data  = coo.data
                    self.shape = coo.shape
            else:
                #dense argument
                try:
                    M = np.atleast_2d(np.asarray(arg1))
                except:
                    raise TypeError('invalid input format')

                if np.rank(M) != 2:
                    raise TypeError('expected rank <= 2 array or matrix')
                self.shape = M.shape
                self.row,self.col = (M != 0).nonzero()
                self.data  = M[self.row,self.col]

        if dtype is not None:
            self.data = self.data.astype(dtype)


        self._check()

    def getnnz(self):
        nnz = len(self.data)
        if nnz != len(self.row) or nnz != len(self.col):
            raise ValueError('row, column, and data array must all be the same length')

        if np.rank(self.data) != 1 or np.rank(self.row) != 1 or np.rank(self.col) != 1:
            raise ValueError('row, column, and data arrays must have rank 1')

        return nnz
    nnz = property(fget=getnnz)

    def _check(self):
        """ Checks data structure for consistency """
        nnz = self.nnz

        # index arrays should have integer data types
        if self.row.dtype.kind != 'i':
            warn("row index array has non-integer dtype (%s)  " \
                    % self.row.dtype.name )
        if self.col.dtype.kind != 'i':
            warn("col index array has non-integer dtype (%s) " \
                    % self.col.dtype.name )

        # only support 32-bit ints for now
        self.row  = np.asarray(self.row, dtype=np.intc)
        self.col  = np.asarray(self.col, dtype=np.intc)
        self.data = to_native(self.data)

        if nnz > 0:
            if self.row.max() >= self.shape[0]:
                raise ValueError('row index exceedes matrix dimensions')
            if self.col.max() >= self.shape[1]:
                raise ValueError('column index exceedes matrix dimensions')
            if self.row.min() < 0:
                raise ValueError('negative row index found')
            if self.col.min() < 0:
                raise ValueError('negative column index found')


    def transpose(self, copy=False):
        M,N = self.shape
        return coo_matrix((self.data, (self.col, self.row)), shape=(N,M), copy=copy)

    def toarray(self):
        B = np.zeros(self.shape, dtype=self.dtype)
        M,N = self.shape
        coo_todense(M, N, self.nnz, self.row, self.col, self.data, B.ravel())
        return B

    def tocsc(self):
        """Return a copy of this matrix in Compressed Sparse Column format

        Duplicate entries will be summed together.

        Example
        -------
        >>> from numpy import array
        >>> from scipy.sparse import coo_matrix
        >>> row  = array([0,0,1,3,1,0,0])
        >>> col  = array([0,2,1,3,1,0,0])
        >>> data = array([1,1,1,1,1,1,1])
        >>> A = coo_matrix( (data,(row,col)), shape=(4,4)).tocsc()
        >>> A.todense()
        matrix([[3, 0, 1, 0],
                [0, 2, 0, 0],
                [0, 0, 0, 0],
                [0, 0, 0, 1]])

        """
        from csc import csc_matrix
        if self.nnz == 0:
            return csc_matrix(self.shape, dtype=self.dtype)
        else:
            M,N = self.shape
            indptr  = np.empty(N + 1,    dtype=np.intc)
            indices = np.empty(self.nnz, dtype=np.intc)
            data    = np.empty(self.nnz, dtype=upcast(self.dtype))

            coo_tocsr(N, M, self.nnz, \
                      self.col, self.row, self.data, \
                      indptr, indices, data)

            A = csc_matrix((data, indices, indptr), shape=self.shape)
            A.sum_duplicates()

            return A

    def tocsr(self):
        """Return a copy of this matrix in Compressed Sparse Row format

        Duplicate entries will be summed together.

        Example
        -------
        >>> from numpy import array
        >>> from scipy.sparse import coo_matrix
        >>> row  = array([0,0,1,3,1,0,0])
        >>> col  = array([0,2,1,3,1,0,0])
        >>> data = array([1,1,1,1,1,1,1])
        >>> A = coo_matrix( (data,(row,col)), shape=(4,4)).tocsr()
        >>> A.todense()
        matrix([[3, 0, 1, 0],
                [0, 2, 0, 0],
                [0, 0, 0, 0],
                [0, 0, 0, 1]])

        """
        from csr import csr_matrix
        if self.nnz == 0:
            return csr_matrix(self.shape, dtype=self.dtype)
        else:
            M,N = self.shape
            indptr  = np.empty(M + 1,    dtype=np.intc)
            indices = np.empty(self.nnz, dtype=np.intc)
            data    = np.empty(self.nnz, dtype=upcast(self.dtype))

            coo_tocsr(M, N, self.nnz, \
                      self.row, self.col, self.data, \
                      indptr, indices, data)

            A = csr_matrix((data, indices, indptr), shape=self.shape)
            A.sum_duplicates()

            return A

    def tocoo(self, copy=False):
        if copy:
            return self.copy()
        else:
            return self

    def todia(self):
        from dia import dia_matrix

        ks = self.col - self.row  #the diagonal for each nonzero
        diags = np.unique(ks)

        if len(diags) > 100:
            #probably undesired, should we do something?
            #should todia() have a maxdiags parameter?
            pass

        #initialize and fill in data array
        data = np.zeros( (len(diags), self.col.max()+1), dtype=self.dtype)
        data[ np.searchsorted(diags,ks), self.col ] = self.data

        return dia_matrix((data,diags), shape=self.shape)

    def todok(self):
        from itertools import izip
        from dok import dok_matrix

        dok = dok_matrix((self.shape), dtype=self.dtype)

        dok.update( izip(izip(self.row,self.col),self.data) )

        return dok


    # needed by _data_matrix
    def _with_data(self,data,copy=True):
        """Returns a matrix with the same sparsity structure as self,
        but with different data.  By default the index arrays
        (i.e. .row and .col) are copied.
        """
        if copy:
            return coo_matrix( (data, (self.row.copy(), self.col.copy()) ), \
                                   shape=self.shape, dtype=data.dtype)
        else:
            return coo_matrix( (data, (self.row, self.col) ), \
                                   shape=self.shape, dtype=data.dtype)

    ###########################
    # Multiplication handlers #
    ###########################

    def _mul_vector(self, other):
        #output array
        result = np.zeros( self.shape[0], dtype=upcast(self.dtype,other.dtype) )
        coo_matvec(self.nnz, self.row, self.col, self.data, other, result)
        return result

    def _mul_multivector(self, other):
        return np.hstack( [ self._mul_vector(col).reshape(-1,1) for col in other.T ] )

from sputils import _isinstance

def isspmatrix_coo( x ):
    return _isinstance(x, coo_matrix)
