intmat.go

package villa

import (
	"fmt"

	"github.com/golangplus/bytes"
)

/*
IntMatrix is 2D array of integers. Elements are store in a single int slice and slices of each row are created.

NOTE the matrix can be sized of 0x0, but never 0x10 or 10x0.
*/
type IntMatrix [][]int

// NewIntMatrix creates a new IntMatrix instance with specified number of rows and columns
func NewIntMatrix(nRow, nCol int) IntMatrix {
	s := make([]int, nCol*nRow)
	mat := make(IntMatrix, nRow)
	for i, p := 0, 0; i < nRow; i++ {
		mat[i] = s[p : p+nCol]
		p += nCol
	}

	return mat
}

// Clone clones an IntMatrix
func (m IntMatrix) Clone() IntMatrix {
	mat := NewIntMatrix(m.Rows(), m.Cols())

	n := m.Rows() * m.Cols()
	if n > 0 {
		copy(mat[0][:n], m[0][:n])
	}

	return mat
}

// Cols returns the number of columns
func (m IntMatrix) Cols() int {
	if len(m) == 0 {
		return 0
	}

	return len(m[0])
}

// Rows returns the number of rows
func (m IntMatrix) Rows() int {
	return len(m)
}

// PrettyString returns a pretty text form of the matrix.
// This function is mainly for debugging.
func (m IntMatrix) PrettyString() string {
	sa := make([][]string, 0, m.Rows())
	for _, row := range m {
		sr := make([]string, 0, len(row))
		for _, cell := range row {
			sr = append(sr, fmt.Sprint(cell))
		}
		sa = append(sa, sr)
	}

	wds := make([]int, m.Cols())
	for i := 0; i < m.Rows(); i++ {
		for j := 0; j < m.Cols(); j++ {
			if len(sa[i][j]) > wds[j] {
				wds[j] = len(sa[i][j])
			}
		}
	}

	var res bytesp.Slice
	for i, row := range sa {
		if i == 0 {
			res.WriteString("[")
		} else {
			res.WriteString(" ")
		}
		res.WriteString("[")
		for j, cell := range row {
			if j > 0 {
				res.WriteString(" ")
			}
			fmt.Fprintf(&res, "%*s", wds[j], cell)
		}
		res.WriteString("]")
		if i == len(sa)-1 {
			fmt.Fprintf(&res, "](%dx%d)", m.Rows(), m.Cols())
		}
		res.WriteString("\n")
	}

	return string(res)
}

// Fill sets all elements of the matrix to a specified value
func (m IntMatrix) Fill(vl int) {
	if len(m) == 0 {
		return
	}

	n := m.Rows() * m.Cols()
	IntSlice(m[0][:n]).Fill(0, n, vl)
}