github.com/aarzilli/tools@v0.0.0-20151123112009-0d27094f75e0/sort/subsort/02-int.go (about)

     1  package subsort
     2  
     3  import "sort"
     4  
     5  type SortedByIntVal struct {
     6  	IdxOrig int // index of the original slice
     7  	Val     int // dynamically filled value to be sorted by
     8  }
     9  
    10  type sliceSortableIntAsc []SortedByIntVal
    11  type sliceSortableIntDesc []SortedByIntVal
    12  
    13  func (s sliceSortableIntAsc) Len() int {
    14  	return len(s)
    15  }
    16  
    17  func (s sliceSortableIntAsc) Swap(i, j int) {
    18  	s[i], s[j] = s[j], s[i]
    19  }
    20  
    21  func (s sliceSortableIntAsc) Less(i, j int) bool {
    22  	if s[i].Val < s[j].Val {
    23  		return true
    24  	}
    25  	return false
    26  }
    27  func (s sliceSortableIntDesc) Len() int {
    28  	return len(s)
    29  }
    30  
    31  func (s sliceSortableIntDesc) Swap(i, j int) {
    32  	s[i], s[j] = s[j], s[i]
    33  }
    34  
    35  func (s sliceSortableIntDesc) Less(i, j int) bool {
    36  	if s[i].Val > s[j].Val {
    37  		return true
    38  	}
    39  	return false
    40  }
    41  
    42  //
    43  // A second way only requires the callee
    44  // only to submit a func, that extracts the sort value by index:
    45  type ExtractIntFielder func(i int) int
    46  
    47  //
    48  // An interface ExtractIntFielder, would require all callee slices to be wrapped.
    49  func SortByIntValAsc(size int, f ExtractIntFielder) []SortedByIntVal {
    50  
    51  	copyOfSubset := make([]SortedByIntVal, size)
    52  	for i := 0; i < size; i++ {
    53  		copyOfSubset[i].IdxOrig = i
    54  		copyOfSubset[i].Val = f(i)
    55  	}
    56  
    57  	wrapperSortable := sliceSortableIntAsc(copyOfSubset)
    58  	sort.Sort(wrapperSortable)
    59  	unwrap := []SortedByIntVal(wrapperSortable)
    60  	return unwrap
    61  
    62  }
    63  func SortByIntValDesc(size int, f ExtractIntFielder) []SortedByIntVal {
    64  
    65  	copyOfSubset := make([]SortedByIntVal, size)
    66  	for i := 0; i < size; i++ {
    67  		copyOfSubset[i].IdxOrig = i
    68  		copyOfSubset[i].Val = f(i)
    69  	}
    70  
    71  	wrapperSortable := sliceSortableIntDesc(copyOfSubset)
    72  	sort.Sort(wrapperSortable)
    73  	unwrap := []SortedByIntVal(wrapperSortable)
    74  	return unwrap
    75  
    76  }