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sort: fixed bug in (Float64Slice) Less; NaN less than anything else
Previously comparisons with NaN led to contradictory results if it was compared to anything not NaN, since Less always returned false, thus breaking monotonicity of ordering. This fix makes NaN less than anything else and adds NaN and (+-)Inf to testcases. Fixes #2092. R=golang-dev, r, rsc, r CC=golang-dev https://golang.org/cl/4805051
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@ -6,6 +6,8 @@
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// collections.
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package sort
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import "math"
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// A type, typically a collection, that satisfies sort.Interface can be
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// sorted by the routines in this package. The methods require that the
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// elements of the collection be enumerated by an integer index.
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@ -167,7 +169,7 @@ func (p IntSlice) Sort() { Sort(p) }
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type Float64Slice []float64
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func (p Float64Slice) Len() int { return len(p) }
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func (p Float64Slice) Less(i, j int) bool { return p[i] < p[j] }
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func (p Float64Slice) Less(i, j int) bool { return p[i] < p[j] || math.IsNaN(p[i]) && !math.IsNaN(p[j]) }
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func (p Float64Slice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
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// Sort is a convenience method.
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@ -6,6 +6,7 @@ package sort_test
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import (
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"fmt"
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"math"
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"rand"
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. "sort"
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"strconv"
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@ -13,7 +14,7 @@ import (
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)
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var ints = [...]int{74, 59, 238, -784, 9845, 959, 905, 0, 0, 42, 7586, -5467984, 7586}
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var float64s = [...]float64{74.3, 59.0, 238.2, -784.0, 2.3, 9845.768, -959.7485, 905, 7.8, 7.8}
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var float64s = [...]float64{74.3, 59.0, math.Inf(1), 238.2, -784.0, 2.3, math.NaN(), math.NaN(), math.Inf(-1), 9845.768, -959.7485, 905, 7.8, 7.8}
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var strings = [...]string{"", "Hello", "foo", "bar", "foo", "f00", "%*&^*&^&", "***"}
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func TestSortIntSlice(t *testing.T) {
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