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feat: add WithoutBy #515

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feat: add WithoutBy #515

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107d579
feat: add WithoutBy
nicklaus-dev Aug 15, 2024
3cf2fc4
feat: modify WithoutBy function comment
nicklaus-dev Aug 17, 2024
21f10da
feat: add WithoutBy example test
nicklaus-dev Aug 17, 2024
b968056
feat: add README
nicklaus-dev Aug 17, 2024
fd53232
feat: modify ExampleWithoutBy comments
nicklaus-dev Aug 17, 2024
4f1f56a
feat: convert Test struct to exported
nicklaus-dev Aug 18, 2024
6b9a75d
feat: fix typo
nicklaus-dev Aug 23, 2024
6e5a845
feat: impove WithoutBy performance
nicklaus-dev Aug 23, 2024
c102c03
feat: replace Without implementation by WithoutBy
nicklaus-dev Aug 23, 2024
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11 changes: 11 additions & 0 deletions intersect.go
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Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,17 @@ func Without[T comparable, Slice ~[]T](collection Slice, exclude ...T) Slice {
return result
}

// WithoutBy returns a slice excluding values whose extracted key is in the exclude list.
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This is can be a much better comment I think:

// WithoutBy filters a slice by excluding elements whose extracted keys match any in the exclude list.
// It returns a new slice containing only the elements whose keys are not in the exclude list.

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Thanks, I modifed this comments. Please review it again.

func WithoutBy[T any, K comparable](collection []T, extract func(item T) K, exclude ...K) []T {
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Can also the function def in README.

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Sure, I fixed it. Please review again.

result := make([]T, 0, len(collection))
for _, item := range collection {
if !Contains(exclude, extract(item)) {
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I'd say it's worth using sets here for better performance

func WithoutBy[T any, K comparable](collection []T, extract func(item T) K, exclude ...K) []T {
	whitelist := make(map[K]struct{}, len(collection))

	for _, item := range collection {
		whitelist[extract(item)] = struct{}{}
	}

	for _, k := range exclude {
		delete(whitelist, k)
	}

	result := make([]T, 0, len(whitelist))
	for _, item := range collection {
		if _, ok := whitelist[extract(item)]; ok {
			result = append(result, item)
		}
	}

	return result
}

Might as well refactor existing function Without

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@senago senago Aug 22, 2024 •
edited
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And maybe It would be good to simply call WithoutBy in Without, most likely compiler will optimize such a call (could check in godbolt)

func Without[T comparable](collection []T, exclude ...T) []T {
	return WithoutBy(collection, func(item T) T { return item }, exclude...)
}

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I have refactored WithoutBy function. I used blacklist to replace whitelist for code readability. It's clear now. Please review it again.

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Yeah, with blacklist it's simpler
I suggested whitelist cause this way we can preallocate the exact capacity for the resulting slice

result = append(result, item)
}
}
return result
}

// WithoutEmpty returns slice excluding empty values.
//
// Deprecated: Use lo.Compact instead.
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20 changes: 20 additions & 0 deletions intersect_test.go
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Expand Up @@ -270,6 +270,26 @@ func TestWithout(t *testing.T) {
is.IsType(nonempty, allStrings, "type preserved")
}

func TestWithoutBy(t *testing.T) {
t.Parallel()
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Can also add this in the test , This gives a more real life example:

func main() {
    // Example usage
    users := []User{
        {ID: 1, Name: "Alice"},
        {ID: 2, Name: "Bob"},
        {ID: 3, Name: "Charlie"},
    }

    // Exclude users with IDs 2 and 3
    excludedIDs := []int{2, 3}

    // Extract function to get the user ID
    extractID := func(user User) int {
        return user.ID
    }

    // Filtering users
    filteredUsers := WithoutBy(users, extractID, excludedIDs...)

    // Output the filtered users
    for _, user := range filteredUsers {
        fmt.Println(user.Name)
    }
}

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I added a intersect_example_test.go file to add this example. Please review it again.

is := assert.New(t)

type user struct {
name string
age int
}

result1 := WithoutBy([]user{{name: "nick"}, {name: "peter"}},
func(item user) string {
return item.name
}, "nick", "lily")
result2 := WithoutBy([]user{}, func(item user) int { return item.age }, 1, 2, 3)
result3 := WithoutBy([]user{}, func(item user) string { return item.name })
is.Equal(result1, []user{{name: "peter"}})
is.Equal(result2, []user{})
is.Equal(result3, []user{})
}

func TestWithoutEmpty(t *testing.T) {
t.Parallel()
is := assert.New(t)
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