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del_count = 0
for i in range(len(x)):
if not p(x[i - del_count]):
del x[i - del_count]
del_count += 1This is O(n^2)
i, n = 0, len(x)
while i != n:
if not p(x[i]):
del x[i]
n = n - 1
else:
i = i + 1std::list<Foo> x;
x.remove_if(std::not_fn(p));C++17 or later
Also works if x is an std::forward_list
Also works if x is an std::forward_list
x.RemoveAll(item => !p(item));x is List<T> (not the more general IList<T>)
x.retainWhere((e) => p);x = pack(x,.not.p())x needs to be allocatable.
j := 0
for i, v := range x {
if p(v) {
x[j] = x[i]
j++
}
}
x = x[:j]Discarded elements are overwritten.
x is resliced to its new length.
If the elements of x have a pointer type, then you should take care of a potential memory leak by setting all x[j:] elements to nil.
x is resliced to its new length.
If the elements of x have a pointer type, then you should take care of a potential memory leak by setting all x[j:] elements to nil.
func Filter[S ~[]T, T any](x *S, p func(T) bool) {
j := 0
for i, v := range *x {
if p(v) {
(*x)[j] = (*x)[i]
j++
}
}
var zero T
for k := j; k < len(*x); k++ {
(*x)[k] = zero
}
*x = (*x)[:j]
}S, T are type parameters.
In case T contains pointers, zeroing discarded elements helps garbage collection.
In case T contains pointers, zeroing discarded elements helps garbage collection.
j := 0
for i, v := range x {
if p(v) {
x[j] = x[i]
j++
}
}
for k := j; k < len(x); k++ {
x[k] = nil
}
x = x[:j]When elements of x have pointer type, it is necessary to set discarded slice elements to nil, to avoid a memory leak.
for (const [key, value] of x.entries()) {
if (!p(value)) x.splice(key, 1);
}x = x.filter((e) => p(e));x.removeIf(p.negate());x.select!(&:p)let mut j = 0;
for i in 0..x.len() {
if p(x[i]) {
x[j] = x[i];
j += 1;
}
}
x.truncate(j);