TEST(ZipNode, TwoDisbalancedStringArrays) {
// first DIA is heavily balanced to the first workers, second DIA is
// balanced to the last workers.
std::function<void(Context&)> start_func =
[](Context& ctx) {
// generate random strings with 10..20 characters
auto input_gen = Generate(
ctx,
[](size_t index) -> std::string {
std::default_random_engine rng(
123456 + static_cast<unsigned>(index));
std::uniform_int_distribution<size_t> length(10, 20);
rng(); // skip one number
return common::RandomString(
length(rng), rng, "abcdefghijklmnopqrstuvwxyz")
+ std::to_string(index);
},
test_size);
DIA<std::string> input = input_gen.Cache();
std::vector<std::string> vinput = input.AllGather();
ASSERT_EQ(test_size, vinput.size());
// Filter out strings that start with a-e
auto input1 = input.Filter(
[](const std::string& str) { return str[0] <= 'e'; });
// Filter out strings that start with w-z
auto input2 = input.Filter(
[](const std::string& str) { return str[0] >= 'w'; });
// zip
auto zip_result = input1.Zip(
input2, [](const std::string& a, const std::string& b) {
return a + b;
});
// check result
std::vector<std::string> res = zip_result.AllGather();
// recalculate result locally
std::vector<std::string> check;
{
std::vector<std::string> v1, v2;
for (size_t index = 0; index < vinput.size(); ++index) {
const std::string& s1 = vinput[index];
if (s1[0] <= 'e') v1.push_back(s1);
if (s1[0] >= 'w') v2.push_back(s1);
}
ASSERT_EQ(v1, input1.AllGather());
ASSERT_EQ(v2, input2.AllGather());
for (size_t i = 0; i < std::min(v1.size(), v2.size()); ++i) {
check.push_back(v1[i] + v2[i]);
// sLOG1 << check.back();
}
}
for (size_t i = 0; i != res.size(); ++i) {
sLOG0 << res[i] << " " << check[i] << (res[i] == check[i]);
}
ASSERT_EQ(check.size(), res.size());
ASSERT_EQ(check, res);
};
api::RunLocalTests(start_func);
}
ValueType Select(const DIA<ValueType, InStack>& data, size_t rank,
const Compare& compare = Compare()) {
api::Context& ctx = data.context();
const size_t size = data.Size();
assert(0 <= rank && rank < size);
if (size <= base_case_size) {
// base case, gather all data at worker with rank 0
ValueType result = ValueType();
auto elements = data.Gather();
if (ctx.my_rank() == 0) {
assert(rank < elements.size());
std::nth_element(elements.begin(), elements.begin() + rank,
elements.end(), compare);
result = elements[rank];
LOG << "base case: " << size << " elements remaining, result is "
<< result;
}
result = ctx.net.Broadcast(result);
return result;
}
ValueType left_pivot, right_pivot;
std::tie(left_pivot, right_pivot) = PickPivots(data, size, rank, compare);
size_t left_size, middle_size, right_size;
using PartSizes = std::pair<size_t, size_t>;
std::tie(left_size, middle_size) =
data.Map(
[&](const ValueType& elem) -> PartSizes {
if (compare(elem, left_pivot))
return PartSizes { 1, 0 };
else if (!compare(right_pivot, elem))
return PartSizes { 0, 1 };
else
return PartSizes { 0, 0 };
})
.Sum(
[](const PartSizes& a, const PartSizes& b) -> PartSizes {
return PartSizes { a.first + b.first, a.second + b.second };
},
PartSizes { 0, 0 });
right_size = size - left_size - middle_size;
LOGM << "left_size = " << left_size << ", middle_size = " << middle_size
<< ", right_size = " << right_size << ", rank = " << rank;
if (rank == left_size) {
// all the elements strictly smaller than the left pivot are on the left
// side -> left_size-th element is the left pivot
LOGM << "result is left pivot: " << left_pivot;
return left_pivot;
}
else if (rank == left_size + middle_size - 1) {
// only the elements strictly greater than the right pivot are on the
// right side, so the result is the right pivot in this case
LOGM << "result is right pivot: " << right_pivot;
return right_pivot;
}
else if (rank < left_size) {
// recurse on the left partition
LOGM << "Recursing left, " << left_size
<< " elements remaining (rank = " << rank << ")\n";
auto left = data.Filter(
[&](const ValueType& elem) -> bool {
return compare(elem, left_pivot);
}).Collapse();
assert(left.Size() == left_size);
return Select(left, rank, compare);
}
else if (left_size + middle_size <= rank) {
// recurse on the right partition
LOGM << "Recursing right, " << right_size
<< " elements remaining (rank = " << rank - left_size - middle_size
<< ")\n";
auto right = data.Filter(
[&](const ValueType& elem) -> bool {
return compare(right_pivot, elem);
}).Collapse();
assert(right.Size() == right_size);
return Select(right, rank - left_size - middle_size, compare);
}
else {
// recurse on the middle partition
LOGM << "Recursing middle, " << middle_size
<< " elements remaining (rank = " << rank - left_size << ")\n";
auto middle = data.Filter(
[&](const ValueType& elem) -> bool {
return !compare(elem, left_pivot) &&
!compare(right_pivot, elem);
}).Collapse();
assert(middle.Size() == middle_size);
return Select(middle, rank - left_size, compare);
}
}