public static void main(String[] args) {
// stream.collect(collector): values
// Collectors.groupingBy(classifier)
Stream<Locale> locales = Stream.of(Locale.getAvailableLocales());
Map<String, List<Locale>> languageToLocales =
locales.collect(Collectors.groupingBy(Locale::getDisplayLanguage));
System.out.println(languageToLocales);
System.out.println("--------------");
// stream.collect(collector): values
// Collectors.groupingBy(classifier, downstream)
locales = Stream.of(Locale.getAvailableLocales());
Map<String, Long> languageToLocalesCounting =
locales.collect(Collectors.groupingBy(Locale::getDisplayLanguage, Collectors.counting()));
System.out.println(languageToLocalesCounting);
System.out.println("--------------");
// stream.collect(collector): values
// Collectors.partitioningBy(predicate)
locales = Stream.of(Locale.getAvailableLocales());
Map<Boolean, List<Locale>> englishAndOtherLocales =
locales.collect(Collectors.partitioningBy(l -> l.getLanguage().equals("en")));
List<Locale> englishLocales = englishAndOtherLocales.get(true);
System.out.println(englishLocales);
System.out.println("--------------");
}
public static void main(String[] args) {
List<Participante> participantes = ParticipantesTdc.listaTodos();
// Operações Simples
participantes.stream().count();
boolean participantInscrito = participantes.stream().anyMatch(Participante::isInscrito);
Optional<String> optionalEmail2 = participantes.stream().map(Participante::getEmail).findAny();
// Collectors
List<String> emailsList =
participantes.stream().map(Participante::getEmail).collect(Collectors.toList());
List<String> emailsLinkedList =
participantes
.stream()
.map(Participante::getEmail)
.collect(Collectors.toCollection(LinkedList::new));
Set<String> emailsSet =
participantes.stream().map(Participante::getEmail).collect(Collectors.toSet());
Map<TamanhoCamisa, List<Participante>> participantesPorTamanho =
participantes.stream().collect(Collectors.groupingBy(Participante::getTamanhoCamisa));
Map<TamanhoCamisa, List<String>> emailsPorTamanho =
participantes
.stream()
.collect(
Collectors.groupingBy(
Participante::getTamanhoCamisa,
Collectors.mapping(Participante::getEmail, Collectors.toList())));
}
public Map<Championship, Map<Season, List<HockeyMatch>>>
groupAllMatchesByChampionshipAndSeasons() {
List<HockeyMatch> all = findAll();
Map<Championship, Map<Season, List<HockeyMatch>>> collect =
all.stream()
.collect(
Collectors.groupingBy(
HockeyMatch::getChampionship, Collectors.groupingBy(HockeyMatch::getSeason)));
return collect;
}
public static void main(String[] args) {
final List<Person> people =
Arrays.asList(
new Person("Robert", 49),
new Person("John", 20),
new Person("Sara", 21),
new Person("Chloe", 18),
new Person("Jane", 21),
new Person("Greg", 35));
List<Person> olderThan20_a = new ArrayList<>();
people.stream().filter(person -> person.age > 20).forEach(person -> olderThan20_a.add(person));
printPeople("don't trust olderThan20_a", olderThan20_a);
List<Person> olderThan20_b =
people
.stream()
.filter(person -> person.age > 20)
.collect(ArrayList::new, ArrayList::add, ArrayList::addAll);
printPeople("don't trust olderThan20_b", olderThan20_b);
List<Person> olderThan20_c =
people.stream().filter(person -> person.age > 20).collect(Collectors.toList());
printPeople("don't trust olderThan20_c", olderThan20_c);
Map<Integer, List<Person>> peopleByAge =
people.stream().collect(Collectors.groupingBy(person -> person.age));
System.out.println("Grouped by age: " + peopleByAge);
Map<Integer, List<String>> nameOfPeopleByAge =
people
.stream()
.collect(
Collectors.groupingBy(
person -> person.age,
Collectors.mapping(person -> person.name, Collectors.toList())));
System.out.println("People grouped by age: " + nameOfPeopleByAge);
// Group the names by their first char and then get the oldest person in
// each group
Comparator<Person> byAge = Comparator.comparing(person -> person.age);
Map<Character, Optional<Person>> oldestPersonOfEachLetter =
people
.stream()
.collect(
Collectors.groupingBy(
person -> person.name.charAt(0),
Collectors.reducing(BinaryOperator.maxBy(byAge))));
System.out.println("Oldest person of each letter:");
System.out.println(oldestPersonOfEachLetter);
}
private Availability firstAssignation(AID alumn) {
if (this.groups.containsKey(alumn)) {
System.err.println("WARN: Requested first assignation for already registered alumn " + alumn);
return this.groups.get(alumn);
}
// TODO: This could be more optimized, for example, having the
// availabilityCount map cached
// Get the count of the current availabilities
final Map<Availability, Long> availabilityCount =
this.groups.values().stream().collect(Collectors.groupingBy(a -> a, Collectors.counting()));
// Get the current available groups
final List<Availability> availableGroups =
TeacherBehaviour.AVAILABLE_GROUPS
.stream()
.filter(
a -> availabilityCount.getOrDefault(a, 0l) < TeacherBehaviour.MAX_ALUMNS_PER_GROUP)
.collect(Collectors.toList());
// Pick a random one
final Availability result = availableGroups.get(this.random.nextInt(availableGroups.size()));
this.groups.put(alumn, result);
return result;
}
@Test
public void vote() throws Exception {
ObjectMapper mapper = new ObjectMapper();
Restaurant restaurantB =
mapper.readValue(new StringReader(testRestaurantJson1), Restaurant.class);
restaurantRepository.saveAndFlush(restaurantB);
Restaurant restaurantA =
mapper.readValue(new StringReader(testRestaurantJson2), Restaurant.class);
restaurantRepository.saveAndFlush(restaurantA);
doVote(restaurantB.getRestaurantName(), "qqq");
doVote(restaurantB.getRestaurantName(), "www");
doVote(restaurantB.getRestaurantName(), "ddd");
doVote(restaurantA.getRestaurantName(), "kkk");
doVote(restaurantA.getRestaurantName(), "lll");
List<Vote> votes = votesRepository.findAll();
// check all votes are here
assertEquals(MAX_TOTAL_VOTES, votes.size());
Map<Long, Long> res =
votes.stream().collect(Collectors.groupingBy(Vote::getRestaurantId, Collectors.counting()));
// check all votes counter correctly
assertEquals(3l, res.get(restaurantB.getId()).longValue());
assertEquals(2l, res.get(restaurantA.getId()).longValue());
}
public static void main(String[] args) {
Map<Integer, HashSet<String>> withSet =
Stream.of("jon", "andrew", "harvey", "bil")
.collect(Collectors.groupingBy(String::length, HashSet::new));
out.println(withSet);
}
@Test
public void testMapping() {
List<String> input = Arrays.asList("Capital", "lower", "Foo", "bar");
Collector<String, ?, Map<Boolean, Optional<Integer>>> collector =
MoreCollectors.partitioningBy(
str -> Character.isUpperCase(str.charAt(0)),
MoreCollectors.mapping(String::length, MoreCollectors.first()));
checkShortCircuitCollector(
"mapping", new BooleanMap<>(Optional.of(7), Optional.of(5)), 2, input::stream, collector);
Collector<String, ?, Map<Boolean, Optional<Integer>>> collectorLast =
MoreCollectors.partitioningBy(
str -> Character.isUpperCase(str.charAt(0)),
MoreCollectors.mapping(String::length, MoreCollectors.last()));
checkCollector(
"last", new BooleanMap<>(Optional.of(3), Optional.of(3)), input::stream, collectorLast);
input = Arrays.asList("Abc", "Bac", "Aac", "Abv", "Bbc", "Bgd", "Atc", "Bpv");
Map<Character, List<String>> expected =
EntryStream.of('A', Arrays.asList("Abc", "Aac"), 'B', Arrays.asList("Bac", "Bbc")).toMap();
AtomicInteger cnt = new AtomicInteger();
Collector<String, ?, Map<Character, List<String>>> groupMap =
Collectors.groupingBy(
s -> s.charAt(0),
MoreCollectors.mapping(
x -> {
cnt.incrementAndGet();
return x;
},
MoreCollectors.head(2)));
checkCollector("groupMap", expected, input::stream, groupMap);
cnt.set(0);
assertEquals(expected, input.stream().collect(groupMap));
assertEquals(4, cnt.get());
}
/**
* Process supported manifest headers (Startup-Component and Provide-Capability).
*
* <p>Process Startup-Component headers and create StartupComponent instances.
*
* <p>Process Provide-Capability headers to calculate the expected number of required
* capabilities.
*
* <p>Process Provide-Capability headers to get a list of CapabilityProviders and
* RequiredCapabilityListeners.
*
* @param bundleList list of bundles to be scanned for Provide-Capability headers.
* @param supportedManifestHeaders list of manifest headers processed by this method.
*/
private void processManifestHeaders(
List<Bundle> bundleList, List<String> supportedManifestHeaders) {
Map<String, List<ManifestElement>> groupedManifestElements =
bundleList
.stream()
// Filter out all the supported manifest headers.
.filter(
bundle ->
AccessController.doPrivileged(
(PrivilegedAction<Boolean>)
() ->
isSupportedManifestHeaderExists(bundle, supportedManifestHeaders)))
// Process filtered manifest headers and get a list of ManifestElements.
.flatMap(bundle -> extractManifestElements(bundle, supportedManifestHeaders).stream())
// Partition all the ManifestElements with the manifest header name.
.collect(Collectors.groupingBy(ManifestElement::getValue));
if (groupedManifestElements.get(STARTUP_LISTENER_COMPONENT) != null) {
processStartupComponents(groupedManifestElements.get(STARTUP_LISTENER_COMPONENT));
}
if (groupedManifestElements.get(OSGI_SERVICE_COMPONENT) != null) {
processOSGiServiceCapabilities(groupedManifestElements.get(OSGI_SERVICE_COMPONENT));
}
// You can add logic to handle other types of provide capabilities here.
// e.g. custom manifest headers, config files etc.
}
private List<LDObject> mergeLocations(List<LDObject> ldObjects) {
Map<String, List<LDObject>> r =
ldObjects
.stream()
.parallel()
.collect(
Collectors.groupingBy(
ldObject -> {
return ldObject.getMap().get("locationId").getValues().get(0);
}));
List<LDObject> finalLocationForJourney = new ArrayList<>();
final LDObject[] finalObj = {null};
r.forEach(
(k, v) -> {
v.stream()
.forEach(
ldObject -> {
if (finalObj[0] == null) {
finalObj[0] = ldObject;
} else {
finalObj[0].merge(ldObject);
}
});
finalLocationForJourney.add(finalObj[0]);
finalObj[0] = null;
});
return finalLocationForJourney;
}
public static void main(String[] args) {
final Collection<Task> tasks =
Arrays.asList(
new Task(Status.OPEN, 5), new Task(Status.OPEN, 13), new Task(Status.CLOSED, 8));
// 在这个task集合中一共有多少个OPEN状态的点？在Java 8之前，要解决这个问题，则需要使用foreach循环遍历task集合；但是在Java
// 8中可以利用steams解决：包括一系列元素的列表，并且支持顺序和并行处理。
final long totalPointsOfOpenTasks =
tasks
.stream()
.filter(task -> task.getStatus() == Status.OPEN)
.mapToInt(Task::getPoints)
.sum();
System.out.println("Total points: " + totalPointsOfOpenTasks);
/**
* Steam之上的操作可分为中间操作和晚期操作。
*
* <p>中间操作会返回一个新的steam——执行一个中间操作（例如filter）并不会执行实际的过滤操作，而是创建一个新的steam，
* 并将原steam中符合条件的元素放入新创建的steam。
*
* <p>晚期操作（例如forEach或者sum），会遍历steam并得出结果或者附带结果；在执行晚期操作之后，steam处理线已经处理完毕，
* 就不能使用了。在几乎所有情况下，晚期操作都是立刻对steam进行遍历。
*/
// steam的另一个价值是创造性地支持并行处理（parallel processing）。对于上述的tasks集合，我们可以用下面的代码计算所有任务的点数之和：
// Calculate total points of all tasks
final double totalPoints =
tasks
.stream()
.parallel()
.map(task -> task.getPoints()) // or map( Task::getPoints )
.reduce(0, Integer::sum);
System.out.println("Total points (all tasks): " + totalPoints);
// 对于一个集合，经常需要根据某些条件对其中的元素分组。利用steam提供的API可以很快完成这类任务，代码如下：
// Group tasks by their status
final Map<Status, List<Task>> map =
tasks.stream().collect(Collectors.groupingBy(Task::getStatus));
System.out.println(map);
// 最后一个关于tasks集合的例子问题是：如何计算集合中每个任务的点数在集合中所占的比重，具体处理的代码如下：
// Calculate the weight of each tasks (as percent of total points)
final Collection<String> result =
tasks
.stream() // Stream< String >
.mapToInt(Task::getPoints) // IntStream
.asLongStream() // LongStream
.mapToDouble(points -> points / totalPoints) // DoubleStream
.boxed() // Stream< Double >
.mapToLong(weigth -> (long) (weigth * 100)) // LongStream
.mapToObj(percentage -> percentage + "%") // Stream< String>
.collect(Collectors.toList()); // List< String >
System.out.println(result); // [19%, 50%, 30%]
}
@Test
public void _11_그룹핑() {
final Stream<Locale> stream = Stream.of(Locale.getAvailableLocales());
Map<String, List<Locale>> countryToLocales =
stream.collect(
Collectors.groupingBy(Locale::getCountry) // 묶을 기준값
);
System.out.println(countryToLocales.get("CH"));
}
@Test
public void gruppiereNachNachnamen() {
Map<String, List<Person>> gruppiertNachNachnamen =
newPersonenStream() //
.collect(Collectors.groupingBy(Person::getNachname));
assertThat(gruppiertNachNachnamen.keySet(), hasSize(100));
assertThat(gruppiertNachNachnamen.get("Müller"), hasSize(1000));
assertThat(gruppiertNachNachnamen.get("Schuster"), hasSize(1000));
}
private void checkResults(Restaurant restA, Restaurant restB) {
List<Vote> votes = votesRepository.findAll();
// check changing vote doesn't create new entries
assertEquals(MAX_TOTAL_VOTES, votes.size());
Map<Long, Long> res =
votes.stream().collect(Collectors.groupingBy(Vote::getRestaurantId, Collectors.counting()));
// check that vote actually changed
assertEquals(2l, res.get(restB.getId()).longValue());
assertEquals(3l, res.get(restA.getId()).longValue());
}
/**
* Run time: O(n) can use bit vector also
*
* @param input
* @return
*/
static boolean hasUnique(String input) {
if (input == null || input.isEmpty()) return true;
Map<Character, Long> map =
input
.chars()
.mapToObj(c -> (char) c)
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
return !map.entrySet().stream().anyMatch(x -> x.getValue() > 1);
}
void buildInMem() {
Collection<EntityType> data = dataSrcFun.apply(dataSrc);
java.util.Map<String, Set<String>> setMap =
data.stream()
.collect(
Collectors.groupingBy(
e -> keyToStringFun.apply(keyGetFun.apply(e)),
Collectors.mapping(
e -> memberToStringFun.apply(memberGetFun.apply(e)), Collectors.toSet())));
setMapAdapter.putInMem(mapName, setMap);
}
public static void main(String[] args) {
final List<Person> people =
Arrays.asList(
new Person("John", 20),
new Person("Sara", 21),
new Person("Jane", 21),
new Person("Greg", 35));
List<Person> olderThan20 =
people
.stream()
.filter(person -> person.getAge() > 20)
.collect(ArrayList::new, ArrayList::add, ArrayList::addAll);
System.out.println("People older than 20: " + olderThan20);
List<Person> olderThan20_1 =
people.stream().filter(person -> person.getAge() > 20).collect(Collectors.toList());
System.out.println("People older than 20: " + olderThan20_1);
Map<Integer, List<Person>> peopleByAge =
people.stream().collect(Collectors.groupingBy(Person::getAge));
System.out.println("Grouped by age: " + peopleByAge);
Map<Integer, List<String>> nameOfPeopleByAge =
people
.stream()
.collect(
Collectors.groupingBy(
Person::getAge, Collectors.mapping(Person::getName, Collectors.toList())));
System.out.println("People name grouped by age: " + nameOfPeopleByAge);
Comparator<Person> byAge = Comparator.comparing(Person::getAge);
Map<Character, Optional<Person>> oldestPersonOfEachCharacter =
people
.stream()
.collect(
Collectors.groupingBy(
person -> person.getName().charAt(0),
Collectors.reducing(BinaryOperator.maxBy(byAge))));
System.out.println("Oldest person of each letter: " + oldestPersonOfEachCharacter);
}
public static void main(String[] args) {
Map<Long, Long> collect =
IntStream.range(0, 10)
.mapToObj(Long::valueOf)
.collect(Collectors.groupingBy(i -> i, reducing((a, b) -> a)));
System.out.println(collect);
Map<Long, Long> collect2 =
IntStream.range(0, 10).mapToObj(Long::valueOf).collect(Collectors.toMap(i -> i, i -> i));
System.out.println(collect2);
}
public Graph(String line) {
map =
Arrays.stream(
(line.trim() + " " + new StringBuilder(line.trim()).reverse().toString())
.split(" "))
.collect(
Collectors.groupingBy(
x -> ((String) x).charAt(0),
Collectors.mapping(
x -> ((String) x).charAt(1),
Collectors.toCollection(LinkedHashSet<Character>::new))));
}
public void restore(boolean writeMode, Long manifestIdDefault) {
List<CmsCIRelation> watchedBys;
long counter = 0;
long restoredMonitors = 0;
if (manifestIdDefault == null) {
watchedBys =
cmProcessor.getCIRelationsNsLikeNakedNoAttrs("/", "manifest.WatchedBy", null, null, null);
} else {
watchedBys = cmManager.getFromCIRelations(manifestIdDefault, "manifest.WatchedBy", null);
}
long startTime = System.currentTimeMillis();
Map<Long, List<CmsCIRelation>> monitors =
watchedBys.stream().collect(Collectors.groupingBy(CmsCIRelation::getFromCiId));
for (Long manifestId : monitors.keySet()) {
counter++;
List<CmsCIRelation> realizedAsRels =
cmManager.getFromCIRelations(manifestId, "base.RealizedAs", null);
if (realizedAsRels.isEmpty()) continue;
Set<Long> cmsBomCiIds =
realizedAsRels.stream().map(CmsCIRelation::getToCiId).collect(Collectors.toSet());
restoreRealizedAsMapping(manifestId, cmsBomCiIds, writeMode);
boolean isFirstBom = true;
for (CmsCIRelation relation : realizedAsRels) {
restoreManifestMapping(manifestId, relation.getToCiId(), writeMode);
if (isFirstBom) {
for (CmsCIRelation rel : monitors.get(manifestId)) {
if (rel.getToCi() == null) {
rel.setToCi(cmProcessor.getCiById(rel.getToCiId()));
}
if (restoreMonitor(manifestId, relation.getToCiId(), rel.getToCi(), writeMode)) {
restoredMonitors++;
}
}
}
isFirstBom = false;
}
if (counter % 100 == 0) {
logger.info(
"Time to process "
+ counter
+ " - "
+ (System.currentTimeMillis() - startTime)
+ " ms!");
}
}
logger.info(">>>>>>>>>>> Monitor restored " + restoredMonitors + ";");
logger.info(
">>>>>>>>>>> Monitor restoration is done!!!"
+ counter
+ " - "
+ (System.currentTimeMillis() - startTime)
+ " ms!");
}
/**
* Build TrendContent with external services top by average response time.
*
* @param period
* @param limit
* @param timeRange
* @param transactions
* @param transactionsStatistic
* @return
*/
public static TrendContext<String> topByAvgResponseTime(
Long period,
Integer limit,
TimeRange timeRange,
Iterable<ExternalService> transactions,
Iterable<ExternalServiceStatistic> transactionsStatistic) {
TrendContext<String> trendContext = new TrendContext<>(period * 1000, timeRange);
Map<Long, ExternalService> externalServiceMap =
StreamSupport.stream(transactions.spliterator(), false)
.collect(Collectors.toMap(ExternalService::getId, (t) -> t));
Map<String, List<ExternalServiceStatistic>> transactionStatisticMap =
StreamSupport.stream(transactionsStatistic.spliterator(), false)
.collect(
Collectors.groupingBy(
statistic -> {
Long serviceId = statistic.getExternalServiceId();
ExternalService transaction = externalServiceMap.get(serviceId);
return transaction.getUrl();
}));
transactionStatisticMap
.entrySet()
.stream()
.sorted(
Comparator.comparing(
new Function<Map.Entry<String, List<ExternalServiceStatistic>>, Double>() {
@Override
public Double apply(Map.Entry<String, List<ExternalServiceStatistic>> entry) {
DoubleSummaryStatistics responseSummaryStatistics =
entry
.getValue()
.stream()
.filter(statistic -> statistic.getSumResponseTime() != null)
.mapToDouble(ExternalServiceStatistic::getSumResponseTime)
.summaryStatistics();
LongSummaryStatistics pvSummaryStatistics =
entry
.getValue()
.stream()
.filter(statistic -> statistic.getPv() != null)
.mapToLong(ExternalServiceStatistic::getPv)
.summaryStatistics();
return calculateRate(
responseSummaryStatistics.getSum(), pvSummaryStatistics.getSum());
}
}))
.limit(limit)
.forEach(entry -> trendContext.addStatistics(entry.getKey(), timeRange, entry.getValue()));
return trendContext;
}
@Benchmark
public void parallel_lazy_jdk() {
Map<Alphagram, List<String>> groupBy =
this.guavaWords.parallelStream().collect(Collectors.groupingBy(Alphagram::new));
groupBy
.entrySet()
.parallelStream()
.map(Map.Entry::getValue)
.filter(list -> list.size() >= SIZE_THRESHOLD)
.sorted(Comparator.<List<String>>comparingInt(List::size).reversed())
.map(list -> list.size() + ": " + list)
.forEach(e -> Assert.assertFalse(e.isEmpty()));
}
@RequestMapping("/gameStatus")
public ResponseEntity<GameStatus> broadcastGameStatus() {
GameStatus gameStatus = new GameStatus();
Iterable<GameStep> gameSteps = gameStepRepository.findAll();
List<GameStep> collect = StreamSupport.stream(gameSteps.spliterator(), false).collect(toList());
Map<String, List<GameStep>> gameStepByUser =
StreamSupport.stream(gameSteps.spliterator(), false)
.collect(Collectors.groupingBy(GameStep::getUserPseudo));
for (Map.Entry<String, List<GameStep>> gameStepByUserEntry : gameStepByUser.entrySet()) {
UserGameStatus userGameStatus = new UserGameStatus();
userGameStatus.setPseudo(gameStepByUserEntry.getKey());
Map<Step, List<GameStep>> gameStepByStep =
gameStepByUserEntry.getValue().stream().collect(Collectors.groupingBy(GameStep::getStep));
for (Map.Entry<Step, List<GameStep>> gameStepByStepEntry : gameStepByStep.entrySet()) {
gameStepByStepEntry
.getValue()
.stream()
.min(Comparator.comparing(GameStep::getInstant))
.ifPresent(
gameStep -> {
userGameStatus
.getStepInfos()
.add(new StepInfo(gameStep.getStep(), gameStep.getInstant()));
});
}
gameStatus.getUserGameStatus().add(userGameStatus);
}
webSocketTemplate.convertAndSend("/topic/gameStatus", gameStatus);
return new ResponseEntity<GameStatus>(gameStatus, HttpStatus.OK);
}
@Test
public void testCollectors() {
ArrayList<Person> people = new ArrayList<>();
ArrayList<Integer> things = new ArrayList<>();
ArrayList<Employee> employees = new ArrayList<>();
ArrayList<Student> students = new ArrayList<>();
// Accumulate names into a List
List<String> list = people.stream().map(Person::getName).collect(Collectors.toList());
// Accumulate names into a TreeSet
Set<String> list2 =
people.stream().map(Person::getName).collect(Collectors.toCollection(TreeSet::new));
// Convert elements to strings and concatenate them, separated by commas
String joined = things.stream().map(Object::toString).collect(Collectors.joining(", "));
// Find highest-paid employee
Optional<Employee> highestPaid =
employees.stream().collect(Collectors.maxBy(Comparator.comparingInt(Employee::getSalary)));
// Group employees by department
Map<Department, List<Employee>> byDept =
employees.stream().collect(Collectors.groupingBy(Employee::getDepartment));
// Find highest-paid employee by department
Map<Department, Optional<Employee>> highestPaidByDept =
employees
.stream()
.collect(
Collectors.groupingBy(
Employee::getDepartment,
Collectors.maxBy(Comparator.comparingInt(Employee::getSalary))));
// Partition students into passing and failing
Map<Boolean, List<Student>> passingFailing =
students.stream().collect(Collectors.partitioningBy(s -> s.getGrade() >= PASS_THRESHOLD));
}
/**
* Returns a partitioned collection of lane number to Tile objects from the provided basecall
* directory.
*/
public static Map<Integer, ? extends Collection<Tile>> readLaneTiles(
final File illuminaRunDirectory, final ReadStructure readStructure) {
final Collection<Tile> tiles;
try {
tiles =
TileMetricsUtil.parseTileMetrics(
TileMetricsUtil.renderTileMetricsFileFromBasecallingDirectory(illuminaRunDirectory),
readStructure);
} catch (final FileNotFoundException e) {
throw new PicardException("Unable to open laneMetrics file.", e);
}
return tiles.stream().collect(Collectors.groupingBy(Tile::getLaneNumber));
}
// Good reading: https://en.wikipedia.org/wiki/Permutation
private static double numOfPerms(int[] seq) {
// Note that the sequence may potentially have repeating elements
Map<Integer, Long> freq =
Arrays.stream(seq)
.boxed()
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
// https://en.wikipedia.org/wiki/Permutation#Permutations_of_multisets
double numOfPerms = factorial(seq.length);
for (long uniqElemFreq : freq.values()) {
// according to the problem description, max size of permutation is in [2..18] range
numOfPerms /= factorial((int) uniqElemFreq);
}
return numOfPerms;
}
@Benchmark
public void serial_lazy_streams_ec() {
Map<Alphagram, Set<String>> groupBy =
this.ecWords
.stream()
.collect(Collectors.groupingBy(Alphagram::new, Collectors.<String>toSet()));
groupBy
.entrySet()
.stream()
.map(Map.Entry::getValue)
.filter(list -> list.size() >= SIZE_THRESHOLD)
.sorted(Comparator.<Set<String>>comparingInt(Set::size).reversed())
.map(list -> list.size() + ": " + list)
.forEach(e -> Assert.assertFalse(e.isEmpty()));
}
@RequestMapping("/events/{eventName}/additional-field")
public List<TicketFieldConfigurationAndAllDescriptions> getAllAdditionalField(
@PathVariable("eventName") String eventName) {
final Map<Integer, List<TicketFieldDescription>> descById =
ticketFieldRepository
.findDescriptions(eventName)
.stream()
.collect(Collectors.groupingBy(TicketFieldDescription::getTicketFieldConfigurationId));
return ticketFieldRepository
.findAdditionalFieldsForEvent(eventName)
.stream()
.map(
field ->
new TicketFieldConfigurationAndAllDescriptions(
field, descById.getOrDefault(field.getId(), Collections.emptyList())))
.collect(Collectors.toList());
}
@Cacheable(value = "KLineBuss.queryAllGroup")
public List<KLineGroup> queryAllGroup() {
Map<Date, Map<String, KLine>> kLineMap =
kLineRepos
.findAll()
.stream()
.collect(
Collectors.groupingBy(
KLine::getDt, Collectors.toMap(KLine::getCode, kLine -> kLine)));
List<KLineGroup> list =
kLineMap
.entrySet()
.stream()
.map(entry -> new KLineGroup(entry.getKey(), entry.getValue()))
.sorted()
.collect(Collectors.toList());
return Collections.unmodifiableList(list);
}
static Map<String, MatchedDataPair> matchData(
DataSource xSource,
MergeType xMergeType,
DataSource ySource,
MergeType yMergeType,
Resolution resolution) {
List<String> commonKeys =
xSource
.getData()
.keySet()
.stream()
.filter((key) -> ySource.getData().containsKey(key))
.map(resolution::toKey)
.distinct()
.collect(Collectors.toList());
Function<DataSource, Map<String, List<Double>>> dataOrganizer =
(source) ->
source
.getData()
.entrySet()
.stream()
.filter((entry) -> commonKeys.contains(resolution.toKey(entry)))
.collect(
Collectors.groupingBy(
(entry) -> resolution.toKey(entry),
Collectors.mapping((entry) -> entry.getValue(), Collectors.toList())));
Map<String, List<Double>> xData = dataOrganizer.apply(xSource);
Map<String, List<Double>> yData = dataOrganizer.apply(ySource);
Map<String, MatchedDataPair> matches =
commonKeys
.stream()
.collect(
Collectors.<String, String, MatchedDataPair>toMap(
key -> key,
key ->
new MatchedDataPair(
xMergeType.merge(xData.get(key)), yMergeType.merge(yData.get(key)))));
return matches;
}
