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See:
Description
Interface Summary | |
---|---|
Filter<T> | Filter is an interface for predicate objects which respond to the
accept method. |
PriorityQueue<E> | A Set that also represents an ordering of its elements, and responds
quickly to add() , changePriority() ,
removeFirst() , and getFirst() method calls. |
Class Summary | |
---|---|
AbstractIterator<E> | Iterator with remove() defined to throw an
UnsupportedOperationException . |
ArrayMap<K,V> | ArrayMap: A map that is backed by an Array |
BinaryHeapPriorityQueue<E> | PriorityQueue with explicit double priority values. |
EntryValueComparator | Comparator designed for the values of Map entries. |
Index<E> | An Index is a collection that maps between an Object vocabulary and a contiguous non-negative integer index beginning (inclusively) at 0. |
IntPair | |
IntQuadruple | |
IntTriple | |
IntTuple | A tuple of int. |
IntUni | Just a single integer |
MapFactory | A factory class for vending different sorts of Maps. |
MutableDouble | A class for Double objects that you can change. |
MutableInteger | A class for Integer objects that you can change. |
Pair<T1,T2> | Pair: A Class for holding a pair of objects. |
Sets | Utilities for sets |
StringUtils | StringUtils is a class for random String things, including output formatting and command line argument parsing. |
Timing | A class for measuring how long things take. |
XMLUtils | Class XMLUtils |
XMLUtils.XMLTag |
A collection of useful general-purpose utility classes. Below is a selection of some of the most useful utility classes, along with a brief description and sample use. Consult the class comments for more details on any of these classes.
edu.stanford.nlp.util.Counter
Specialized Map for storing numeric counts for objects. Makes it easy to get/set/increment the count of an object and find the max/argmax. Also makes it easy to prune counts above/below a threshold and get the total count of all or a subset of the objects. Exposes a Comparator that can sort the keySet or entrySet by count.
Some useful methods:
argmax
,averageCount
,comparator
,incrementCount
,keysAbove(threshold)
,max
,normalize
,totalCount
Example: generate a unigram language model for a Document with low counts (<3 counts) pruned:
Counter wordProbs = new Counter();
for(int i = 0; i < document.size(); i++) {
wordProbs.incrementCount(document.get(i));
wordProbs.removeAll(wordProbs.keysBelow(3)); // prune low counts
wordProbs.normalize(); // convert to probability distributionExample: find the Integer param that yields the best value of some
computeScore
method (that returns an int or double):
Counter paramScores = new Counter();
for(int param=0; param<10; param++) {
paramScores.setCount(new Integer(param), computeScore(param));
Integer bestParam=(Integer)paramScores.argmax();
edu.stanford.nlp.util.Filter
Interface to accept or reject Objects. A Filter implements
boolean accept(Object obj)
. This can represent any binary predicate, such as "lowercase Strings", "numbers above a threshold", "trees where a VP dominates an NP and PP", and so on. Particularly useful in conjunction withFilters
, which contains some basic filters as well as a method for filtering an array of Objects or a Collection. Another example is Counter'stotalCount(Filter)
, which returns the sum of all counts in the Counter whose keys pass the filter.
edu.stanford.nlp.util.Filters
Static class with some useful
Filter
implementations and utility methods for working with Filters. Contains Filters that always accept or reject, Filters that accept or reject an Object if it's in a given Collection, as well as several composite Filters. Contains methods for creating a new Filter that is the AND/OR of two Filters, or the NOT of a Filter. You can make a Filter that runs a givenAppliable
on all Objects before comparing them--this is useful when you have a collection of complex objects and you want to accept/reject based on one of their sub-objects or method values. Finally, you can filter an Object[] through a Filter to return a newObject[]
with only the accepeted values, orretainAll
elements in a Collection that pass a Filter.Some useful methods:
andFilter(Filter, Filter)
,collectionAcceptFilter(Collection)
,filter(Object[], Filter)
,retainAll(Collection, Filter)
,transformedFilter(Filter, Appliable)
Example: Filter an array of Strings to retain only those with length less than 10:
Filter filter = new Filter() {
public boolean accept(Object obj) {
return (((String)obj).length < 10);
String[] shortStrings = (String[])Filters.filter(allStrings, filter);
edu.stanford.nlp.util.EntryValueComparator
Comparator for sorting Map keys and entries. If you use the empty Constructor, this Comparator will compare
Map.Entry
objects by comparing their values. If you pass aMap
into the constructor, the Comparator can sort either the Map's keySet or entrySet. You can also pass anascending
flag to optionally reverse natural sorting order.Sort a Map's keys by their values (descending order):
List keys = new ArrayList(map.keySet());
Collections.sort(keys, new EntryValueComparator(map, false));Sort a Map's entries by their values (normal order):
List entries = new ArrayList(map.entrySet());
Collections.sort(entries, new EntryValueComparator());
edu.stanford.nlp.util.Index
List that also maintains a constant-time reverse-lookup of indices for its Objects. Often one uses a List to associate a unique index with each Object (e.g. controlled vocbulary, feature map, etc.). Index offers constant-time performance for both i
ndex -> Object
(get
) andObject -> index
(indexOf
) as well as forcontains(Object)
. Otherwise it behaves like a normal list. Index also supportslock()
andunlock()
to ensure that it's only modified when desired. Another useful method isint[] indices(List elems)
, which maps each elem to its index.Some useful methods:
add(Object)
,contains(Object)
,get(index)
,indexOf(Object)
,lock()
edu.stanford.nlp.util.StringUtils
Static class with lots of useful String manipulation and formatting methods. Many of these methods will be familiar to perl users:
join
,split
,trim
,find
,lookingAt
, andmatches
. There are also useful methods for padding Strings/Objects with spaces on the right or left for printing even-width table columns:leftPad
,pad
. Finally, there are convenience methods for reading in all the text in a File or at a URL:slurpFile
,slurpURL
, as well as a method for making a "clean" filename from a String (where all spaces are turned into hyphens and non-alphanum chars become underscores):fileNameClean
.Example: print a comma-separated list of numbers:
System.out.println(StringUtils.pad(nums, ", "));
Example: print a 2D array of numbers with 8-char cells:
for(int i = 0; i < nums.length; i++) {
for(int j = 0; j < nums[i].length; j++) {
System.out.print(StringUtils.leftPad(nums[i][j], 8));
System.out.println();
Example: get a List of lines in a file (ignoring blank lines):
String fileContents = StringUtils.slurpFile(new File("filename"));
List lines = StringUtils.split(fileContents, "[\r\n]+");
edu.stanford.nlp.util.Timing
Static class for measuring how long something takes to execute. To use, call
startTime
before running the code in question. Calltick
to print an intermediate update, andendTime
to finish the timing and print the result. You can optionally pass a descriptive string andPrintStream
totick
andendTime
for more control over what gets printed where.Example: time reading in a big file and transforming it:
Timing.startTime();
String bigFileContents = StringUtils.slurpFile(bigFile);
Timing.tick("read in big file", System.err);
String output = costlyTransform(bigFileContents);
Timing.endTime("transformed big file", System.err);
Other packages with some useful utilies
edu.stanford.nlp.io
edu.stanford.nlp.process
edu.stanford.nlp.stats
edu.stanford.nlp.swing
edu.stanford.nlp.web
Questionable classes in util
Numberer: this is sort of a duplicate of Index, but adds a level of namespaces on top. But it's widely used and doesn't quite seem worth removing.
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