I have a document hash which is a reference like this: (def *document-hash* (ref (hash-map))) It looks like this {"documentid" {:term-detail {"term1" count1 ,"term2" count2}, "doclen" 33}}} How do I add to this hash table?Right now I have (defn add-doc-hash [docid term-number count] (dosync (alter *document-hash* (fn [a-h...
I want to validate a value against values retrieved from a result set's first column. I have to do the same validation operation approximately 1000 times. So, I want to decrease the time complexity of this comparison from O(n) to constant. Is there some function through which I can put all of the values of result set's column into a ...
hi, i need to insert into a very large LinkedList, whose elements i hold in a fast-access HashMap. it's important to keep the list in order (which is not the natural order of the keys). i thought it would be possible to hash the linked list nodes, then insert directly on the node (getting the node from the map + insert in a linked list...
What is the difference between the index overloaded operator and the insert method call for std::map? ie: some_map["x"] = 500; vs. some_map.insert(pair<std::string, int>("x", 500)); ...
I want to keep some totals for different accounts. In C++ I'd use STL like this: map<string,double> accounts; // Add some amounts to some accounts. accounts["Fred"] += 4.56; accounts["George"] += 1.00; accounts["Fred"] += 1.00; cout << "Fred owes me $" << accounts['Fred'] << endl; Now, how would I do the same thing in C# ? ...
I noticed in the source code for HashMap it lists the equals method as final. Why is it that when I override it I do not get a compile error? public class Test extends HashMap<Object, Object> { @Override public boolean equals(Object o) { return false; } } Java HashMap equals method: public final boolean equals(O...
Hi, I have a pretty big (100'000s of entries) HashMap. Now, I need a HashSet containing all the keys from this HashMap. Unfortunately, HashMap only has a keySet() method which returns a Set but not a HashSet. What would be an efficient way to generate such a HashSet using Java? ...
I am very new to processing.org and Java. I am trying to store objects in a HashMap, and then iterate over the values of the HashMap, calling methods on the stored objects. In order to do that, I assume I need to downcast the iterator to the type of my class, but this throws a ClassCastException ("java.util.HashMap$ValueIterator cannot b...
Hi there, I have a HashMap that I'm using in Processing and I'd like to increment the value in the map. I Google'd it and it showed me that the following code is correct: if (colors.containsKey(ckey)) { colors.put(ckey, colors.get(ckey) + 1); } else { colors.put(ckey, 1); } I keep getting: The operator + is undefined for the...
I recently discovered that the implementation of the hash map in c++ will be called unordered_map. When I looked up why they weren't just using hash_map, I discovered that apparently there are compatiblity issues with the implementation of hash_map that unordered_map resolves(http://en.wikipedia.org/wiki/Unordered_map_%28C%2B%2B%29). The...
I've been give some lovely Java code that has a lot of things like this (in a loop that executes about 1.5 million times). code = getCode(); for (int intCount = 1; intCount < vA.size() + 1; intCount++) { oA = (A)vA.elementAt(intCount - 1); if (oA.code.trim().equals(code)) currentName= oA.name; } Would I see significant in...
I was wondering what happens to the earlier values in the case of duplicate/overwritten keys. Didn't find any documentation regarding the same. Case 1: We overwrite values for a key Case 2: Duplicate key Map mymap = new HashMap(); mymap.put("1","one"); mymap.put("1","not one"); mymap.put("1","surely not one"); //the following line is ...
I have data that is organized in kind of a "key-key" format, rather than "key-value". It's like a HashMap, but I will need O(1) lookup in both directions. Is there a name for this type of data structure, and is anything like this included in Java's standard libraries? (or maybe Apache Commons?) I could write my own class that basicall...
Normally (ie. not concurrently), putAll() cannot be more efficient than using lot's of calls to put(), even assuming that you exclude the cost of building the other Map that you pass to putAll(). That's because putAll() will need to iterate the passed Map's elements, as well as running through the algorithm for adding each key value pair...
Hi, I need a kind of map which is accessible in two directions, so with a key-key structure instead of key-value. Does this exist in Java? If not, what is the best way to create it? So example: mySpecialHashMap.put("key1", "key2"); mySpecialMap.getL2R("key1") returns "key2"; mySpecialMap.getR2L("key2") returns "key1"; ...
Hello, after some years in Java and C# now I'm back to C++. Of course my programming style is influenced by those languages and I tend to feel the need of a special component that I used massively: the HASH MAP. In STL there is the hash_map, that GCC says it's deprecated and I should use unordered_map. So I turned to it. I confess I'm n...
I have working on clustering algorithm. I decided to use hashmap to store the points because thinking that i can use as clusterID and as the point. I do a dfs fashion search to identify nearest and my calculation related work and all the looping on data take place outside of the method that I identify the clusters. Also the intention...
Hi I am developing a parser that needs to put key value pairs in hashmap. But a key can have multiple values which i can do in this way HashMap<String,ArrayList<String>> . But what happens if number of keys are very large and it start matching with other key's hashcode. Will that rewrite previous key's value ? thanks -devSunday ...
Hi Have a List of array, like [[{x509Cert=x509cert.pem, accountNumber=652827, serviceProviderName=Sun, privateKey=pk, userName=0BS0Y72NBN, passWord=VuXYG4hZPS}], [{x509Cert=x509cert.pem, accountNumber=698000, serviceProviderName=Sun, privateKey=my.key, userName=0BS0Y72NAWWSS, passWord= VuXYG4hZPS}]] This was stored in an object, i got ...
I want to create a large HashMap but the put() performance is not good enough. Any ideas? Other data structure suggestions are welcome but I need the lookup feature of a Java Map: map.get(key) In my case I want to create a map with 26 million entries. Using the standard Java HashMap the put rate becomes unbearably slow after 2-3 milli...