Suppose I tell my Java program to find the subject of the sentence:
I enjoy spending time with my family.
My program should output:
Tell me more about your family.
How would it go about doing this?
EDIT
I could do this by having an array of String and have that filled with every noun in the English dictionary, but is there a simpler way?
This is way too open-ended a question. But a good place to start would be to learn about Natural Language Processing concepts and then look at using a framework like CoreNLP. It breaks down sentences into a parse tree and you can use this to identify parts of speech and things like the subject of a sentence. This is probably your best bet if you want a reasonably-reliable method.
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I have a program that is randomly generating sentences based on a bunch of text documents of all the nouns, verbs, adjectives, and adverbs. Does anyone know a way to determine if a noun/verb are plural or singular, or if there any text documents that contain a list of singular nouns/verbs and plural nouns? I'm doing this all in Java, and I have a decent idea of how to get information off of a website, so if there are any websites that could do that as well, I'd also appreciate those.
I am afraid, you cannot solve this by having a fixed list of words, especially verbs. Consider sentences:
You are free. We are free.
In the first one, are is singular, it is plural. Using a proper tagger as #jdaz suggests is the only way how you can do it in a reliable way.
If you work with English or a few other supported languages, StanfordNLP is an excellent choice. If you need a broad language coverage, you can use UDPipe that is natively in C++ but has a Java binding.
The first step would be to look it up in a list. For English you can reduce the size of the list by only including singular nouns, and then apply some basic string processing to find plurals: if your word ends in -s and is not in the list, cut off the -s and look again. If it now is in the list, it was a simple plural (car/cars). If not, continue. If it ends in -ies, remove that, append -y and look again. Now you will capture remedies/remedy. There are a number of such patterns you can use.
Some irregular nouns need to be in an exception list (ox/oxen), but there aren't that many. Some words of course are unspecified, like sheep, data, or police. Here you need to look at the context: if the noun is followed by a singular verb (eg eats, or is), then it would be singular as well.
With (English) verbs you can generally only identify the third person singular (with a similar procedure as used for nouns; you's need a list of exceptions for verbs anding in -s (such as kiss)). Forms of to be are more helpful, but the second person singular is an issue (are). However, unless you have direct speech in your texts, it will not be used very frequently.
Part of speech taggers can also only make these decisions on context, so I don't think they will be much of a help here. It's likely to be overkill. A couple of word lists and simple heuristic rules will probably give you equal or better accuracy using far fewer resources. This is the way these things were done before large amounts of annotated data were available.
In the end it depends on your circumstances. It might be quicker to simply use an existing tagger, but for this limited problem you might get better accuracy and speed with the rule-based approach, (or even a combined one for accuracy).
I have been going through the Java interview questions asked by my company and came across one that I can't seem to find the solution.
Here is the question:
Please write a method (function) accepting as single parameter a
string and reversing the order of the words in this string.
The " " is the word separator and any other char is considered as being part of a word. In order to simplify, please consider that there is always one space between the words.
Important - You are NOT allowed to use other strings or arrays or other data structures containing several elements - just plain atomic variables such as integers, chars etc.
Also, it is not allowed to use any other language specific string function other than the function giving you the length of the string.
Expected result:
"hello my beautiful world" -> "world beautiful my hello"
So, I can't use: chars[], str.split(), str.charAt(), str.substring(), StringBuilder, another declaration of String.
Should I use recursion to do it?
Since, String is Immutable and uses encapsulation,
There is no solution to your problem. You can't update the values directly, no setters are available and without the access to the getters (since you can only use .length), you can't read the value.
So, I would suggest to respond that Immutability and encapsulation prevent you from doing so.
In real life as a software engineer, you'll sometimes be asked to do things that are technically impossible or even nonsensical. Sometimes the person asking will be someone important like your boss or a big customer.
If someone actually asks you this interview question, then you're in one of those situations. That makes this question pretty interesting, and you might want to figure out what the best way to answer really is.
If someone asked me, this is how I would answer, and as an interviewer, this is the kind of answer I would award the most points for:
1) Explain how it's technically impossible to meet the requirements, but do it without making me feel stupid. This shows diplomacy.
2) Figure out what I really want. In this case, the interviewer probably wants to see if you know how to reverse the words in a string using low-level operations. This is a perfectly reasonable C language question, for example. Figuring out what the interviewer really wants shows experience and judgement.
3) Provide an answer that gives me what I want. Write this method in Java, but take a StringBuilder instead of a string, and call only length(), charAt(), and setCharAt(). This shows the expertise that the interviewer wants to see.
Now this is a tricky problem for which I'm not able to figure out a good solution. Suppose we have a String in Java:- "He ate 3 apples today." Now the digit 3 can be easily identified in Java using isNumeric function or using regular expressions. But what if I have a String like: "He ate three apples today."? How can I identify that three is actually a number? I used OpenNlp and used its POS tagger but the time it takes to do is really too much! Can anyone suggest a better solution for this? Also among the ".bin" of OpenNlp, there is one file-"num.bin", but I don't know how to use this file. OpenNlp documentation also say nothing about it. Can anyone tell me if this is exactly what I've been looking for, and if yes then how to use it.
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I'm actually short of time here, so I've settled on a temporary solution here. Make a file/dictionary and take all the entries in a hashtable. Then I'll tokenize my sentence and check word by word for numbers, similar to what you guys suggested. I'll keep on updating the file as and when required. Thanks for your valuable suggestions guys, and if you have got something better than this I'd be really glad. OpenNlp implements this in a very good way, the only problem with it is time complexity and I want to do this in minimum time possible.
Create a dictionary of numbers. Search for elements from that dictionary in the text.
Check asympotic complexity, it may be cheaper to sort the text first.
You have to keep all that words in arrays and then use it. Here is an example how to convert number to string. It may help you... I think you have to split your text into words and check if a word is a number (three). If yes check the next word because it can be say "million", then check the next word and so on. It's not easy and seems like a little library.I think you'll spend a lot of time writing this. Or try to search in google for a library like this. Maybe someone have already got this problem, wrote a library and shares it for free )) Good luck.
The following list contains 1 correct word called "disastrous" and other incorrect words which sound like the correct word?
A. disastrus
B. disasstrous
C. desastrous
D. desastrus
E. disastrous
F. disasstrous
Is it possible to automate generation of wrong choices given a correct word, through some kind of java dictionary API?
No, there is nothing related in java API. You can make a simple algorithm which will do the job.
Just make up some rules about letters permutations and doubling and add generated words to the Set until you get enough words.
There are a number of algorithms for matching words by sound - 'soundex' is the one that springs to mind, but I remember uncovering a few when I did some research on this a couple of years ago. I expect the problem you would find is that they take a word and return a value that represents how the word sounds so you can see if two spellings sound similar (so the words in the question should generate similar values); but I expect doing the reverse, i.e. taking the value and generating similar sounding spellings, would be quite hard.
I worked the last 5 days to understand how unification algorithm works in Prolog .
Now ,I want to implement such algorithm in Java ..
I thought maybe best way is to manipulate the string and decompose its parts using some datastructure such as Stacks ..
to make it clear :
suppose user inputs is:
a(X,c(d,X)) = a(2,c(d,Y)).
I already take it as one string and split it into two strings (Expression1 and 2 ).
now, how can I know if the next char(s) is Variable or constants or etc.. ,
I can do it by nested if but it seems to me not good solution ..
I tried to use inheritance but the problem still ( how can I know the type of chars being read ?)
First you need to parse the inputs and build expression trees. Then apply Milner's unification algorithm (or some other unification algorithm) to figure out the mapping of variables to constants and expressions.
A really good description of Milner's algorithm may be found in the Dragon Book: "Compilers: Principles, Techniques and Tools" by Aho, Sethi and Ullman. (Milners algorithm can also cope with unification of cyclic graphs, and the Dragon Book presents it as a way to do type inference). By the sounds of it, you could benefit from learning a bit about parsing ... which is also covered by the Dragon Book.
EDIT: Other answers have suggested using a parser generator; e.g. ANTLR. That's good advice, but (judging from your example) your grammar is so simple that you could also get by with using StringTokenizer and a hand-written recursive descent parser. In fact, if you've got the time (and inclination) it is worth implementing the parser both ways as a learning exercise.
It sounds like this problem is more to do with parsing than unification specifically. Using something like ANTLR might help in terms of turning the original string into some kind of tree structure.
(It's not quite clear what you mean by "do it by nested", but if you mean that you're doing something like trying to read an expression, and recursing when meeting each "(", then that's actually one of the right ways to do it -- this is at heart what the code that ANTLR generates for you will do.)
If you are more interested in the mechanics of unifying things than you are in parsing, then one perfectly good way to do this is to construct the internal representation in code directly, and put off the parsing aspect for now. This can get a bit annoying during development, as your Prolog-style statements are now a rather verbose set of Java statements, but it lets you focus on one problem at a time, which is usually helpful.
(If you structure things this way, this should make it straightforward to insert a proper parser later, that will produce the same sort of tree as you have until then been constructing by hand. This will let you attack the two problems separately in a reasonably neat fashion.)
Before you get to do the semantics of the language, you have to convert the text into a form that's easy to operate on. This process is called parsing and the semantic representation is called an abstract syntax tree (AST).
A simple recursive descent parser for Prolog might be hand written, but it's more common to use a parser toolkit such as Rats! or Antlr
In an AST for Prolog, you might have classes for Term, and CompoundTerm, Variable, and Atom are all Terms. Polymorphism allows the arguments to a compound term to be any Term.
Your unification algorithm then becomes unifying the name of any compound term, and recursively unifying the value of each argument of corresponding compound terms.