• Experience using a third-party spell program
• Developing efficient methods for accomplishing autocomplete

In the previous document (AutocompleteInSolr.pdf) you saw how to enhance the Solr program with spelling correction and an autocomplete (suggest) function. In this exercise you are asked to use an external spelling correction program in conjunction with Solr and to enhance the autocomplete functionality of Solr. For spelling correction, you may use an existing third-party program adapted to your downloaded files. In the case of autocomplete you will need to enhance your client program that communicates with Solr to deliver autocomplete suggestions to the web interface you created in an earlier homework Description of the Exercise

Spelling Correction: in the class lecture you saw a complete spelling correction program developed by Peter Norvig. The program was written in Python. For this exercise you are welcome to use whatever third-party spelling program you wish, or you may even write your own. Since most of you wrote your previous homework client using PhP, you may want to adopt a version of Norvigs spelling program written in PhP and run it on your server. You can download the PhP version of Norvigs spelling corrector from here:

http://www.phpclasses.org/package/4859PHPSuggestcorrectedspellingtextinpurePHP.html#download

(you will have to register at the site before being able to download the software, registration is free)

If you prefer to use Norvigs program in a different language, a wide variety of implementations can be found at the bottom of this page, http://norvig.com/spellcorrect.html

You should make sure to enhance your spelling correction program with a set of terms that are specific to the news website that you are responsible for. You should make sure that common terms such as climate, election, etc., and the terms used in the queries of homework #4 are handled. Norvigs spell correction program uses a text file(big.txt) to get set of words to calculate edit distance. For this you should create your own big.txt for your specified news website. You can use any parser (our suggestion Apache Tika) and Instructions on using apache Tika for this purpose can be found here, (https://tika.apache.org/1.5/gettingstarted.html

).

Autocomplete: for the autocomplete portion of the exercise, you will have to modify your client program, so it accepts single character insertions to the text box, and returns a list of completions/suggestions.

There are several ways to implement the autocomplete functionality while using Solr. One possible way is to use the FuzzyLookupFactory

(https://lucene.apache.org/solr/guide/6_6/suggester.html) feature of Solr/Lucene. The FuzzyLookupFactory creates suggestions for misspelled words in fields. It assumes that what youre sending as the suggest.query parameter is the beginning of the suggestion. It will match terms in your index starting with the provided characters. So, if the query is ca it will return all the words starting with ca, e.g. california and carolina etc. For the first character and second character that is entered, some autocomplete suggestions should appear.

For this to work you need to enable the suggest component as described in the tutorial but add some options.

Note: with respect to specific issues about how spelling corrections are displayed or how autocomplete corrections are displayed you should imitate the way Google handles both. For example, while typing in the search box, the top suggestions should automatically appear and be updated as the user keeps typing. The spellcheck suggestion should appear at the top of the retrieved results. If the word typed is correct no suggestion should appear at the top.

Note 1:

Suggested config change for making AND as default instead of OR for multi-word queries in solr:

Solr default boolean model uses OR instead of AND. So, if your query is Elon Musk, then the result will match all pages which either have Elon OR Musk present and not the entire query Elon Musk.To solve this problem, please do as following to set up the standard Query Parser Parameters:

In solrconfig.xml add this line: <str name=q.op>AND</str> within this tag: <requestHandler name=/select class=solr.SearchHandler> and Inside <lst> default tag within requestHandler tag: <lst name=defaults> Remember to reload after editing.

FAQs

Q1. Can we use default spell checker for HW5?

5. You are not supposed to use default spell-checker for Hw5.

Q2. How to handle multi word queries?

1. To handle queries with two words, please handle each word separately.

Q3. Can we use solrs inbuilt auto-complete features? A. Yes.

Q4. How should the spell correction and auto complete working look like.

1. Imitate googles auto complete and spell correction, your result should look like that

Q5. when using the php corrector and when loading big.txt, error log says allowed memory size exhausted.

1. Add the following code, <? php ini_set (memory_limit, 1024M)?> at the start of your php file. This should solve it. If it still doesnt, change the code to <? php ini_set (memory_limit, 1)?>

Q6. Do we need to store users history for suggestions?

1. A. No need to store any user history to get this functionality.

Q7. Do we need to extract the data from all the 17000+ files into big.txt and do we have to avoid duplicates?

1. A. Yes, you need to extract the content from all your files. Please Dont avoid duplicates, please read how Norvigs spell correction works, you will find why you need to have duplicates.

Q8. In hw4 it tells us to set the text to have a type of text general. However, in hw5 it says text_en_splitting.

A.You can leave as it is. It works just fine.

Q9. Solr exception: Java.lang.String cannot be cast to Java.lang.String

1. please check whether you added suggest component as stated in document(at right place and with right tags).

Q10. How does big.txt look like?

1. You need to parse content of html files into big.txt. Please refer to http://norvig.com/big.txt.

Q11. Do we need to extract the data from all the 17000+ files into big.txt and do we have to avoid duplicates?

1. A. Yes, you need to extract the content from all your files. Please Dont avoid duplicates, please read how Norvigs spell correction works, If you de-duplicate, then you will defeat the purpose of using word frequency to estimate P(c), where c is the corrected spelling.

Q12. The document SpellcheckandAutocompletioninSolr.pdf is only for reference? For both spellcheck and autocompletion we dont use the solr internal functions? We both use external ones?

1. A. #1 for spell check: You use external program

#2 for Auto completion: You use the one inbuilt in solr.

Q13. If we search Donad Trup, when we put Donad, the spell check should show Donald, what if we put Donad Trup, what spell check should show? Should we combine each spell check result, like Donald Trump, or just show Donad Trump, only correct the correct word?

1. A. Please check for each word separately when you have multiple words in query. You need not get right spell check for every query you enter. Please have right big.txt will all text as per your news site. We will take care while grading.

Q14. Can we use the big.txt provided on the Norvigs website and add query terms from hw4 into it, or do we have to generate ourselves with Tika?

1. A. Please generate it. It doesnt make sense to load all the words from The adventures of sherlock Holmes in to memory. You might not get correct results too.

Q15. Can we remove the radio button and functionality of page rank here for hw5? A. No. You can leave it as it was for Hw4.

Q16. I did not do the pagination function on my page. Can we just do top ten results? A. Pagination is NOT a requirement for this exercise. Top 10 should suffice.

Q17. How should the UI look for auto-suggest feature?

1. Try to imitate the way google works. There should be a dropdown of suggestions when a character is entered. Also, the suggestions should be clickable. Once a suggestion is clicked, it should replace the text in the text box.

Q18. Mimicking Google Spell Correction

1. Google handles spelling correction in 2 ways. You can follow any one from the below 2 approaches
2. Show result for misspelled word. Just below the text box, you can display the correct spelling which is clickable. Upon clicking the correct word, it should perform a search and display the new results.
3. Show results for the spell corrected term. Just below the text box, display the spell corrected term and the initial misspelled term. Make the misspelled term clickable. Upon clicking, it should perform a search and display the new results.