Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

scan a dictionary for a certain pattern

Posted on 2001-08-22
8
Medium Priority
?
259 Views
Last Modified: 2010-04-06
What is the best/easiest way for scanning a dictionary when given a certain pattern - a pattern like "ABCD" should result in a list of words like  'meat' 'fear' 'word', where a pattern like "ABAB" should result in a list of words like 'haha' 'hoho' and so on...  All help on pattern matching is very welcome.
Best regards,
Daniel
0
Comment
Question by:KinnaerD
8 Comments
 
LVL 4

Expert Comment

by:jsweby
ID: 6412451
I'm not sure about pattern matching ABCD to find any words with A,B,C or D in them, but to find a single word anywhere you can use SQL with wildcards:

SELECT Word FROM Dictionary
WHERE Word LIKE '*a*'
OR Word LIKE '*A*'

This will give you any word with a capital or lowercase A in it at any position. You can reiterate this for all the letters to search for.

J.
0
 

Author Comment

by:KinnaerD
ID: 6412573
Hi J,

This ABC-thing is the pattern which a word follows. For example, the pattern for 'there' is 'ABCDC'.  Another word that matches this pattern is 'where'.  The idea is to use a dictionary (a very long list of words) which is scanned with a given pattern (like this ABCDC) and which returns the words that fit the given pattern here 'there', 'where' ...)

regards,
Daniel
0
 
LVL 11

Expert Comment

by:robert_marquardt
ID: 6412673
As long as you use no '*' wildcard in your pattern the length of the pattern and the length of candidates must be the same.
Apart from that you will have to check all words (assuming that the words are sorted alphabetically).

The match itself is a very interesting one.
If the above pattern description is complete then it describes only equal vs unequal positional char matches.
So transform the pattern in a list of compares.

ABAB transforms to
1<>2
1= 3
1<>4
2<>3
2= 4
3<>4
This list contains unneeded compares.
Optimize it if you encounter speed problems.

Add new <> compares by substituting the other position from the = compares. Normalize the
new <> compare by having the smaller position on the left side.
Now remove all <> compares which are not unique.
In the above sample you would get 2<>3 at least twice meaning that it is implied by the other compares.
I hope this optimization is correct.
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 4

Expert Comment

by:DMN
ID: 6412817
//Here is a function... Please note! Pattern is case sensitive, word is case insensitive...
//==================================================
function match(Pattern,Word:string):Boolean;
var
  i:Integer;
  j:Integer;
begin
  Result := False;
  if Length(pattern)<>Length(Word) then  Exit;
  Word := AnsiUpperCase(Word); // Word is case insensitive, Pattern is case sensitive.
  for i:=1 to Length(Pattern) do
    for j:=1 to Length(Pattern) do
      if (Word[j]=Word[i]) xor (Pattern[i]=Pattern[j]) then
          Exit;
  Result := True;
end;
//==================================================
// That's ALL!!! Dmn. :)
//==================================================
// p.s. Nice task. Nice solution. You can even optimize it...
0
 
LVL 4

Accepted Solution

by:
DMN earned 450 total points
ID: 6412820
Oops! I make mistake in previuos comment, in FOR loop by J. It's even shorter :) Here is correct function:

function match(Pattern,Word:string):Boolean;
var
  i:Integer;
  j:Integer;
begin
  Result := False;
  if Length(pattern)<>Length(Word) then  Exit;
  Word := AnsiUpperCase(Word); // Word is case insensitive, Pattern is case sensitive.
  for i:=1 to Length(Pattern) do
    for j:=1 to i-1 do
      if (Word[j]=Word[i]) xor (Pattern[i]=Pattern[j]) then
          Exit;
  Result := True;
end;
0
 
LVL 4

Expert Comment

by:DMN
ID: 6412830
Oop's. I'm so sorry, but "FOR I" has a little mistake too... More faster solution:

function match(Pattern,Word:string):Boolean;
var
  i:Integer;
  j:Integer;
begin
  Result := False;
  if Length(pattern)<>Length(Word) then  Exit;
  Word := AnsiUpperCase(Word); // Word is case insensitive, Pattern is case sensitive.
  for i:=2 to Length(Pattern) do
    for j:=1 to i-1 do
      if (Word[j]=Word[i]) xor (Pattern[i]=Pattern[j]) then
          Exit;
  Result := True;
end;
0
 

Author Comment

by:KinnaerD
ID: 6412958
Hi DMN,

>for i:=2 to Length(Pattern) do
>   for j:=1 to i-1 do
>     if (aWord[j]=aWord[i]) xor (Pattern[i]=Pattern[j]) >then
>         Exit;
> Result := True;

thanks for this wonderful function!  As you see, I changed the variable Word into aWord.  I was fiddling with XOR as well, but your answer is the best.  Thanks.
Daniel
0
 
LVL 4

Expert Comment

by:DMN
ID: 6413005
(aWord[j]=aWord[i]) xor (Pattern[i]=Pattern[j])

is equivalent of:

(aWord[j]<>aWord[i]) and (Pattern[i]=Pattern[j])
                     or
(aWord[j]=aWord[i]) and (Pattern[i]<>Pattern[j])


Good luck!
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Hello everybody This Article will show you how to validate number with TEdit control, What's the TEdit control? TEdit is a standard Windows edit control on a form, it allows to user to write, read and copy/paste single line of text. Usua…
this video summaries big data hadoop online training demo (http://onlineitguru.com/big-data-hadoop-online-training-placement.html) , and covers basics in big data hadoop .
Want to learn how to record your desktop screen without having to use an outside camera. Click on this video and learn how to use the cool google extension called "Screencastify"! Step 1: Open a new google tab Step 2: Go to the left hand upper corn…
Suggested Courses

916 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question