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[KingSparta]

I was hoping you might know an answer to this.

lets say i have a database (comma delimited) and i need to look for something quick. get the data and get out how would you do that?

right now i am using input to read the database when it finds what it needs then jump out.

is there a faster way?

[RhinoBanga]

Hi Dude,

There are loads of ways you can speed it up but I need some more info before I can answer:

1)  How many records in the file?
2)  Does the file contents change often?
3)  Is each record in the file a fixed length (I presume not)?


Answer these and I'll be able to give you a more definative answer.

You can also contact me on RhinoBanga@hotmail.com via MSN if you want to realtime chat.

[KingSparta]

>> 1) How many records in the file?
16194

>> 2) Does the file contents change often?
No, It Would Never Change Unless More Top 40 Lines Were Added in Excel

>> 3) Is each record in the file a fixed length (I presume not)?
Nope

I was thinking this morning to make this faster, i could get this info in A MSFlexGrid, read it once, and then Search It somehow (not sure how one would do that, since i never messed with this before).

A Sample Of The Info In the Database (Songname, Artist, Year, ChartPos)

Zorba the Greek, Herb Alpert & The Tijuana Brass, 1966, 11

[RhinoBanga]

Since you are using VB I'd:

1)  Load the data into a listview ... each subitem is a field.
2)  When you want to do a search sort by the subitem in question and perform a binary chop search of the listview records.

That will guarentee that it will only take up to a maximum of 14 reads to find the entry you are after.

If you don't know about binary chopping let me know and I'll explain it to you.

[KingSparta]

>> 2) When you want to do a search sort by the subitem in question
>> and perform a binary chop search of the listview records.
Easy For You To Say

>> perform a binary chop search
Not A Clue

I Did Pull Up A ListView Just to check it out

I did not find anything in the help about "Binary Chop Search" however

[KingSparta]

Been doing some reading about list view

there is a search option

FindItem string, value, index, match

Value, index, match are all optional.

a sample is

Set LItem = ListView1.FindItem(FindItem, LvwText,  , Lvwpartial)

i guess that would find something, then i guess i could somehow use that and somehow tell it to get the data from the 4 boxes in the listview.

I guess?

[RhinoBanga]

Don't worry dude ... binary chopping is a concept.

It means with a sorted list you can take the number of records and find the middle record.   If the value you are looking for is less than the one at this position then you can discard the data beyon that record.   If it's greater then you can discard anything below it.   You repeat this until you find you data.



For example say you had 5 records containing two fields like so:

DEF        456
ABC        123
JKL        012
GHI        789
MNO        345


Now if you wanted to find GHI, traditionally you would do a sequential (or linear) search and you would find it at after 4 reads.

If you sorted the data first, e.g.:

ABC        123
DEF        456
GHI        789
JKL        012
MNO        345

And then performed a "Binary Chop" of the data you would find it in ONE read, e.g.:

1)  Find the middle point ... which is record 3
2)  Compare to the search criteria ... it matches so you are done.


Say you wanted to find MNO:

1)  Find the middle point ... which is record 3
2)  Compare to the search criteria ... it's greater than so can discard records 1, 2 and 3.
3)  Find the middle point in the remaining records ... since there's only two you take the lower entry
3)  Compare to the search criteria ... it's greater than so can discard records 4.
4)  Since you now only have one left you can compare ... and it matches.


So with the unsorted data it would have taken 5 reads ... with binary chopping it takes 3.



Just apply this concept with the listview.   Add the records, sort by the field you want, then manually perform the binary chop looking for your data.

[RhinoBanga]

I think the problem with the FindItem method is that it's still a linear search.

[KingSparta]

I see what your saying now...

I will do some more research and build a demo to see if i can get something working

You Would Not Have A Sample To Look At Would You?

:-)

I Asked You Since You Tend To Be Smarter Than Me.

[RhinoBanga]

I don't have a sample dude but if you get stuck email me your demo and I'll look at it for you.


P.S.  It's nothing to do with being smarter ... it's just I've been programming for nearly 20 years now ... so I've been around the block so to speak

[KingSparta]

hehehe

I hear you...

Thanks For Pointing Me In The Right Direction.

Later


PS: Something I Found


Public Type demBC
  keyValue as String * 10
  targetValue as String * 50
End Type
Public BCArray() as demBC

Public Function BinaryChop(SearchValue as String) as Long
  Dim StopPoint As Long, LowPoint As Long, HighPoint As Long
  Dim ChopCount As Long, ChopPoint As Long
  Dim ElemCnt as Long
  Dim Check1 As String, Check2 As String
  Const ValueNotFound = -32767

  ArrayStart = LBound(BCArray())
  ArrayEnd = UBound(BCARRAY())
  If LBound(BCArray()) < 0 then
      ElemCnt = Abs(LBound(BCArray())) |PLS| Abs(UBound(BCArray())) |PLS| 1
  Else
      ElemCnt = UBound(BCArray()) - LBound(BCArray()) |PLS| 1
  End If
  StopPoint = 1
  Do Until 2 ^ StopPoint >= ElemCnt ‘work out the maximum number of elements
      StopPoint = StopPoint |PLS| 1        ‘that need to be read to find the value
  Loop
  StopPoint = StopPoint |PLS| 1
  LowPoint = LBound(BCArray())
  HighPoint = UBound(BCArray())
  ChopPoint = ((HighPoint - LowPoint) / 2) |PLS| LowPoint
  Check1 = Right$(String$(10, “0”) & UCase$(SearchValue), 10)
  ‘We may have to deal with the problem of variable character counts so it can be a
  ‘good idea to pad the strings with leading characters of a low ASCII value
  ‘Plus this search is case insensitive - hence the UCase$() function
  ‘If you need case sensitivity - take it out
  Check2 = Trim$(BCArray(ChopPoint).keyvalue)
  Check2 = Right$(String$(10, “0”) & Ucase$(Check2), 10)
  Do Until Check1 = Check2 Or ChopCount >= StopPoint
      If Check2 < Check1 Then
          LowPoint = ChopPoint
      Else
          HighPoint = ChopPoint
      End If
      ChopCount = ChopCount |PLS| 1
      ChopPoint = (HighPoint - LowPoint) / 2 |PLS| LowPoint
      Check2 = Trim$(BCArray(ChopPoint).keyvalue)
      Check2 = Right$(String$(10, “0”) & Ucase$(Check2), 10)
  Loop
  If Check1 = Check2 then
      BinaryChop = ChopPoint
  Else
      BinaryChop = ValueNotFound
  End If
End Function

[RhinoBanga]

Excellent ... now you just have to adapt it to reading a LVW.

[KingSparta]

Thats What I Was Thinking....

In the Mean Time I Created A Program Using The Listview, Filled The DataGrid, And Using The Finditem Command You Can Search And Once It Finds It, Selects Item, And I Can Have It Fill Four Text Boxes (SongName, Artist Name, Year, And Chart Position) With What Was Found.

So It Is Possable To Use It (Maybe)

Not Sure What One Would Be Faster, Maybe I Can Figure That Out Later.

At Any Rate I Will Play With Both

Like I Said, Thanks For The Help


UPDATE:

I Think I Will Be Using The FindItem Command, It Will Search To The End Of A 20000 Line Database In Less Than A 1\2 Second (I Could Not Start The Stop Watch And It Was Done).

[RhinoBanga]

Be carefull though dude ... it may take 1/2 a second on your computer ... what about those with slower ones?

At least with sorting/binary chop you can guarantee a sub-second response time.