Is there a way to specify a number of vlookup results?

Question

I'm trying to make a kind of loose pivot-table-like date record lookup. Probably best if I show something analogous to what I'm wanting:
Table1
Date
BookRead
1/1/13
Les Miserables
1/2/13
The Hunchback of Notre Dame
1/3/13
Les Miserables
1/4/13
The Phantom of the Opera
1/5/13
Don Quixote
1/6/13
The Hunchback of Notre Dame
1/7/13
War and Peace
1/8/13
Les Miserables
1/9/13
Les Miserables
1/10/13
The Phantom of the Opera
1/11/13
Les Miserables
1/12/13
Don Quixote
1/14/13
The Hunchback of Notre Dame
1/15/13
Les Miserables
In a separate table, I want to be able to pull the data this way, from most recent (Date1) to least (Date4):
Table2
BookRead
Date1
Date2
Date3
Date4
Don Quixote
1/12/13
1/5/13
Les Miserables
1/15/13
1/11/13
1/9/13
1/8/13
The Hunchback of Notre Dame
1/14/13
1/6/13
1/2/13
The Phantom of the Opera
1/10/13
1/4/13
War and Peace
1/7/13
The results in each row need to be the most recent four instances for that book(e.g., "Les Miserables" should only return the last four instances and disregard any more) and only the results for that book.
I've been trying to rack my brain on how to dynamically limit the range of rows for a VLOOKUP: that is, in each row of Table2:
- Date1: VLOOKUP for last instance as usual (which will return the bottom-most result)
- Date2: VLOOKUP for last instance prior to the row found in Date1
- Date3: VLOOKUP for last instance prior to the row found in Date2
- Date4: VLOOKUP for last instance prior to the row found in Date3
I've already tried category tables; it doesn't come close to what I want. Heck, VLOOKUP may not even be the way to go.
I'm concerned this will create an ENORMOUS amount of calculations, as the lookup table (Table2) I need to add this feature to currently has over 2700 rows, and the source table (Table1) it will compute from has over 1400. (That's right, I will be testing a TON of items in the first table that will have no instance at all in the second--that is, I want to test for way more "books" than are even used in the record. I know this seems backwards, but humor me.)
Is this doable, or am I delusional?

Answer 1

Hello
Here's something you may try. Not sure at all, though, whether this works acceptably fast for thousands of entries.
Table 2 will retieve unique book titles from Table 1 by using row indices in Table 1 :: E. If you're using independent table with unique book titles to retrieve data from Table 1, Table 1 :: E is not necessary and you can simply replace the formulae in Table 2 :: A with the unique book titles.
Table 1 works as follows.
1) In column C, count the occurence of each book title in column B after the current date in column A.
2) In column D, build string TITLE[k], where TITLE = title in column A, k = number of occurence in column C.
3) In column E, retrive the row indices where k = 1 in column C (i.e., row indices of most recently read books).
Table 2 works as follows.
1) In column A, retrieve the (unique) book titles in rows whose indices are listed in Table 1 :: E.
2) In column B, retiieve date in Table 1 :: A for TITLE[1] in Table 1 :: D, where TITLE = title in column A.
3) In column C, retiieve date in Table 1 :: A for TITLE[2] in Table 1 :: D, where TITLE = title in column A.
4) In column D, retiieve date in Table 1 :: A for TITLE[3] in Table 1 :: D, where TITLE = title in column A.
5) In column E, retiieve date in Table 1 :: A for TITLE[4] in Table 1 :: D, where TITLE = title in column A.
# Table 1
A1  Date
A2  2013-01-01
A3  2013-02-01
A4  2013-03-01
A5  2013-04-01
A6  2013-05-01
A7  2013-06-01
A8  2013-07-01
A9  2013-08-01
A10 2013-09-01
A11 2013-10-01
A12 2013-11-01
A13 2013-12-01
A14 2013-12-02
A15 2013-12-03
B1  BookRead
B2  Les Miserables
B3  The Hunchback of Notre Dame
B4  Les Miserables
B5  The Phantom of the Opera
B6  Don Quixote
B7  The Hunchback of Notre Dame
B8  War and Peace
B9  Les Miserables
B10 Les Miserables
B11 The Phantom of the Opera
B12 Les Miserables
B13 Don Quixote
B14 The Hunchback of Notre Dame
B15 Les Miserables
C1  k
C2  =COUNTIF(OFFSET($B$1,ROW($B2)-1,0,ROWS($B)-ROW($B2)+1,1),$B2)
C3  =COUNTIF(OFFSET($B$1,ROW($B3)-1,0,ROWS($B)-ROW($B3)+1,1),$B3)
C4  =COUNTIF(OFFSET($B$1,ROW($B4)-1,0,ROWS($B)-ROW($B4)+1,1),$B4)
C5  =COUNTIF(OFFSET($B$1,ROW($B5)-1,0,ROWS($B)-ROW($B5)+1,1),$B5)
C6  =COUNTIF(OFFSET($B$1,ROW($B6)-1,0,ROWS($B)-ROW($B6)+1,1),$B6)
C7  =COUNTIF(OFFSET($B$1,ROW($B7)-1,0,ROWS($B)-ROW($B7)+1,1),$B7)
C8  =COUNTIF(OFFSET($B$1,ROW($B8)-1,0,ROWS($B)-ROW($B8)+1,1),$B8)
C9  =COUNTIF(OFFSET($B$1,ROW($B9)-1,0,ROWS($B)-ROW($B9)+1,1),$B9)
C10 =COUNTIF(OFFSET($B$1,ROW($B10)-1,0,ROWS($B)-ROW($B10)+1,1),$B10)
C11 =COUNTIF(OFFSET($B$1,ROW($B11)-1,0,ROWS($B)-ROW($B11)+1,1),$B11)
C12 =COUNTIF(OFFSET($B$1,ROW($B12)-1,0,ROWS($B)-ROW($B12)+1,1),$B12)
C13 =COUNTIF(OFFSET($B$1,ROW($B13)-1,0,ROWS($B)-ROW($B13)+1,1),$B13)
C14 =COUNTIF(OFFSET($B$1,ROW($B14)-1,0,ROWS($B)-ROW($B14)+1,1),$B14)
C15 =COUNTIF(OFFSET($B$1,ROW($B15)-1,0,ROWS($B)-ROW($B15)+1,1),$B15)
D1  book[k]
D2  =B2&"["&C2&"]"
D3  =B3&"["&C3&"]"
D4  =B4&"["&C4&"]"
D5  =B5&"["&C5&"]"
D6  =B6&"["&C6&"]"
D7  =B7&"["&C7&"]"
D8  =B8&"["&C8&"]"
D9  =B9&"["&C9&"]"
D10 =B10&"["&C10&"]"
D11 =B11&"["&C11&"]"
D12 =B12&"["&C12&"]"
D13 =B13&"["&C13&"]"
D14 =B14&"["&C14&"]"
D15 =B15&"["&C15&"]"
E1  i[k=1]
E2  =MATCH(1,$C,0)
E3  =IFERROR(E2+MATCH(1,OFFSET($C$1,E2,0,ROWS($C)-E2,1),0),"")
E4  =IFERROR(E3+MATCH(1,OFFSET($C$1,E3,0,ROWS($C)-E3,1),0),"")
E5  =IFERROR(E4+MATCH(1,OFFSET($C$1,E4,0,ROWS($C)-E4,1),0),"")
E6  =IFERROR(E5+MATCH(1,OFFSET($C$1,E5,0,ROWS($C)-E5,1),0),"")
E7  =IFERROR(E6+MATCH(1,OFFSET($C$1,E6,0,ROWS($C)-E6,1),0),"")
E8  =IFERROR(E7+MATCH(1,OFFSET($C$1,E7,0,ROWS($C)-E7,1),0),"")
E9  =IFERROR(E8+MATCH(1,OFFSET($C$1,E8,0,ROWS($C)-E8,1),0),"")
E10 =IFERROR(E9+MATCH(1,OFFSET($C$1,E9,0,ROWS($C)-E9,1),0),"")
E11 =IFERROR(E10+MATCH(1,OFFSET($C$1,E10,0,ROWS($C)-E10,1),0),"")
E12 =IFERROR(E11+MATCH(1,OFFSET($C$1,E11,0,ROWS($C)-E11,1),0),"")
E13 =IFERROR(E12+MATCH(1,OFFSET($C$1,E12,0,ROWS($C)-E12,1),0),"")
E14 =IFERROR(E13+MATCH(1,OFFSET($C$1,E13,0,ROWS($C)-E13,1),0),"")
E15 =IFERROR(E14+MATCH(1,OFFSET($C$1,E14,0,ROWS($C)-E14,1),0),"")
# Table 2
A1  book
A2  =IFERROR(INDEX(Table 1::$B,Table 1::E2,1),"")
A3  =IFERROR(INDEX(Table 1::$B,Table 1::E3,1),"")
A4  =IFERROR(INDEX(Table 1::$B,Table 1::E4,1),"")
A5  =IFERROR(INDEX(Table 1::$B,Table 1::E5,1),"")
A6  =IFERROR(INDEX(Table 1::$B,Table 1::E6,1),"")
A7  =IFERROR(INDEX(Table 1::$B,Table 1::E7,1),"")
A8  =IFERROR(INDEX(Table 1::$B,Table 1::E8,1),"")
A9  =IFERROR(INDEX(Table 1::$B,Table 1::E9,1),"")
B1  date[i[k=1]]
B2  =IFERROR(INDEX(Table 1::$A,MATCH($A2&"[1]",Table 1::$D,0),0),"")
B3  =IFERROR(INDEX(Table 1::$A,MATCH($A3&"[1]",Table 1::$D,0),0),"")
B4  =IFERROR(INDEX(Table 1::$A,MATCH($A4&"[1]",Table 1::$D,0),0),"")
B5  =IFERROR(INDEX(Table 1::$A,MATCH($A5&"[1]",Table 1::$D,0) ,0) ,"")
B6  =IFERROR(INDEX(Table 1::$A,MATCH($A6&"[1]",Table 1::$D,0) ,0) ,"")
B7  =IFERROR(INDEX(Table 1::$A,MATCH($A7&"[1]",Table 1::$D,0) ,0) ,"")
B8  =IFERROR(INDEX(Table 1::$A,MATCH($A8&"[1]",Table 1::$D,0) ,0) ,"")
B9  =IFERROR(INDEX(Table 1::$A,MATCH($A9&"[1]",Table 1::$D,0) ,0) ,"")
C1  date[i[k=2]]
C2  =IFERROR(INDEX(Table 1::$A,MATCH($A2&"[2]",Table 1::$D,0),0),"")
C3  =IFERROR(INDEX(Table 1::$A,MATCH($A3&"[2]",Table 1::$D,0),0),"")
C4  =IFERROR(INDEX(Table 1::$A,MATCH($A4&"[2]",Table 1::$D,0),0),"")
C5  =IFERROR(INDEX(Table 1::$A,MATCH($A5&"[2]",Table 1::$D,0),0),"")
C6  =IFERROR(INDEX(Table 1::$A,MATCH($A6&"[2]",Table 1::$D,0) ,0) ,"")
C7  =IFERROR(INDEX(Table 1::$A,MATCH($A7&"[2]",Table 1::$D,0) ,0) ,"")
C8  =IFERROR(INDEX(Table 1::$A,MATCH($A8&"[2]",Table 1::$D,0) ,0) ,"")
C9  =IFERROR(INDEX(Table 1::$A,MATCH($A9&"[2]",Table 1::$D,0) ,0) ,"")
D1  date[i[k=3]]
D2  =IFERROR(INDEX(Table 1::$A,MATCH($A2&"[3]",Table 1::$D,0),0),"")
D3  =IFERROR(INDEX(Table 1::$A,MATCH($A3&"[3]",Table 1::$D,0),0),"")
D4  =IFERROR(INDEX(Table 1::$A,MATCH($A4&"[3]",Table 1::$D,0),0),"")
D5  =IFERROR(INDEX(Table 1::$A,MATCH($A5&"[3]",Table 1::$D,0) ,0) ,"")
D6  =IFERROR(INDEX(Table 1::$A,MATCH($A6&"[3]",Table 1::$D,0) ,0) ,"")
D7  =IFERROR(INDEX(Table 1::$A,MATCH($A7&"[3]",Table 1::$D,0) ,0) ,"")
D8  =IFERROR(INDEX(Table 1::$A,MATCH($A8&"[3]",Table 1::$D,0) ,0) ,"")
D9  =IFERROR(INDEX(Table 1::$A,MATCH($A9&"[3]",Table 1::$D,0) ,0) ,"")
E1  date[i[k=4]]
E2  =IFERROR(INDEX(Table 1::$A,MATCH($A2&"[4]",Table 1::$D,0),0),"")
E3  =IFERROR(INDEX(Table 1::$A,MATCH($A3&"[4]",Table 1::$D,0) ,0) ,"")
E4  =IFERROR(INDEX(Table 1::$A,MATCH($A4&"[4]",Table 1::$D,0),0),"")
E5  =IFERROR(INDEX(Table 1::$A,MATCH($A5&"[4]",Table 1::$D,0) ,0) ,"")
E6  =IFERROR(INDEX(Table 1::$A,MATCH($A6&"[4]",Table 1::$D,0) ,0) ,"")
E7  =IFERROR(INDEX(Table 1::$A,MATCH($A7&"[4]",Table 1::$D,0) ,0) ,"")
E8  =IFERROR(INDEX(Table 1::$A,MATCH($A8&"[4]",Table 1::$D,0) ,0) ,"")
E9  =IFERROR(INDEX(Table 1::$A,MATCH($A9&"[4]",Table 1::$D,0) ,0) ,"")
Hope this may help,
H