Formula to return the previous sequential number from a group

c_fink

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Joined
Oct 22, 2008
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9
Windows 7, Excel 2007. I need help with a formula to find the next lowest sequential number within a group.

Here's an example data set, which represents transactions by date and category:
  • Col A is a user entered Date which will not be in chronological order (unfortunately a sort is not an option)
  • Col B is a user entered Category
  • Col C is a formula that gives the chronological sort order based on the date
    • The formula in C2:C9 is =COUNT($A$2:$A$9)-(RANK(A2,$A$2:$A$9)+COUNTIF($A$2:A2,A2)-1)+1
  • Col D is a formula to determine if the row is the first chronological transaction within the Category
    • The array formula in D2:D9 is =IF(MIN(IF($B$2:$B$9=B2,$C$2:$C$9))=C2,"Y","")
    • This might not be a necessary column, but can be used as a helper
  • Col E is where I would like a formula to give the next lowest value in Col C for the Category in Col B (the order number in Col C for the previous transaction within the same category).
    • I have entered in the values that the formula should return in Col E in the table below

ABCDE
1DateCategoryOrderFirst Transaction?Previous Transaction
24/1/14A2Y2
35/1/14A64
46/1/14A86
54/1/14B1Y1
65/1/14B51
76/1/14B75
84/5/14C3Y3
94/15/14A42

<tbody>
</tbody>

If the current line is the first transaction of the category, the formula should return the value in Col C for that line (so E2 would equal the value in C2, which is 2).

So the first part of the formula could be straightforward, using the helper column:
=IF(D2="Y",C2,

Here's the tricky part: If it's not the first occurrence of the category, then it should return the value of Col C for previous transaction (or the next lowest number in Col C that is within the same category).


  • E3 would return 4, since the previous transaction for Category A was line 9
    • C3 = 6, and of all the values of Col C for Category A (2, 4, 6, 8), 4 is the next lowest
  • E4 would return 6, since the previous transaction for Category A was line 3
    • C4 = 8, and of all the values of Col C for Category A (2, 4, 6, 8), 6 is the next lowest
  • E5 would return 1, since it is the first transaction in Category B
  • E6 would return 1, since the previous transaction for Category B was line 5
    • C6 = 5, and of all the values of Col C for Catebory B (1, 5, 7), 1 is the next lowest
  • Etc.

I'm thinking I need an array formula to find the minimum value within the category, where that value is less than the value of Col C in the current line. Just not sure how to write that...

Any help would be greatly appreciated!
 

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Yeah, the editor doesn't like that less than sign. Using your hash trick, here's what I had (Excel 2007):

=IF(D2="Y",C2,MAX(IF($B$2:$B$9=B2,IF($C$2:$C$9#C2,$C$2:$C$9,""))))
Where the "#" should be swapped with a "<"

Is this how you would structure it for the earlier version of Excel?

Perfect! Although you don't really need the "" at the end.

Cheers
 
Upvote 0
@Aladin: Thanks for the help! I think your formula would work if the data were chronological. It works up until row 6, which is the first out-of-chronological-order date that's not the first transaction within the group. I tried anchoring the COUNTIF statement on the entire column ($B$2:$B$9 instead of $B$2:B2), but it returned incorrect results. Any thoughts?
...

I don't follow. The formula does not look at the dates...

DateCategoryOrderFirst Transaction?Previous Transaction
4/1/2014A2Y2
5/1/2014A6 4
6/1/2014A8 6
4/1/2014B1Y1
5/1/2014B5 5
6/1/2014B7 7
4/5/2014C3Y3
4/15/2014A4 8

<COLGROUP><COL style="WIDTH: 73pt; mso-width-source: userset; mso-width-alt: 3470" width=98><COL style="WIDTH: 82pt; mso-width-source: userset; mso-width-alt: 3896" width=110><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 119pt; mso-width-source: userset; mso-width-alt: 5660" width=159><COL style="WIDTH: 156pt; mso-width-source: userset; mso-width-alt: 7395" width=208><TBODY>
</TBODY>

E2, control+shift+enter, not just enter, and copy down:

=IF(D2="Y",C2,SMALL(IF($B$2:$B$9=$B2,$C$2:$C$9),COUNTIF($B$2:B2,B2)))

What am I missing?
 
Upvote 0

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