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# modify array formula for one without curly brackets

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Hi,
I have had endless problems with Excel crashing or taking an age to calculate. I have just discovered that
it is due to curly bracketed array formulas. My worksheets often contain in excess of 140,000 rows.
Could someone please help me substitute the below formula to one without brackets even if a helper column is required.

{=STDEV.S(IF(\$A\$2:\$A\$22=A2,\$B\$2:\$B\$22))}

Many thanks
Ian
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Commented:
Try the DSTDEV function, which allows you to set multiple criteria...

=DSTDEV(A1:B22,2,D1:D2)

This assumes the column headers are in row 1. Cells D1:D2 contain the criteria, with D1 listing the Column header in cell A1 and cell D2 having the criteria.

A good tutorial for the function is available here.

BTW, the move away from array formulas may or may not help with the calculation time. The biggest issue you will face is the 140,000 rows of data.
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Commented:
Thanks Wayne, I'll check this out after a sleep.
I was wondering if the AGGREGATE function would work and how to modify that formula I posted.
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The DSTDEV function was created specifically for instances where conditions are required, as is the case here. Anything else will be sub-optimal.
Grand Poobah
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Commented:
You could certainly use a helper column with a simple formula that returns the cell value if column A matches the criterion and "" otherwise, since STDEV.S will ignore non-numeric values in the range.
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I've enclosed an attachment if you could kindly insert the formula you recommend.
Many Thanks

Please place formula in column that displays yellow background
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Commented:
Ian, no file is attached, but the formula Rory is suggesting is...

=IF(A2=A\$2, B2, "")

...and copy down as required. You can then use a non-array formula on that column to calculate the standard deviation...

=STDEV.S(K:K)

...assuming column K is where you placed the above formula.
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Commented:
Ahh, I understand now. As you are calculating the StDev for every row, it looks like you'll need to use the array formula you originally used. A helper column won't help.

Why are you calculating the StDev for every row? Can it not be calculated in a summary Pivot Table as in the attached?
Replace-Array-Formula.xlsx
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I haven't worked with pivot tables and not wanting to go down that route. The Array is not an option. I was hoping helper columns would be a solution but you say not.
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OK, I guess we can calculate the StDev manually. You'll need 2 helper columns though, using these formula...

=POWER(E5-AVERAGEIF(D:D,D5,E:E), 2)
=SQRT(SUMIF(D:D,D5,G:G)/(COUNTIF(D:D,D5)-1))

See attached.
Replace-Array-Formula--1-.xlsx
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Commented:
Ok thanks Wayne, I'll have to look at it tomorrow, need sleep
Ian
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Commented:
Here is what I am trying to achieve (refer to link below)
The only difference is I am trying to copy down 100k+ rows that contain indexed ID's.
In attached sheet I would like to normalise values in column B within their index ranges.
There are a series of steps outlined in the article and I have done the AVERAGE column (C)
I've colour coded index ranges for clarity sake.
Thank you for your continued patience.
Ian