Today I have learned this very cool way to find if a list has duplicate items or not.
This technique uses array formulas (do not shudder, believe me they are not as difficult as you may think)
First the formula
Assuming your list is in the range, C3: C9, the array formula to find if a list has duplicate items or not is,
=IF(MAX(COUNTIF(C$3:C$9;C3:C9))>1,"list is not unique","list is unique")
Now the explanation
How do you know if a list has no duplicates? Simple, we find the number of times each item has appeared in the list and see if any of those counts are more than 1.
Now, take a look at the formula. It says find the maximum of individual item counts using countif (learn excel countif function) and if the maximum is more than 1, then the list has duplicates, otherwise it is unique.
But…
Yes, entering the formula will not work by itself. You have to make it array formula.
How do you do that?
Oh, that is simple, you just take the excel spreadsheet and whack it until it turns blue.
well, not really. all you need to do is enter the formula and press CTRL + SHIFT ENTER instead of just pressing enter.
that way excel converts your formula to array formula and the COUNTIF(C$3:C$9,C3:C9) will return an array of counts instead of one value. Now you can also guess why we have absolute reference for one parameter of countif () and relative reference for another. Learn more about Absolute and Relative References in excel formulas.
More on Finding and Removing Duplicate Items
> Using pivot tables to get unique items in excel
> Getting unique items using data filter and formulas
> Use advanced data filters to find unique items
> Eliminate Duplicate Entries in a List using Formulas
> Get Unique items using Excel 2007 built in features
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2 Responses to “Top 10 Power BI Interview Questions & Answers”
Hello...
In Power BI I have data that includes months by name only (e.g. May, April, December...)
I need to build charts etc. but i need the months to go chronologically... not alphabetically... I cannot seem to find the fix to this.... once again, my data does NOT have an actual date attached to it (like 02/01/2023)....only month names... can i use a helper table wher i id the month names as numbers 1 thru 12? and if so, how do i manage this to work for me ?
Thank you.
~Keith
You need to setup an extra table to map each month name to a running number. A simple 12 row table like
Jan 1
Feb 2
Mar 3
..
Dec 12
Then create a relationship between this month table and your month column
Now, go to "table view" in Power BI and set the sort by column to month number for the month name column on this new table.
Finally, use the new table's month name whenever you need to refer to the month name in the visuals.
They will be chronologically arranged.