Often I wish Microsoft had spent the effort and time on a data genie (and a set of powerful formulas) that can automate common data cleanup tasks like extracting duplicates, makings lists unique, find missing items, remove spaces etc. Alas, instead they have provided features like clippy which are intrusive to say the least.
So as part of our second installment of spreadcheats we will learn how to tackle few of the most common data processing tasks:
Getting Unique Items from a List of Cells
There are 3 simple ways to do this:
- Using Advanced Data Filter
- Using countif() and auto filter
- Using formulas as described here
Assuming you have data as shown in the picture aside (and wishing you will have customers like those):
- First add a column to the left of the list. Here we will use formulas to fill numbers based on the uniqueness of the cell next to it.
- Essentially our formula should generate numbers in increasing order as long as the corresponding item is unique and not increase the number otherwise.
- So the formula for order column can be like this:
=IF(COUNTIF(list-upto-that-point, current element)=1,previous-order+1, previous-order)
See the example below:
remember, the first cell order is 1. - See how we are using both absolute and relative references to fetch the counts.
- Now add another column to the right of the list, here we will fetch unique items.
- We will use vlookup() to fetch each of the 12 unique items. The formula goes like this:
=VLOOKUP(running number,$B$4:$C$22,2,FALSE)
You can wrap the vlookup() with if() formula to avoid seeing #value errors.
That is all. Using this method you can extract unique items froma list.
Eliminating Doubles from a List
There are 2 ways in which you can find and remove duplicates(doubles) in excel lists with ease:
- Using countif() and then auto-filter
- Using formulas
The process for finding duplicates using formulas is same as that of finding unique items.
Instead of writing COUNTIF(list-upto-that-point, current element)=1, we now write COUNTIF(list-upto-that-point, current element)=2. Also the first element’s count should be changed to zero.
Once done the list should look like what you see on the side.
Finding Missing Items by comparing one list with another:
Even though this might seem like a different challenge, it is infact same as the above techniques. You need to use countif() to compare first list’s elements with second list. How? that is your home work.
Download and see these formulas in action:
Still having some doubts? Download the excel tutorial – unique & duplicate items and learn by poking around.
13 Responses to “Data Validation using an Unsorted column with Duplicate Entries as a Source List”
Pivot Table will involve manual intervention; hence I prefer to use the 'countif remove duplicate trick' along with 'text sorting formula trick; then using the offset with len to name the final range for validation.
if using the pivot table, set the sort to Ascending, so the list in the validation cell comes back alphabetically.
Hui: Brillant neat idea.
Vipul: I am intrigued by what you are saying. Please is it possible to show us how it can be done, because as u said Hui's method requires user intervention.
Thks to PHD and all
K
Table names dont work directly inside Data validation.
You will have to define a name and point it to the table name and then use the name inside validation
Eg MyClient : Refers to :=Table1[Client]
And then in the list validation say = MyClient
Kieranz,
Pls download the sample here http://cid-e98339d969073094.skydrive.live.com/self.aspx/.Public/data-validation-unsorted-list-example.xls
Off course there are many other ways of doing the same and integrating the formulae in multiple columns into one.
Pls refer to column FGHI in that file. Cell G4 is where my validation is.
Vipul:
Many thks, will study it latter.
Rgds
K
[...] to chandoo for the idea of getting unique list using Pivot tables. What we do is that create a pivot table [...]
@Vipul:
Thanks, that was awesome! 🙂
@Playercharlie Happy to hear that 🙂
Great contribution, Hui. Solved a problem of many years!
Thanks to you, A LOT
Hi Hui,
Greeting
hope you are doing well.
I'm interested to send you a private vba excel file which i need to show detail of pivot in new workbook instead of showing in same workbook as new sheet.
Please contact me on muhammed.ye@gmail.com
Best Regards