Extracting Unique, Duplicate and Missing Items using Formulas [spreadcheats]

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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:

  1. Using Advanced Data Filter
  2. Using countif() and auto filter
  3. 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:

  1. Using countif() and then auto-filter
  2. 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.

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12 Responses to “Analyzing Search Keywords using Excel : Array Formulas in Real Life”

  1. Very interesting Chandoo, as always. Personally I find endless uses for formulae such as {=sum(if(B$2:B$5=$A2,$C$2$C$5))}, just the flexibility in absolute and relative relative referencing and multiple conditions gives it the edge over dsum and others methods.

    I've added to my blog a piece on SQL in VBA that I think might be of interest to you http://aviatormonkey.wordpress.com/2009/02/10/lesson-one-sql-in-vba/ . It's a bit techie, but I think you might like it.

    Keep up the good work, aviatormonkey

  2. Andy Pope says:

    Hi Chandoo,

    You might find this coded solution I posted on a forum interesting.

    http://www.excelforum.com/excel-programming/680810-create-tag-cloud-in-vba-possible.html

  3. [...] under certain circumstances.  One of the tips involved arranging search keywords in excel using Array Forumlas.  Basically, if you need to know how frequent a word or group of keywords appear, you can use this [...]

  4. Chandoo says:

    @Aviatormonkey: Thanks for sharing the url. I found it a bit technical.. but very interesting.

    @Andy: Looks like Jarad, the person who emailed me this problem has posted the same in excelforum too. Very good solution btw...

  5. bob says:

    Realy great article

    "You can take this basic model and extend it to include parameters like number of searches each key phrase has, how long the users stay on the site etc. to enhance the way tag cloud is generated and colored."

    How would you go about doing this? I think it would need some VB

  6. Thiago says:

    Hi,
    I found the usage very interesting, but is giving me hard time because the LENs formula that use ranges are not considering the full range, in other words, the LEN formula is only bringing results from the respective "line" cell.

    Using the example, when I place the formula to calculate the frequency for "windows" brings me only 1 result, not 11 as displayed in the example. It seems that the LEN formula using ranges is considering the respective line within the range, not the full range.

    Any hint?

  7. Hui... says:

    @Thiago
    You have to enter the formula as an Array Formula
    Enter the Formula and press Ctrl+Shift+Enter
    Not just Enter

  8. Gary says:

    is there a limit to the number of lines it can analyse.
    Ie i am trying to get this to work on a list of sentances 1500 long. 

    • Hui... says:

      @Gary
      In Excel 2010/2013 Excel is only limited by available memory,
      So just give it a go
      As always try on a copy of the file first if you have any doubts

  9. Sumit says:

    Apologies if I am missing something, but coudn't getting frequency be easier with Countif formula. Something like this - COUNTIF(Range with text,"*"&_cell with keyword_&"*")

  10. Ray says:

    Apologies if I missed, but what is the Array Formula to:

    1. Analyze a list of URL's or a list of word phrases to understand frequency;
    2. List in a nearby column from most used words to least used words;
    3. Next to the list of words the count of occurrences.

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