Author: Oscar Cronquist Article last updated on August 19, 2017

Question: How do I filter duplicates with a condition?

Column B contains category and column C contains Items. Only duplicate Items with adjacent Category number 2 is listed in column E.

AA is in category 2 (row 3) and 1 but exists only once in category 2. It is not a duplicate.

BB is in category 2 and exists twice (row 4 and 9). BB has a duplicate.

CC is in category 2 and has a duplicate (row 6 and 8). CC is a duplicate.

Formula in cell E4:

=LOOKUP(2, 1/(((COUNTIF(\$E\$3:E3, \$C\$3:\$C\$9)=0)*(COUNTIFS(\$B\$3:\$B\$9, \$F\$2, \$C\$3:\$C\$9, \$C\$3:\$C\$9)>1))), \$C\$3:\$C\$9)

Recommended articles

Extract a list of alphabetically sorted duplicates from a column
The following array formula extracts duplicate values sorted from A to Z from cell range B3:B21. Excel array formula in […]

Learn how to filter duplicates:

Recommended articles

Extract a list of duplicates from a column
The array formula in cell C2 extracts duplicate values from column A. Only one duplicate of each value is displayed […]

You can also use more than one condition, this article shows you how:

Recommended articles

Filter duplicate values based on criteria
This article demonstrates formulas and Excel tools that extract duplicates based on three conditions. The first and second condition is […]

Filter a unique distinct list:

Recommended articles

5 easy ways to extract Unique Distinct Values
First, let me explain the difference between unique values and unique distinct values, it is important you know the difference […]

### Explaining formula in cell E4

Step 1 - Identify values that has not been displayed before

COUNTIF(\$E\$3:E3, \$C\$3:\$C\$9)=0

becomes

COUNTIF("Duplicate items",{"AA";"BB";"AA";"CC";"AA";"CC";"BB"})=0

and returns

{TRUE;TRUE;TRUE;TRUE;TRUE;TRUE;TRUE}

In cell E4 no values has been shown before so the array returns TRUE for all values.

Recommended articles

How to use the COUNTIF function
Counts the number of cells that meet a specific condition.

Step 2 - Find duplicates in category 2

COUNTIFS(\$B\$3:\$B\$9, \$F\$2, \$C\$3:\$C\$9, \$C\$3:\$C\$9)>1

becomes

COUNTIFS({2;2; 1;2;1; 2;2}, 2, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"}, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"})>1

becomes

{1;2;1;2;1;2;2}>1

and returnsÂ {FALSE;TRUE; FALSE;TRUE;FALSE; TRUE;TRUE}

Recommended articles

How to use the COUNTIFS function
Checks multiple conditions against the same number of cell ranges and counts how many times all criteria are met.

Step 3 - Multiply arrays

(COUNTIF(\$E\$3:E3, \$C\$3:\$C\$9)=0)*(COUNTIFS(\$B\$3:\$B\$9, \$F\$2, \$C\$3:\$C\$9, \$C\$3:\$C\$9)>1)

becomes

{TRUE;TRUE;TRUE;TRUE;TRUE;TRUE;TRUE} *Â {FALSE;TRUE; FALSE;TRUE;FALSE; TRUE;TRUE}

and returns {0;1; 0;1;0; 1;1}

Step 4 - Divide 1 with array

1/(((COUNTIF(\$E\$3:E3, \$C\$3:\$C\$9)=0)*(COUNTIFS(\$B\$3:\$B\$9, \$F\$2, \$C\$3:\$C\$9, \$C\$3:\$C\$9)>1)))

becomes

1/{0;1; 0;1;0; 1;1}

and returnsÂ {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}

Step 5 - Find last matching value in array

The LOOKUP function ignores errors but requires the second argument to be sorted ascending. However our list contains only errors or 1 so the LOOKUP function returns the last matching 1 in the array.

LOOKUP(2, 1/(((COUNTIF(\$E\$3:E3, \$C\$3:\$C\$9)=0)*(COUNTIFS(\$B\$3:\$B\$9, \$F\$2, \$C\$3:\$C\$9, \$C\$3:\$C\$9)>1))), \$C\$3:\$C\$9)

becomes

LOOKUP(2, {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}, \$C\$3:\$C\$9)

becomes

LOOKUP(2, {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"})

and returns "BB" in cell E4. BB is the corresponding value to the last 1 in the array, bolded above.

Recommended articles

How to use the LOOKUP function
Finds a value in a sorted cell range and returns a value on the same row.

Step 6 - Relative cell refences

The following cell reference is both an absolute and relative cell reference:Â \$E\$3:E3. When you copy the formula to cells below, the cell ref changes. That way the formula knows which values have been displayed before.

Recommended articles

How to use absolute and relative references
What is a reference in Excel? Excel has an A1 reference style meaning columns are named letters A to XFD […]

### Get excel example file

Filter duplicates with a condition.xlsx

(Excel Workbook *.xlsx)