Create a list of duplicates where adjacent cell value meets a condition
Question: How do I filter duplicates with a condition?
Answer:
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:
If you want duplicates sorted from A to Z, read this article:
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 […]
Extract a list of alphabetically sorted duplicates from a column
Learn how to filter duplicates:
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 […]
Extract a list of duplicates from a column
You can also use more than one condition, this article shows you how:
Filter duplicate values using critera
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Filter a unique distinct list:
5 easy ways to extract Unique Distinct Values
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5 easy ways to extract Unique Distinct Values
Explaining formula in cell E4
Step 1 - Identify values that has not been displayed before
COUNTIF($E$3:E3, $C$3:$C$9)=0
becomes
COUNTIF("Duplicate items",{"AA";"BB";"AA";"CC";"AA";"CC";"BB"})=0
and returns
{TRUE;TRUE;TRUE;TRUE;TRUE;TRUE;TRUE}
In cell E4 no values has been shown before so the array returns TRUE for all values.
How to use the COUNTIF function
Counts the number of cells that meet a specific condition.
How to use the COUNTIF function
Step 2 - Find duplicates in category 2
COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1
becomes
COUNTIFS({2;2; 1;2;1; 2;2}, 2, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"}, {"AA";"BB";"AA";"CC";"AA";"CC";"BB"})>1
becomes
{1;2;1;2;1;2;2}>1
and returns {FALSE;TRUE; FALSE;TRUE;FALSE; TRUE;TRUE}
How to use the COUNTIFS function
Checks multiple conditions against the same number of cell ranges and counts how many times all criteria are met.
How to use the COUNTIFS function
Step 3 - Multiply arrays
(COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1)
becomes
{TRUE;TRUE;TRUE;TRUE;TRUE;TRUE;TRUE} * {FALSE;TRUE; FALSE;TRUE;FALSE; TRUE;TRUE}
and returns {0;1; 0;1;0; 1;1}
Step 4 - Divide 1 with array
1/(((COUNTIF($E$3:E3, $C$3:$C$9)=0)*(COUNTIFS($B$3:$B$9, $F$2, $C$3:$C$9, $C$3:$C$9)>1)))
becomes
1/{0;1; 0;1;0; 1;1}
and returns {#DIV/0!; 1;#DIV/0!; 1;#DIV/0!; 1;1}
Step 5 - Find last matching value in array
The LOOKUP function ignores errors but requires the second argument to be sorted ascending. However our list contains only errors or 1 so the LOOKUP function returns the last matching 1 in the array.
LOOKUP(2, 1/(((COUNTIF($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.
How to use the LOOKUP function
Finds a value in a sorted cell range and returns a value on the same row.
How to use the LOOKUP function
Step 6 - Relative cell refences
The following cell reference is both an absolute and relative cell reference: $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.
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 […]
How to use absolute and relative references
Download excel example file
Filter duplicates with a condition.xlsx
(Excel Workbook *.xlsx)
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