## Assign each person with randomly unique objects as a daily activity

*Article last updated on April 17, 2013*

**Vijay asks: **

I've 30 objects and 10 people, and I need to assign each person with randomly (unique) selected objects as a daily activity. Would you please suggest me on how I can do it using excel formulae?

**Answer:**

The objects are unique within that day. It means that a person can get the same object next day if unlucky. If this is not what you are looking for, let me know.

The array formula in cell C3:C32 returns a random unique value every time you press F9. The objects are in column F. The table does not need to be sorted by date.

**Array formula in cell C3:**

**How to enter an array formula**

- Select cell C3
- Copy/Paste above array formula to formula bar
- Press and hold CTRL + SHIFT
- Press ENTER

### Explaining array formula in cell C3

**Step 1 - Calculate possible objects**

COUNTIFS($C$2:C2, $F$3:$F$32, $A$2:A2,A3)=0

becomes

{0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0}=0

and returns

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

All objects can be randomly selected. If there had been previous object that day they would have been ruled out.

**Step 2 - Calculate row numbers**

(COUNTIFS($C$2:C2, $F$3:$F$32, $A$2:A2,A3)=0)*MATCH(ROW($F$3:$F$32), ROW($F$3:$F$32))

becomes

{TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE; TRUE}*{1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30}

and returns {1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30}

**Step 3 - Return a random number**

RANDBETWEEN(1, 31-COUNTIF($A$2:A3, A3))

becomes

RANDBETWEEN(1, 31-1)

becomes

RANDBETWEEN(1, 30)

**Step 4 - Return the k-th largest number**

LARGE(array, k)

LARGE((COUNTIFS($C$2:C2, $F$3:$F$32, $A$2:A2,A3)=0)*MATCH(ROW($F$3:$F$32), ROW($F$3:$F$32)), RANDBETWEEN(1, 31-COUNTIF($A$2:A3, A3)))

becomes

LARGE({1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30}, RANDBETWEEN(1, 30))

and returns a random row number between 1 and 30.

**Step 5 - Return a value**

=INDEX($F$3:$F$32, LARGE((COUNTIFS($C$2:C2, $F$3:$F$32, $A$2:A2,A3)=0)*MATCH(ROW($F$3:$F$32), ROW($F$3:$F$32)), RANDBETWEEN(1, 31-COUNTIF($A$2:A3, A3))))

becomes

=INDEX($F$3:$F$32, *random_row_number*)

becomes

=INDEX({"A"; "B"; "C"; "D"; "E"; "F"; "G"; "H"; "I"; "J"; "K"; "L"; "M"; "N"; "O"; "P"; "Q"; "R"; "S"; "T"; "U"; "V"; "X"; "Y"; "Z"; "AA"; "BB"; "CC"; "DD"; "EE"}, *random_row_number*)

and returns a random object.

### Download excel *.xlsx file

Assign each person with randomly (unique) selected objects as a daily activity.xlsx

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**Contact Oscar**

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Hi Oscar,

I am trying to do design a random selector similar to this one, the only difference being that the formula I am using selects a random value from a table array using Vlookup.

So far I have a formula of

=VLOOKUP(RANDBETWEEN(1,COUNT($C:$C)),$C$1:$D$10,2,FALSE)

This is cells A1 - A10, there is a numerical place value (and assists with the max value for the randbetween part) in column C, and in column D are the matches. This makes it easy for me to expand/reduce the range quickly and works reasonably well. However, how can I add a condition to make it return a unique value instead of just any, (so that all ten values are alloted) whilst keeping the ease of expansion as the number of matches and returns may differ considerably, but is always at least a 1:1 ratio.

Thanks,

Chris

Chris G,

Array formula in cell B2:

Download excel *.xlsx file

Random-unique-values.xlsx

Dear Oscar,

Thank you for your efforts. I was looking for the same and came to your post and excel file. I have extended the list as I have a longer list. I'm having an issue that only first value is duplicating whereas the rest it is fine. After keep pressing F9 again and again; the duplicate disappear at time but later again it disappear.

(Screenshot attached)

https://s4.postimg.org/s7is63uu5/Screenshot_2017-08-01_15.52.02.png

can you please help me.