Count duplicates and display order of occurence

问题

I am attempting to count the number of occurrences of each value within a column and then output the order in which it was found (top to bottom) with unsorted data. I have been unable to find a suitable formula to accomplish this task. Any assistance is greatly appreciated.

Example:

Number     DuplicateIndex
50               1
20               1
30               1
10               1
30               2
40               1
30               3
50               2

回答1:

Try,

=countif(A$2:A2, A2)

, in B2 and fill down.

回答2:

Try, In B2 and fill down

=unique(A2:A9)

In C2 and fill down

=countif(A$2:A9, B2)

来源：https://stackoverflow.com/questions/37426298/count-duplicates-and-display-order-of-occurence