Can you clarify why ALL or ALLEXCEPT is necessary in FILTER?

[UsePowerBI]

Hello

Can you clarify why ALL or ALLEXCEPT is necessary in FILTER?

I see it being used in almost all FILTER statements and I wonder why.

Also, what is their difference in simple terms? The MSDN does not elaborate well.

Thanks!

[PaulDBrown · Accepted solution]

@UsePowerBI 

ALL removes the filters from the table or column specified within. So for example, if you need to calculate the precentage of values in a filter context (a table ot any visual) you will need the total for the denominator in the division. You would then use ALL to calculate the total. It is a very common function 

ALLEXCEPT removes the filters from the table specified except for the column(s) specified within. Typically this is used to calculate the totals of a subset of values. For example, if you have a visual with category and product as the filter context, you would use ALLEXCEPT to obtain the total by category for every row to obtain the percentage of say sales of each product over each  category.

Make sense?

PS. The following article most probably offers a more comprehensible explanatio:

Using ALLEXCEPT vs ALL and VALUES 

[UsePowerBI]

@PaulDBrown  thanks, it makes sense to use it in a Measure which can be filtered with the filters of the Visual/Table, but what about the use of CALCULATE in a Calculated Column? There is no filtering there, right?