Rule - referencing the prior year

[chewza]

Hi there

In my rule, I am trying to access the previous year.
Was hoping that something like '.......!Year-1....' would work, but no luck!

I know that I could use attributes to achieve this, whereby I can specify a prior year attribute for each dimension element, and reference this, but is there no way to achieve this using the method I am attempting above..??

Regards
Chris

[Michel Zijlema]

Hi Chris,

The !Year parameter refers to an elementname in a dimension, which is a string value.
If you want to make the rule work this way you need to convert to number, subtract 1 and convert back to string. The correct notation would be: Str(Value(!Year)-1, 4, 0).

Michel

[Michel Zijlema]

The correct notation would be: Str(Value(!Year)-1, 4, 0).

Oops, this is not PALO...
The correct notation would be Str(Numbr(!Year)-1, 4, 0).

Michel

[lotsaram]

The correct notation would be Str(Numbr(!Year)-1, 4, 0)

This assumes that the year dimension is in a yyyy format. This is not always going to be the case, where financial years and calendar years are not the same the format for the year dimension can often be something like "10-11" or "FY11" in which case this is not going to work. In that case you need something else. For reasons known only to the original developers TM1 has a DNEXT element information function but no equivalent "DPREV" function, you would therefore need to combine DIMIX and DIMNM, for example:
DIMNM('Year', DIMIX('Year', !Year) - 1);
However in my opinion it is never a good idea to make rules dependent on dimension structure or indexing as this could easily change and have many unwelcome consequences, it is always better to base these kinds of time calculations on either attributes or lookup cubes, for example:
AttrS('Year', !Year, 'Prev Year');

[chewza]

Brilliant - thanks guys! Very helpful