Set expression being ignored

[#1]

I have a list of items with prices in different currencies, each item in a class which is used as the dimension.  I want to display the totals by class in a selected display currency.  And I want to do this with (A) the current selection {$}, and (B) the entire set {1}.

The load statements are as follows:

Data:

LOAD * INLINE [

    Class,Item,Price,Currency

    'Tech','TV',200,'GBP'

    'Tech','VCR',100,'EUR'

    'Tech','Speakers',400,'USD'

    'Home','Sofa',800,'GBP'

    'Home','Table',900,'EUR'

    'Home','Rug',200,'USD'

    'Garden','Swing',150,'GBP'

    'Garden','Parasol',250,'GBP'

    'Garden','Mower',300,'GBP'

];

Currencies:

LOAD * INLINE [

    Currency,ExchangeRate

    USD, 1.00

    EUR, 0.90

    GBP, 0.65

];

DisplayCurrencies:

LOAD * INLINE [

    DisplayCurrency,DisplayRate

    USD, 1.00

    EUR, 0.90

    GBP, 0.65

];

My expressions are respectively:

(A):     DisplayRate*Sum(Price/ExchangeRate)

(B):     DisplayRate*Sum({1}Price/ExchangeRate)

When I select different combinations of Class the first chart behaves as expected, displaying the selected dimensions.

But the second chart changes in synch with the first whereas I expect it to show all dimensions all the time.

If I remove the scalar DisplayRate from the second expression to become

Sum({1}Price/ExchangeRate)

then it displays all classes all the time, as I expect.

Is there some subtlety in set expressions that I have missed?

I am attaching my QVW file.

[Gysbert_Wassenaar]

DisplayRate is also aggregated using the implicit Only() function since you didn't specify an aggregation function explicitly. Your expression is really Only(DisplayRate)*Sum(Price/ExchangeRate). To make that ignore selections as well you need to add the record set definition {1} to the Only() function too: Only({1}DisplayRate)*Sum({1}Price/ExchangeRate)

[#3]

Try this expression

=sum({1} {<DisplayRate,Class>} DisplayRate*Price/ExchangeRate)

[#4]

I don't understand the syntax of the inner {..}.

What I did try was

$(=DisplayRate)*Sum({1}Price/ExchangeRate)

and this worked.

So now I want to understand how dollar-sign expansions affect the logic.

[#5]

This gives "no data to display"!  But surely since there is only one value selected, Only() should be identical whatever the set identifier?

[Gysbert_Wassenaar]

Can you post a small qlikview document that demonstrates the problem?

[#7]

It's attached to the initial entry.

[swuehl]

Kind of strange.

I got it working using a variable vRate = DisplayRate

[#9]

Of course this is a contrived example to illustrate a difficulty I have found on a bigger data set.  So I am interested in the principles of what works and why.

What is the avg() function doing that is different from just using a single-valued field?  In another post to this thread I tried $(=DisplayRate) and this worked.  I can use a constant scalar such as 0.5*Sum(...) so what type of entity can I use instead of the 0.5?

[Gysbert_Wassenaar]

Yeah, I can understand why only({1}DisplayRate)*... wouldn't work. But only({<Class>}DisplayRate)*... should afaik. Perhaps the fact that the tables are not linked is causing the weirdness. As soon as I outer join DisplayCurrencies with the Currencies table the weirdness is gone. Of course the expression results are bogus after the outer join (though sum(distinct...) works). My conclusion: use data islands with care. They're inhabited by gremlins.