Using strings to name variables

[bobshackleton]

I'm writing a global subroutine to which I have sent, among other things, a GROUP that the subroutine brings in as 'data'. I would like to use the names of the series in the group as strings, and concatenate those strings with other strings to call other series that are not in the group (but have similar names) and do calculations on them. Imagine there are only 2 series in 'data' and they're called SERIESA and SERIESB. My intention with this loop is to calculate

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( @pca(QSERIESA) * SERIESA(-1) / AGGREGATE(-1) ) + ( @pca(QSERIESB) * SERIESB(-1) / AGGREGATE(-1) )

so that I am using the name SERIESA to call QSERIESA as well. I wrote the code this way but it doesn't work; the error message states that Eviews "can not assign string expression to numeric variable...." :

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for !x = 1 TO data.@count SERIES laspq = laspq + (@pca("q"+data.@seriesname(!x)) * data.@seriesname(!x)(-1) / aggregate(-1)) next

I'm probably making several different mistakes all at once but could you please explain what I need to do to differently? Thanks very much for your help.

[EViews Gareth]

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data.@seriesname(!i)

returns a string containing the name of the series. It does not return the series itself. When you write an expression involving a series, you write the actual series, not a string containing the series name. I know that sounds subtle, but essentially what you are doing is:

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@pca("q"+"SERIESA") * "SERIESA"(-1)

where you want to be doing:

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@pca(QSERIESA) * SERIESA(-1)

Note the quotes in the first one around the series name (since it is a string).

There are a couple of ways to fix this. The most general is with the following:

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for !x = 1 TO data.@count %name1 = data.@seriesname(!x) %name2 = "Q" + %name1 SERIES laspq = laspq + (@pca({%name2}) * {%name1}(-1) / aggregate(-1)) next

where I am storing the name of the series in a program variable, %name, and then using { } to de-reference that name (i.e., in very simple terms, remove the quotes).


Note if you had another group with the Q variables in it, you can probably just avoid using the name of the series at all:

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for !x = 1 TO data.@count SERIES laspq = laspq + (@pca(qdata(!x)) * data(!x)(-1) / aggregate(-1)) next

Where you can use group(!i) to refer to the ith series in a group.

[bobshackleton]

This is extremely helpful - thank you very much!