[Gretl-users] Re: series indexing
On Fri, 11 Sep 2020, Riccardo (Jack) Lucchetti wrote:
A user wrote me in private, asking me about some oddities on series
indexing
via strings. I put together a little example:
<hansl>
nulldata 4
xs = normal(2,1)
setobs 1 2000 --time-series
# 1: this works
xs["2000"] = 3
# 2: this works too
a = sprintf("\"2000\"")
xs[@a] = 33
# 3: this doesn't
a = "2000"
xs[a] = 33
</hansl>
if assignments 1 and 2 work, one sees no reason why 3 shouldn't work too. Or
ami I missing something obvious?
Well, when indexing into a series gretl expects one of the
following:
* a literal observation-marker string
* an integer (1-based) observation number
* an expression which evaluates to an observation number
That's fairly flexible. But if we get a variable as an index we try
to interpret it as a plain integer, which obviously doesn't work for
a = "2000". Note that these work:
a = 1
xs[a] = 33
and
xs[obsnum(2000)] = 33
Allin