-sxpose- is a user-written command on SSC. (You are
asked to say where non-official programs you use come from.)
I guess wildly that this segment is part of some larger
dataset with some identifier, say -id-, labelling distinct
groups (panels).
Under that assumption, you can proceed in various ways.
Here is one I like a lot
bysort id (firsttag) : gen first = value[1]
bysort id (maxtag) : gen max = value[1]
bysort id (mintag) : gen min = value[1]
bysort id (lasttag) : gen last = value[1]
by id: keep if _n == 1
Consider the first statement. Within blocks
defined by -id-, sort the observation with
smallest value of -firsttag- to the front.
Then use its -value-.
The rest is just the same trick again and again,
plus clean-up: after that we can keep just one observation
from each group.
Here is another way to do the same thing:
foreach x in first max min last {
bysort id (`x'tag) : gen `x' = value[1]
}
by id: keep if _n == 1
And another rather different way:
foreach x in first max min last {
egen `x' = mean(value * `x'tag), by(id)
}
bysort id : keep if _n == 1
Nick
[email protected]
Thomas Speidel
I have a dataset that looks like this:
date value maxtag mintag firsttag lasttag
Jan 2001 13.616 1 . 1 .
Oct 2001 2.632 . 1 . .
Jul 2007 6.474 . . . 1
*tag indicates whether a particular value was the first, last, min or
max. Obviously, the possibility of ties exist. In this case 13.616 is
both the max and first value.
What I am trying to get at is single observation dataset that looks like
this:
firsttag mintag maxtag lasttag
13.616 2.632 13.616 6.474
I have been able to do so when no ties are present (using sxpose after
some data management). However, when ties are present I need to be able
to perhaps add one or two more observations to the initial dataset to
reflect the presence of ties (in this case I would need to add onother
row for Jan 2001 and change the max and firsttag accordingly so that
only one tag exists for each row). Perhaps someone has a better suggestion.
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