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Re:st:any easy alternative way when -egen- is not allowed to combine
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re:st:any easy alternative way when -egen- is not allowed to combine
Date
Wed, 22 Dec 2010 13:20:09 +0000
Here are some other ways to do it:
bysort ID (indicator) : gen any_pos = indicator[_N]
bysort ID : egen any_pos = max(indicator > 0)
The key to the latter is realising that -max()- can take an
expression. The expression in this example, indicator > 0, will
evaluate to 1 or 0 as desired.
For more discussion, see -- on the relationship between "any" and
-max()- and "all" and -min()- --
-102 (no commands)
explains the use of the by varlist : construct to tackle
a variety of problems with group structure, ranging from
simple calculations for each of several groups to more
advanced manipulations that use the built-in _n and _N
or
SJ-1-1 pr0003 . . . Speaking Stata: How to repeat yourself without going mad
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox
Q4/01 SJ 1(1):86--97 (no commands)
describes systematic ways of repeating the same or similar
operations
The -egen- method is more easily adaptable to the case in which the
variable in question might be missing.
bysort ID : egen any_pos = max(indicator > 0 & indicator < .)
Amanda Fu
========
I notice some options of -egen- are not allowed to combine with by.
I just wondered if there is any good way to handle these situations.
Let me use an example.
----------------------------------------
ID surveyYear indicator (maximum value is 10)
1 1985 0
1 1986 1
1 1987 2
2 1985 0
2 1986 0
2 1987 0
...............
----------------------------------------
I want to create a variable "new" that takes value 1 if there is at
least one year for a ID's indicator is above 0 and takes the value 0
(like ID 1) is all the years the indicator is 0 (like ID 2).
What I wish to use is as following:
. bysort id: egen new=(indicator), anymatch(1/10)
Is there any simple way to do this? Any comments will be helpful. Thank you!
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