The second condition is equivalently in this problem
!missing(pvalue[_n-1])
Nick
[email protected]
Nick Cox
Each block of observations starts either (a) at the first observation or
(b) with a missing value not equal to the previous value.
A block identifier 1, 2, etc. is thus obtained by
gen block = sum((_n == 1) | ((pvalue != pvalue[_n-1]) &
missing(pvalue)))
Then
sort block pvalue n
and the observations are in the order you desired.
Whether you need to use -n- as well I am not clear.
Note that the first observation is special as pvalue[0] is returned as
missing and so is equal to pvalue[1].
In some ways it would be easier to work with the reversed data set. Then
each block starts with a non-missing value. But I don't think the total
code would be easier.
Related tricks were discussed in excruciating detail within
SJ-7-2 dm0029 . . . . . . . . . . . . . . Speaking Stata: Identifying
spells
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N.
J. Cox
Q2/07 SJ 7(2):249--265 (no
commands)
shows how to handle spells with complete control over
spell specification
Nick
[email protected]
Thomas Speidel
I am trying to create a spreadsheet ready table from within Stata and
need to do some data management in order to go from this:
n pvalue
1 .
2 .
3 .
4 .
5 0.151
6 .
7 .
8 .
9 .
10 0.000
11 .
12 .
13 .
14 .
15 0.146
16 .
17 .
18 .
19 .
20 .
21 0.001
...
To this:
n pvalue
1 0.151
2 .
3 .
4 .
5 .
6 0.000
7 .
8 .
9 .
10 .
11 0.146
12 .
13 .
14 .
15 .
16 0.001
17 .
18 .
19 .
20 .
21 .
...
Notice that the blocks are not constant (some are 5, some are 6 etc.
-this is just a portion of the data-). My difficulty lies in the fact
that there is no natural grouping variable. I tried a mixture of
subscripting and sequence generating commands, but did not get too far.
The crucial part is that I need to place the non-missing pvalue at the
beginning of the block, while right now it is at the end.
*
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*
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
