Describe the bug I think there is an error in the gunique and als

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Wrong number of groups about stata-gtools HOT 1 OPEN

m-elholm commented on July 21, 2024

Wrong number of groups

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Comments (1)

mcaceresb commented on July 21, 2024

@m-elholm I think the more likely explanation is that you've run into the limits of 4-byte floats (see the generating IDs section here). This snippet shows that gunique is working correctly, and that x is indeed the problem, which has repeated values:

. clear

. set obs 35000000
Number of observations (_N) was 0, now 35,000,000.

. gen x = _n

. gen long y = _n

. gen double z = _n

. gunique x
N = 35,000,000; 25,527,216 unbalanced groups of sizes 1 to 5

. gunique y
N = 35,000,000; 35,000,000 balanced groups of size 1

. gunique z
N = 35,000,000; 35,000,000 balanced groups of size 1


. format %21.0fc x y z

. l in `=_N-4'/l

          +--------------------------------------+
          |          x            y            z |
          |--------------------------------------|
34999996. | 34,999,996   34,999,996   34,999,996 |
34999997. | 34,999,996   34,999,997   34,999,997 |
34999998. | 35,000,000   34,999,998   34,999,998 |
34999999. | 35,000,000   34,999,999   34,999,999 |
35000000. | 35,000,000   35,000,000   35,000,000 |
          +--------------------------------------+

One solution is to type such data `c(obs_t)', which contains the smallest data type that can store _n (and will change as the number of observations in your data changes).

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