In https://code.google.com/p/droop/wiki/BltFileFormat the developer, showing this example:

4 2
3 1 3 4 0  <-  #third line
4 1 3 2 0
2 4 1 3 0
1 2 0
2 2 4 3 1 0
1 3 4 2 0


The third line means that 3 voters put candidate 1 first, candidate 3 second, candidate 4 third, and no more.

And looking for my vote combination I found that there are N other voters with my same combination but the file is listed as follows:

1 5 4 7 0

Repeating this line as many times as voters made this combination.

My question is: Why is not it listed like this

98 5 4 7 0

Like the BLT-file developer said?

1 Answer 1


It's just easier to produce that way, since it's essentially a dump of the raw votes recorded by the system.

At least in the case of OpenSTV 1.7, the weight is handled internally by just duplicating the ballot N times, so it works out the same way. droop on the other hand does actually keep the multiplier internally, and as far as I can tell makes no effort to deduplicate the lines, so there might be an issue there…but the algorithms look similar enough in their implementation at first pass that I imagine it works out correctly regardless.

The bigger issue is the inclusion of 0 value rankings, as this could trip up parsing of the .blt file with droop or another parser stricter than OpenSTV. Per the page you linked it seems droop doesn't support skipped rankings anyway, but the current method of outputting a 0 instead of a -1 would likely result in incorrect results instead of a parse error.

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