Better, maybe not, but another way, maybe.
(({.e.~ i.@(<./)@{. -.~i.@>:@(>./)@{.)expand </./) |:/:~data
┌─────┬───┬─┬┬─┐
│1 2 3│1 3│1││1│
└─────┴───┴─┴┴─┘
----------------------------------------------------------------------
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