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Swap key-value in dictionary
hi, how can I swap key and list of values using q? Thanks!
python version: https://stackoverflow.com/questions/51740270/python-dictionary-swap-keyvalue-pair-when-values-exist-in-mutiple-keys
for example:
1 2 3!(4 5 3;6 7 3;4 1)
becomes
1 3 4 5 6 7!(enlist 3;1 2;1 3;enlist 1;enlist 2;enlist 2)
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3 Replies
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This achieves what you’re looking for.
q)d:1 2 3!(4 5 3;6 7 3;4 1)
q)r:1 3 4 5 6 7!(enlist 3;1 2;1 3;enlist 1;enlist 2;enlist 2)
q){a!key[x]where each flip value(a:asc distinct raze x)in/:x} d 1| ,3 3| 1 2 4| 1 3 5| ,1 6| ,2 7| ,2
q)r~{a!key[x]where each flip value(a:asc distinct raze x)in/:x}d 1b -
Another method:
q){a!x a:asc key x:group(!). flip raze key[x],''value x}d 1| ,3 3| 1 2 4| 1 3 5| ,1 6| ,2 7| ,2 -
{key[x][i]!get[x]i:iasc key x:group(!). flip raze key[x],''get x}indexing into the keys instead of doing a lookup a smidge faster
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