One is itself a collection
ABC
Def
Ghi
B is a collection
LMN
Opq
RST
Want to combine them into a collection
Collection3 (c, a key)
C
ABC
Def
Ghi
LMN
Opq
RST
Key to take is not important
CodePudding user response:
The above I describe not clear collection1 (a, key1) collection1 (b, key2)Want to combine the two, put a set of two merged into a set of key corresponding to the two groups of collection collection collection1 (ab, key)