Hi all, I have a sequence of {:key K :value V} maps. There is no guarantee that there is one map for every known K. I need to ensure that there is a map for each known K.
Imagine the sequence represents a distribution between 1 and 5. The initial sequence might only be [{:key 3 :value 30} {:key 4 :value 40}]. I want it to be [{:key 1 :value nil} {:key 2 :value nil} {:key 3 :value 30} {:key 4 :value 40} {:key 5 :value nil}]. (There is a sensible reason for {:key K :value V} rather than {K V} by the way, but it would be possible to temporarily represent the sequence as [K1 V1 K2 V2] and then convert it back.) In Java I would do something like: // create a convenient look up to avoid nasty N^2 lookups Map<Object, Object> keyToValue = new HashMap.... for (Map<Object, Object> kvMap: kvSequence) keyToValue.put(kvMap.get("key"), kvMap.put("value")); List<Object> allKeys = calculateAllKeys(); List<Map<Object, Object>> results = new Array.... for (Object key: allKeys) Object result = keyToValue.get(key); // null is fine for missing keys results.put(key, result); return results; What is the (far more elegant and succinct!) way in Clojure? My intuition says something like create a map of K/V (i.e. {k1 nil k2 nil}) for all known keys, convert the existing sequence of maps into a flattened map, merge them together allowing the original sequence to take precedence and then group them back into [{:key k1 :value v1} {:key k2 :value v2}]. Any hints/clues - is this the right approach? Thanks a bunch! Col -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.