Even without reaching for libraries outside clojure.core, there's (update-in m [:key-of-interest] #(if (condition? %) (transformation %) %))
and the ability to convert that into a function, e.g. (defn conditional-update-in [m condition? transformation k] (update-in m [k] #(if (condition? %) (transformation %) %))) and then, if you have many keys that should undergo the same transformation under the same condition, (reduce (partial conditional-update-in m condition? transformation) [keys...]), and its encapsulation, (defn conditional-update-multi [m condition? transformation ks] (reduce (partial conditional-update-in m condition? transformation) ks)) On Fri, Jul 5, 2013 at 5:31 PM, Ben Wolfson <wolf...@gmail.com> wrote: > You could use clojure.algo.generic.functor.fmap: (fmap #(if (pred? %) > replacement-value %) your-map). > > > On Fri, Jul 5, 2013 at 2:08 PM, John Walker <jouiswal...@gmail.com> wrote: > >> I had to do something similar, and used >> clojure.walk.<http://clojuredocs.org/clojure_core/clojure.walk/walk> >> >> On Friday, July 5, 2013 8:59:54 PM UTC, Colin Yates wrote: >>> >>> Hi all, >>> >>> I think this is one of those questions which has quite a few answers, >>> but given a map, how do I replace the values by applying a function to >>> those values, but only if they meet a condition? >>> >>> I understand the building blocks of (map..), (filter..), (assoc-in..) >>> and (filter..) and I can see how something could work using those pieces >>> but is would be pretty verbose. I am sure there is probably a much more >>> simple way using a more abstract function. >>> >>> The actual use case is I have a list of maps as returned from the >>> clojure.java.jdbc framework and they contain timestamps. I want to replace >>> all the timestamps with (for example) to a Joda LocalDate using the >>> excellent clj-time library. >>> >>> Any pointers? >>> >>> Thanks! >>> >>> 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. >> >> >> > > > > -- > Ben Wolfson > "Human kind has used its intelligence to vary the flavour of drinks, which > may be sweet, aromatic, fermented or spirit-based. ... Family and social > life also offer numerous other occasions to consume drinks for pleasure." > [Larousse, "Drink" entry] > > -- > -- > 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. > > > -- -- 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.
