Re: Changing keys in a map
On Thu, Sep 30, 2010 at 11:54 PM, David Sletten da...@bosatsu.net wrote: Sean, Sean...I was just making fun of your signature. :) Phew! Just checking... (I'm on some lists where the response to similar questions has been You want me to do your homework?...) -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Re: Changing keys in a map
Sean, Sean...I was just making fun of your signature. :) Phew! Just checking... (I'm on some lists where the response to similar questions has been You want me to do your homework?...) The Clojure community is certainly not one of those. Regards, BG -- Baishampayan Ghose b.ghose at gmail.com -- 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
Re: Changing keys in a map
On Oct 1, 2010, at 1:57 AM, Sean Corfield wrote: On Thu, Sep 30, 2010 at 12:52 AM, David Sletten da...@bosatsu.net wrote: Huh?! How many solutions do you want? You're starting to annoy me Sean. Sorry dude. I think it's really insightful to see lots of different solutions to small point problems like this when you're learning a language - particularly when the issue of idiom is being discussed. I've certainly found this thread educational and I hope I'm not annoying too many people :) Sean, Sean...I was just making fun of your signature. :) Keep up the questions! If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Changing keys in a map
I have a need to convert maps in the following ways:
Given a map with keyword keys, I need a map with uppercase string keys
- and vice versa.
{ :stuff 42 :like 13 :this 7 } = { STUFF 42 LIKE 13 THIS 7 }
I've come up with various functions to do this but so far they all
feel a bit clunky.
Any suggestions for the simplest, most idiomatic solution?
Here's one pair of functions I came up with...
(defn- to-struct [r] (apply hash-map (flatten (map (fn [[k v]]
[(s/upper-case (name k)) v]) r
(defn- to-rec [m] (apply hash-map (flatten (map (fn [[k v]] [(keyword
(s/lower-case k)) v]) m
s is clojure.string:
(:use [clojure.string :as s :only (lower-case upper-case)])
I came up with some using assoc and/or dissoc as well... didn't like
those much either :)
--
Sean A Corfield -- (904) 302-SEAN
Railo Technologies, Inc. -- http://getrailo.com/
An Architect's View -- http://corfield.org/
If you're not annoying somebody, you're not really alive.
-- Margaret Atwood
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Re: Changing keys in a map
I have a need to convert maps in the following ways:
Given a map with keyword keys, I need a map with uppercase string keys
- and vice versa.
{ :stuff 42 :like 13 :this 7 } = { STUFF 42 LIKE 13 THIS 7 }
What about this -
(into {} (for [[k v] { :stuff 42 :like 13 :this 7 }]
[(.toUpperCase (name k)) v]))
Regards,
BG
--
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b.ghose at gmail.com
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Re: Changing keys in a map
On Sep 30, 2010, at 2:53 AM, Baishampayan Ghose wrote:
I have a need to convert maps in the following ways:
Given a map with keyword keys, I need a map with uppercase string keys
- and vice versa.
{ :stuff 42 :like 13 :this 7 } = { STUFF 42 LIKE 13 THIS 7 }
What about this -
(into {} (for [[k v] { :stuff 42 :like 13 :this 7 }]
[(.toUpperCase (name k)) v]))
One small suggestion based on something Christophe Grand once pointed out:
(defn string-keys [m]
(into (empty m) (for [[k v] m] [(.toUpperCase (name k)) v])))
(defn keyword-keys [m]
(into (empty m) (for [[k v] m] [(keyword (.toLowerCase k)) v])))
This will preserve the type of the map.
(string-keys { :stuff 42 :like 13 :this 7 } ) = {THIS 7, LIKE 13, STUFF
42}
(keyword-keys (string-keys { :stuff 42 :like 13 :this 7 } )) = {:stuff 42,
:like 13, :this 7}
Have all good days,
David Sletten
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Re: Changing keys in a map
On Wed, Sep 29, 2010 at 11:53 PM, Baishampayan Ghose b.gh...@gmail.com wrote:
(into {} (for [[k v] { :stuff 42 :like 13 :this 7 }]
[(.toUpperCase (name k)) v]))
(defn- to-struct [r] (into {} (for [[k v] r] [(.toUpperCase (name k)) v]))
That is certainly nicer than most of my attempts, thank you!
Any reason for .toUpperCase instead of clojure.string/upper-case?
Thanx also to David for the (empty m) tip (but I'm only working with
hash maps at the moments).
--
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Railo Technologies, Inc. -- http://getrailo.com/
An Architect's View -- http://corfield.org/
If you're not annoying somebody, you're not really alive.
-- Margaret Atwood
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Re: Changing keys in a map
On Wed, Sep 29, 2010 at 11:53 PM, Baishampayan Ghose b.gh...@gmail.com
wrote:
(into {} (for [[k v] { :stuff 42 :like 13 :this 7 }]
[(.toUpperCase (name k)) v]))
(defn- to-struct [r] (into {} (for [[k v] r] [(.toUpperCase (name k)) v]))
That is certainly nicer than most of my attempts, thank you!
Any reason for .toUpperCase instead of clojure.string/upper-case?
clojure.contrib.string/upper-case is a trivial wrapper over
.toUpperCase. In my humble opinion it's perfectly OK to use such
static Java methods directly instead of writing trivial wrappers
around them.
This also helps in avoiding the contrib dependency.
Regards,
BG
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b.ghose at gmail.com
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Re: Changing keys in a map
On Thu, Sep 30, 2010 at 12:24 AM, Baishampayan Ghose b.gh...@gmail.com wrote: This also helps in avoiding the contrib dependency. Good point. Thanx BG. -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Re: Changing keys in a map
On Thu, Sep 30, 2010 at 12:24 AM, Baishampayan Ghose b.gh...@gmail.com wrote: clojure.contrib.string/upper-case is a trivial wrapper over .toUpperCase. In my humble opinion it's perfectly OK to use such static Java methods directly instead of writing trivial wrappers around them. Except that if you use .toUpperCase, you have to remember to type hint the input. Any time you call a Java method without type hinting, you take a significant performance hit. The wrapper function takes care of that for you. -- 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
Re: Changing keys in a map
On Thu, Sep 30, 2010 at 12:18 AM, Meikel Brandmeyer m...@kotka.de wrote: (defn to-string-keys [m] (zipmap (map (comp clojure.string/upper-case name) (keys m)) (vals m))) That's very similar to one of my attempts and... I don't know... I just don't like it as much. Splitting the map into two streams and zipping them back together just doesn't feel as 'nice' and making one pass over the key/value pairs of the map... Interesting choice of comp - I think I went with #(s/upper-case (name %)) - I guess comp is more idiomatic, functionally? -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Re: Changing keys in a map
On Thu, Sep 30, 2010 at 12:30 AM, Mark Engelberg mark.engelb...@gmail.com wrote: Except that if you use .toUpperCase, you have to remember to type hint the input. Any time you call a Java method without type hinting, you take a significant performance hit. The wrapper function takes care of that for you. Good to know, thanx Mark. Keep 'em coming folks, this is exactly what I was hoping for when I posted the question. -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Re: Changing keys in a map
On Sep 30, 2010, at 3:40 AM, Sean Corfield wrote: On Thu, Sep 30, 2010 at 12:30 AM, Mark Engelberg mark.engelb...@gmail.com wrote: Except that if you use .toUpperCase, you have to remember to type hint the input. Any time you call a Java method without type hinting, you take a significant performance hit. The wrapper function takes care of that for you. Good to know, thanx Mark. Keep 'em coming folks, this is exactly what I was hoping for when I posted the question. Huh?! How many solutions do you want? You're starting to annoy me Sean. Hmm, I guess you must really be alive. :) If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
Re: Changing keys in a map
Hi, On 30 Sep., 09:37, Sean Corfield seancorfi...@gmail.com wrote: That's very similar to one of my attempts and... I don't know... I just don't like it as much. Splitting the map into two streams and zipping them back together just doesn't feel as 'nice' and making one pass over the key/value pairs of the map... The two passes are an argument. I - personally - like the split, because it makes clear that the values are not touched, while they are carried as dead weight in the one solutions. Interesting choice of comp - I think I went with #(s/upper-case (name %)) - I guess comp is more idiomatic, functionally? Dunno. I don't use it very often. I normally also use #() but in this case it was nice and clean. Sincerely Meikel -- 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
Re: Changing keys in a map
#(s/upper-case (name %)) Good and clear in this case. #(- % name s/upper-case) I think that would be nice if there were three functions. (comp s/upper-case name) I think its hard to read for beginners, because you have to read it backwards and no parens to indicate but you could say that the have to get used to it. On Sep 30, 10:09 am, Meikel Brandmeyer m...@kotka.de wrote: Hi, On 30 Sep., 09:37, Sean Corfield seancorfi...@gmail.com wrote: That's very similar to one of my attempts and... I don't know... I just don't like it as much. Splitting the map into two streams and zipping them back together just doesn't feel as 'nice' and making one pass over the key/value pairs of the map... The two passes are an argument. I - personally - like the split, because it makes clear that the values are not touched, while they are carried as dead weight in the one solutions. Interesting choice of comp - I think I went with #(s/upper-case (name %)) - I guess comp is more idiomatic, functionally? Dunno. I don't use it very often. I normally also use #() but in this case it was nice and clean. Sincerely Meikel -- 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
Re: Changing keys in a map
I wrote a blog recently on a helper function I use for stuff like this
called mapmap:
http://tech.puredanger.com/2010/09/24/meet-my-little-friend-mapmap/
mapmap takes a function to generate keys and a function to generate
values, applies them to a sequence, and zipmaps their results. Using
a map as the sequence, you'd do something like:
(mapmap #(upper-case (key %)) identity m)
If you wanted to upper-case the values, mapmap uses identity as a
default key function, so you'd do:
(mapmap #(upper-case (val %)) m)
Someone suggested on twitter that a helper function over it
specifically for working from an existing map and splitting the key
and val might be nicer. mapmap on map would of course be:
(defn mapmapmap [kf vf m]
(mapmap (comp kf key) (comp vf val) m))
Then you could use the cleaner form for your needs:
(mapmapmap upper-case identity { abc def ghi jkl })
{GHI jkl, ABC def}
From a readability perspective, I think that's nice. Feel free to
throw plenty of rocks at the function names and impl though. :)
On Sep 30, 1:44 am, Sean Corfield seancorfi...@gmail.com wrote:
I have a need to convert maps in the following ways:
Given a map with keyword keys, I need a map with uppercase string keys
- and vice versa.
{ :stuff 42 :like 13 :this 7 } = { STUFF 42 LIKE 13 THIS 7 }
I've come up with various functions to do this but so far they all
feel a bit clunky.
Any suggestions for the simplest, most idiomatic solution?
Here's one pair of functions I came up with...
(defn- to-struct [r] (apply hash-map (flatten (map (fn [[k v]]
[(s/upper-case (name k)) v]) r
(defn- to-rec [m] (apply hash-map (flatten (map (fn [[k v]] [(keyword
(s/lower-case k)) v]) m
s is clojure.string:
(:use [clojure.string :as s :only (lower-case upper-case)])
I came up with some using assoc and/or dissoc as well... didn't like
those much either :)
--
Sean A Corfield -- (904) 302-SEAN
Railo Technologies, Inc. --http://getrailo.com/
An Architect's View --http://corfield.org/
If you're not annoying somebody, you're not really alive.
-- Margaret Atwood
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Re: Changing keys in a map
On Thu, Sep 30, 2010 at 12:52 AM, David Sletten da...@bosatsu.net wrote: Huh?! How many solutions do you want? You're starting to annoy me Sean. Sorry dude. I think it's really insightful to see lots of different solutions to small point problems like this when you're learning a language - particularly when the issue of idiom is being discussed. I've certainly found this thread educational and I hope I'm not annoying too many people :) Things I'm finding particularly helpful: * into / for * comp vs #() vs - * split a map and zip it vs a single pass with a more complex function The into / for thing was great because it's something that seems very Clojurish that I wouldn't have thought of without input. I'm very excited about Clojure. I think it's going to be core to my team's work over the next couple of years. I haven't been able to do serious functional programming for about three decades but Clojure really provides that option. We're already using Scala for certain performance-critical pieces of our system but it's not a language that I can present to most of my web developers - they're used to dynamic scripting languages, no type system, no compile/deploy/run cycle. -- Sean A Corfield -- (904) 302-SEAN Railo Technologies, Inc. -- http://getrailo.com/ An Architect's View -- http://corfield.org/ If you're not annoying somebody, you're not really alive. -- Margaret Atwood -- 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
