Re: Get digits of a number
yes... it would be better. On Sun, Jan 20, 2013 at 2:30 AM, David Brown cloj...@davidb.org wrote: Qiu Xiafei qiuxia...@gmail.com writes: (defn num-digits [num] (loop [n num res []] (if (zero? n) res (recur (long (/ n 10)) (cons (mod n 10) res) How about (quot n 10) instead of (long (/ n 10))? No sense in the extra step. David -- 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 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: Get digits of a number
(defn num-digits [num] (loop [n num res []] (if (zero? n) res (recur (long (/ n 10)) (cons (mod n 10) res) 在 2011年2月17日星期四UTC+8下午1时29分10秒，Andreas Kostler写道： Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... Andreas -- 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: Get digits of a number
Qiu Xiafei qiuxia...@gmail.com writes: (defn num-digits [num] (loop [n num res []] (if (zero? n) res (recur (long (/ n 10)) (cons (mod n 10) res) How about (quot n 10) instead of (long (/ n 10))? No sense in the extra step. David -- 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: Get digits of a number
On Thu, Feb 17, 2011 at 1:39 AM, Shantanu Kumar kumar.shant...@gmail.com wrote: On Feb 17, 11:09 am, Ken Wesson kwess...@gmail.com wrote: On Thu, Feb 17, 2011 at 12:29 AM, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... How about (defn explode-to-digits [n] (if (= n 0) [] (let [d (rem n 10) r (quot n 10)] (conj (explode-to-digits r) d or if you want to avoid consuming stack (defn explode-to-digits* [n out] (if (= n 0) out (let [d (rem n 10) r (quot n 10)] (recur r (cons d out) (defn explode-to-digits [n] (explode-to-digits* n nil)) It should also be possible to make a lazy sequence version, but returning the digits in the reverse order. A bit shorter: (defn digits [n] (let [r (rem n 10) q (int (/ n 10)) _ (println (format q=%d, r=%d q r))] (if (zero? q) [r] (into [r] (digits q) Not efficient though. If you really want efficient: (defn digits [n] (loop [n (int n) out nil] (if (zero? n) out (recur (unchecked-divide n 10) (cons (unchecked-remainder n 10) out) If you really /really/ want efficient: (defn digits [n dig-max] (let [a (int-array dig-max)] (loop [n (int n) i (int (dec dig-max))] (when-not (zero? n) (aset a i (unchecked-remainder n 10)) (recur (unchecked-divide n 10) (unchecked-dec i (seq a))) Icky but should be fastest possible in Clojure. This one will throw an exception if dig-max is too small and produce leading zeros if it's bigger than the number of digits of n, and it will truncate inputs that don't fit in a 32-bit signed int. You can wrap in (drop-while zero? ...) to lose the latter behavior but it will slow things down, or use Math/log10 and slow things down even more. All of the variations I've posted will turn negative numbers into seqs of digits that are all negated, e.g. (-1 0 -2 -4 -5 -6) and are liable to hang, blow the heap (pretty slowly), or blow the stack (variously) on fractions of any kind (Ratios, doubles, etc.). In practice, if I needed something like this in production code, I'd probably use one of the nicely idiomatic versions from earlier -- after all, the complexity is logarithmic in the magnitudes of the numbers you're using anyway -- and handle negative and fractional inputs in some more elegant manner. I'd probably also generalize it to accept an arbitrary radix as an optional second parameter. This would simply replace all the literal 10s in the code. It too would need to be sanity checked, for being an integer and = 2. -- 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: Get digits of a number
On Feb 16, 10:29 pm, Andreas Kostler
andreas.koestler.le...@gmail.com wrote:
Is there an easy and idiomatic way of getting the digits of a number in
clojure?
Here is my attempt at this from a few months ago:
(defn to-digit
Create a seq of digits from a number.
^{:user/comment For Euler Problems (Specifically 16)}
[i {:keys [type] :or {type int}}]
(let [ss (str i)] (map type (map (fn [s] (- (int s) 48)) ss
I took a more pragmatic approach to this problem and just assumed the
representation for digits was ASCII. It's possible to simplify this
some but, as is, it'll take seqs of characters or strings. At the time
I remember thinking this function should really return bytes or shorts
or something smaller than an int. Thus the :type option.
JMatt
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Re: Get digits of a number
On Thu, 17 Feb 2011 10:26:05 -0800 (PST)
JMatt jm...@jmatt.org wrote:
On Feb 16, 10:29 pm, Andreas Kostler
andreas.koestler.le...@gmail.com wrote:
Is there an easy and idiomatic way of getting the digits of a number in
clojure?
Here is my attempt at this from a few months ago:
My turn...
(defn to-digits
Create a seq of digits from a number.
[i]
^{:user/comment For Euler Problems (Specifically 16)}
(map {\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9}
(str i)))
No assumption about representation here. But my Python background is
showing - Pythons dictionaries are used *everywhere* in the language,
and hence tuned as tightly as possible and thus blasted fast.
mike
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Re: Get digits of a number
On Feb 17, 2011, at 1:36 PM, Mike Meyer wrote:
My turn...
(defn to-digits
Create a seq of digits from a number.
[i]
^{:user/comment For Euler Problems (Specifically 16)}
(map {\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9}
(str i)))
No assumption about representation here. But my Python background is
showing - Pythons dictionaries are used *everywhere* in the language,
and hence tuned as tightly as possible and thus blasted fast.
Why not use Character/digit, as Saul suggested?
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Re: Get digits of a number
On Thu, 17 Feb 2011 15:27:47 -0600
Michael Gardner gardne...@gmail.com wrote:
On Feb 17, 2011, at 1:36 PM, Mike Meyer wrote:
My turn...
(defn to-digits
Create a seq of digits from a number.
[i]
^{:user/comment For Euler Problems (Specifically 16)}
(map {\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9}
(str i)))
Why not use Character/digit, as Saul suggested?
Because I'm not a java programmer, so my natural inclination is to use
Clojure tools (like the hashmap) rather than Java tools. Since I
hadn't seen a solutions using the hashamp - but had seen some more
complex variants - I thought this one might be of interest.
mike
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Re: Get digits of a number
How about using the Java api Character/getNumbericValue, like so:
(defn explode-to-digits [number]
(map #(Character/getNumericValue %) (str number)))
user = (explode-to-digits 12345)
(1 2 3 4 5)
On Feb 17, 4:45 pm, Mike Meyer m...@mired.org wrote:
On Thu, 17 Feb 2011 15:27:47 -0600
Michael Gardner gardne...@gmail.com wrote:
On Feb 17, 2011, at 1:36 PM, Mike Meyer wrote:
My turn...
(defn to-digits
Create a seq of digits from a number.
[i]
^{:user/comment For Euler Problems (Specifically 16)}
(map {\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9}
(str i)))
Why not use Character/digit, as Saul suggested?
Because I'm not a java programmer, so my natural inclination is to use
Clojure tools (like the hashmap) rather than Java tools. Since I
hadn't seen a solutions using the hashamp - but had seen some more
complex variants - I thought this one might be of interest.
mike
--
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Re: Get digits of a number
I normally use
(defn digits [n]
(map #(Integer/parseInt (str %)) (seq (str n
You can adapt it to read in different bases easily.
sincerely,
--Robert McIntyre
On Thu, Feb 17, 2011 at 9:45 PM, Matthew Boston
matthew.bos...@gmail.com wrote:
How about using the Java api Character/getNumbericValue, like so:
(defn explode-to-digits [number]
(map #(Character/getNumericValue %) (str number)))
user = (explode-to-digits 12345)
(1 2 3 4 5)
On Feb 17, 4:45 pm, Mike Meyer m...@mired.org wrote:
On Thu, 17 Feb 2011 15:27:47 -0600
Michael Gardner gardne...@gmail.com wrote:
On Feb 17, 2011, at 1:36 PM, Mike Meyer wrote:
My turn...
(defn to-digits
Create a seq of digits from a number.
[i]
^{:user/comment For Euler Problems (Specifically 16)}
(map {\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9}
(str i)))
Why not use Character/digit, as Saul suggested?
Because I'm not a java programmer, so my natural inclination is to use
Clojure tools (like the hashmap) rather than Java tools. Since I
hadn't seen a solutions using the hashamp - but had seen some more
complex variants - I thought this one might be of interest.
mike
--
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Independent Software developer/SCM consultant, email for more information.
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Get digits of a number
Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... Andreas -- 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: Get digits of a number
On Feb 17, 6:29 am, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) I'd do it this way: (defn explode-to-digits [number] (seq (str number))) Saul -- 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: Get digits of a number
Hi Saul, (defn explode-to-digits [number] (seq (str number))) This gives you a sequence of character representations for the digits e.g: (explode-to-digits 1234) = (\1 \2 \3 \4) On 17/02/2011, at 4:01 PM, Saul Hazledine wrote: On Feb 17, 6:29 am, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) I'd do it this way: (defn explode-to-digits [number] (seq (str number))) Saul -- 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 -- Programs must be written for people to read, and only incidentally for machines to execute. - Abelson Sussman, SICP -- ** Andreas Koestler, Software Engineer Leica Geosystems Pty Ltd 270 Gladstone Road, Dutton Park QLD 4102 Main: +61 7 3891 9772 Direct: +61 7 3117 8808 Fax: +61 7 3891 9336 Email: andreas.koest...@leica-geosystems.com www.leica-geosystems.com* when it has to be right, Leica Geosystems Please consider the environment before printing this email. -- 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: Get digits of a number
On Feb 17, 6:29 am, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Sorry, my first answer was careless and stupid - this time with numbers: (defn explode-to-digits [number] (map #(Character/digit % 10) (str number))) Saul -- 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: Get digits of a number
On Feb 17, 11:09 am, Ken Wesson kwess...@gmail.com wrote: On Thu, Feb 17, 2011 at 12:29 AM, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... How about (defn explode-to-digits [n] (if (= n 0) [] (let [d (rem n 10) r (quot n 10)] (conj (explode-to-digits r) d or if you want to avoid consuming stack (defn explode-to-digits* [n out] (if (= n 0) out (let [d (rem n 10) r (quot n 10)] (recur r (cons d out) (defn explode-to-digits [n] (explode-to-digits* n nil)) It should also be possible to make a lazy sequence version, but returning the digits in the reverse order. A bit shorter: (defn digits [n] (let [r (rem n 10) q (int (/ n 10)) _ (println (format q=%d, r=%d q r))] (if (zero? q) [r] (into [r] (digits q) Not efficient though. Regards, Shantanu -- 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: Get digits of a number
On Feb 17, 11:39 am, Shantanu Kumar kumar.shant...@gmail.com wrote: On Feb 17, 11:09 am, Ken Wesson kwess...@gmail.com wrote: On Thu, Feb 17, 2011 at 12:29 AM, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... How about (defn explode-to-digits [n] (if (= n 0) [] (let [d (rem n 10) r (quot n 10)] (conj (explode-to-digits r) d or if you want to avoid consuming stack (defn explode-to-digits* [n out] (if (= n 0) out (let [d (rem n 10) r (quot n 10)] (recur r (cons d out) (defn explode-to-digits [n] (explode-to-digits* n nil)) It should also be possible to make a lazy sequence version, but returning the digits in the reverse order. A bit shorter: (defn digits [n] (let [r (rem n 10) q (int (/ n 10)) _ (println (format q=%d, r=%d q r))] (if (zero? q) [r] (into [r] (digits q) Not efficient though. Oops, the earlier version that uses conj is shorter indeed. Cheers, Shantanu -- 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: Get digits of a number
On Thu, Feb 17, 2011 at 12:29 AM, Andreas Kostler andreas.koestler.le...@gmail.com wrote: Is there an easy and idiomatic way of getting the digits of a number in clojure? (defn explode-to-digits [number] (map #(- (int %) (int \0)) (str number))) (explode-to-digits 123456) = (1 2 3 4 5 6) Seems a bit clunky... How about (defn explode-to-digits [n] (if (= n 0) [] (let [d (rem n 10) r (quot n 10)] (conj (explode-to-digits r) d or if you want to avoid consuming stack (defn explode-to-digits* [n out] (if (= n 0) out (let [d (rem n 10) r (quot n 10)] (recur r (cons d out) (defn explode-to-digits [n] (explode-to-digits* n nil)) It should also be possible to make a lazy sequence version, but returning the digits in the reverse order. -- 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
