Clojure example code snippets

[dokondr]

Hi!
I am thinking about using Clojure for distributed NLP.
Being an absolute newbie in Clojure I look for nice expressive code
snippets.

For example, I need an easy way to read text files such as in the
following Python code:
>>> for line in open("file.txt"):
... for word in line.split():
... if word.endswith('ing'):
... print word

What would be an equivalent of this code in Clojure?

Thanks,
Dmitri

[Meikel Brandmeyer]

Hi,

something like the following should work.

(with-open [rdr (java.io.FileReader. "file.txt")]
  (doseq [line (line-seq rdr)
          word (.split line "\\s")]
    (when (.endsWith word "ing")
      (println word))))

Sincerely
Meikel

[Jonathan Fischer Friberg]

There is clojure.contrib.duck-streams/read-lines
http://clojuredocs.org/clojure_contrib/clojure.contrib.duck-streams/read-lines

Then it's a matter of

(filter (partial re-matches #".*ing") (read-lines "/path/to/file"))

Jonathan

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[Benny Tsai]

I think there can be multiple words on each line, so they have to be split into words first.  Maybe something like:

(ns example

  (:use [clojure.contrib.duck-streams :only (read-lines)]))

(let [lines (read-lines "file.txt")

      words (mapcat #(.split % "\\s") lines)

      ing-words (filter (partial re-matches #".*ing") words)]

  (doseq [ing-word ing-words]

    (println ing-word)))

[Benny Tsai]

I think line-seq needs a java.io.BufferedReader instead of a java.io.FileReader.  clojure.java.io has a reader function that constructs a java.io.BufferedReader from a filename, so this worked for me:

(ns example

  (:use [clojure.java.io :only (reader)]))

(with-open [rdr (reader "file.txt")]

[Benny Tsai]

Oops.  Just noticed that the original was not quoted in either of my previous emails, which makes things really confusing.  My first reply (the one using read-lines) was an extension of odyssomay/Jonathan's code, and the second (with reader) was an extension of Meikel's code.  Sorry guys.

[dokondr]

Thanks everybody! The short one from Meikel (above) looks nice to
me :)

And the one from ClojureDocs too:

(defn read-lines
"Like clojure.core/line-seq but opens f with reader. Automatically
closes the reader AFTER YOU CONSUME THE ENTIRE SEQUENCE."
[f]
(let [read-line (fn this [^BufferedReader rdr]
(lazy-seq
(if-let [line (.readLine rdr)]
(cons line (this rdr))
(.close rdr))))]
(read-line (reader f))))

[Armando Blancas]

Just in case I'll mention that Meikel's use of (with-open) will
automatically close the reader.

[Andreas Kostler]

Hi Armando,
I'm working on a Clojurej library for sentiment analysis which doesn't contain everything you'd want for nlp but quite a nice subset of input modules (plain text corpora, rss feeds, html, etc...),
tokenising/normalising filters (noise removal, porter stemmer, etc), distance/similarity metrics (euclidean, cosine, peasrsons, Jaccard/Tanimoto), b-o-w vector representation, clustering (hierarchical, k-means), classification (NN, Bayes, knn), and some other little tidbits to tie up loose ends. There will be a first release in about 2-3 weeks time. If you're planning on doing work in that direction, maybe we could join forces :)
Kind Regards
Andreas

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[Ken Wesson]

On Thu, May 19, 2011 at 5:47 PM, Andreas Kostler
<andreas.koe...@gmail.com> wrote:
> Hi Armando,
> I'm working on a Clojurej library for sentiment analysis which doesn't contain everything you'd want for nlp but quite a nice subset of input modules (plain text corpora, rss feeds, html, etc...),
> tokenising/normalising filters (noise removal, porter stemmer, etc), distance/similarity metrics (euclidean, cosine, peasrsons, Jaccard/Tanimoto), b-o-w vector representation, clustering (hierarchical, k-means), classification (NN, Bayes, knn), and some other little tidbits to tie up loose ends. There will be a first release in about 2-3 weeks time. If you're planning on doing work in that direction, maybe we could join forces :)
> Kind Regards
> Andreas

Whoa, what the heck are you doing, trying to build Skynet? :)

Then again, Lisp HAS traditionally been the preferred language of AI hackers...

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Master: Your father's Lisp REPL. This is the language of a true
hacker. Not as clumsy or random as C++; a language for a more
civilized age.