1 files changed, 34 insertions, 0 deletions
diff --git a/lib/nlp_ruby/stringutil.rb b/lib/nlp_ruby/stringutil.rb
new file mode 100644
index 0000000..e9a3bc9
--- /dev/null
+++ b/lib/nlp_ruby/stringutil.rb
@@ -0,0 +1,34 @@
+# whitespace 'tokenizer'
+def tokenize s
+  s.strip.split
+end
+
+def splitpipe s
+  s.strip.split(/\s*\|\|\|\s*/)
+end
+
+def downcase? s
+  s[/[[:lower:]]/]
+end
+
+# iterator over n-grams
+def ngrams(s, n, fix=false)
+  a = tokenize s
+  a.each_with_index { |tok, i|
+    tok.strip!
+    0.upto([n-1, a.size-i-1].min) { |m|
+      yield a[i..i+m] if !fix||(fix&&a[i..i+m].size==n)
+    }
+  }
+end
+
+# a=1.0 b=2.0 => { 'a' => 1.0, 'b' => 2.0 }
+def read_feature_string s
+  map = SparseVector.new
+  tokenize(s).each { |i|
+    key, value = i.split '='
+    map[key] = value.to_f
+  }
+  return map
+end
+