Add: julia-0.6.2

Former-commit-id: ccc667cf67d569f3fb3df39aa57c2134755a7551

julia-0.6.2/share/doc/julia/examples/wordcount.jl

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+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# wordcount.jl
+#
+# Implementation of parallelized "word-count" of a text, inspired by the
+# Hadoop WordCount example. Uses @spawn and fetch() to parallelize
+# the "map" task. Reduce is currently done single-threaded.
+#
+# To run in parallel on a string stored in variable `text`:
+#  julia -p <N>
+#  julia> require("<julia_doc_dir>/examples/wordcount.jl")
+#  julia> ...(define text)...
+#  julia> counts=parallel_wordcount(text)
+#
+# Or to run on a group of files, writing results to an output file:
+#  julia -p <N>
+#  julia> require("<julia_doc_dir>/examples/wordcount.jl")
+#  julia> wordcount_files("/tmp/output.txt", "/tmp/input1.txt","/tmp/input2.txt",...)
+
+# "Map" function.
+# Takes a string. Returns a Dict with the number of times each word
+# appears in that string.
+function wordcount(text)
+    words=split(text,[' ','\n','\t','-','.',',',':',';'];keep=false)
+    counts=Dict()
+    for w = words
+        counts[w]=get(counts,w,0)+1
+    end
+    return counts
+end
+
+# "Reduce" function.
+# Takes a collection of Dicts in the format returned by wordcount()
+# Returns a Dict in which words that appear in multiple inputs
+# have their totals added together.
+function wcreduce(wcs)
+    counts=Dict()
+    for c in wcs, (k,v) in c
+        counts[k] = get(counts,k,0)+v
+    end
+    return counts
+end
+
+# Splits input string into nprocs() equal-sized chunks (last one rounds up),
+# and @spawns wordcount() for each chunk to run in parallel. Then fetch()s
+# results and performs wcreduce().
+function parallel_wordcount(text)
+    lines=split(text,'\n';keep=false)
+    np=nprocs()
+    unitsize=ceil(length(lines)/np)
+    wcounts=[]
+    rrefs=[]
+    # spawn procs
+    for i=1:np
+        first=unitsize*(i-1)+1
+        last=unitsize*i
+        if last>length(lines)
+            last=length(lines)
+        end
+        subtext=join(lines[Int(first):Int(last)],"\n")
+        push!(rrefs, @spawn wordcount( subtext ) )
+    end
+    # fetch results
+    while length(rrefs)>0
+        push!(wcounts,fetch(pop!(rrefs)))
+    end
+    # reduce
+    count=wcreduce(wcounts)
+    return count
+end
+
+# Takes the name of a result file, and a list of input file names.
+# Combines the contents of all files, then performs a parallel_wordcount
+# on the resulting string. Writes the results to result_file.
+function wordcount_files(result_file,inputs...)
+    text = ""
+    for file in inputs
+        text *= readstring(file)
+    end
+    wc = parallel_wordcount(text)
+    open(result_file,"w") do f
+        for (k,v) in wc
+            println(f, k,"=",v)
+        end
+    end
+end