diff --git a/.gitignore b/.gitignore
index 774c318..f7ed97c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,4 @@
 teststore
 .DS_Store
 bin
+.idea
diff --git a/genomix/genomix-hadoop/src/test/python/convert_graphviz.py b/genomix/genomix-hadoop/src/test/python/convert_graphviz.py
index fe9b778..4130052 100755
--- a/genomix/genomix-hadoop/src/test/python/convert_graphviz.py
+++ b/genomix/genomix-hadoop/src/test/python/convert_graphviz.py
@@ -100,7 +100,7 @@
 
     parser.add_argument('txt_graphs', nargs='*')
     parser.add_argument('--directory', '-d', help='Recurse here and plot all '
-                        'graphs that are found.', nargs='+', default=[])
+                        'graphs that are found.', action='append', default=[])
     return parser
 
 
diff --git a/genomix/genomix-hadoop/src/test/python/generate_graph.py b/genomix/genomix-hadoop/src/test/python/generate_graph.py
new file mode 100644
index 0000000..2053bf9
--- /dev/null
+++ b/genomix/genomix-hadoop/src/test/python/generate_graph.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+Generate a random smattering of reads
+"""
+
+import sys
+import argparse
+import random
+import itertools
+import string
+
+
+def get_parser():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--walk', '-w', action='store_true')
+    parser.add_argument('--coverage', '-c', type=float, required=True)
+    parser.add_argument('--genome-length', '-g', type=int,
+                        required=True)
+    parser.add_argument('--read-length', '-l', type=int, required=True)
+    parser.add_argument('--no-rc', action='store_true')
+    parser.add_argument('--error-rate', type=float, default=.01)
+    parser.add_argument('--outreads', '-r', type=argparse.FileType('w'),
+                        default='reads.txt')
+    parser.add_argument('--outgenome', '-o', type=argparse.FileType('w'),
+                        default='genome.txt')
+    return parser
+
+
+def reverse_complement(kmer, _table=string.maketrans('ACGT', 'TGCA')):
+    return string.translate(kmer, _table)[::-1]
+
+
+def make_genome(length):
+    return ''.join(random.choice('ACGT') for i in xrange(length))
+
+
+def make_reads(genome, read_length, coverage, walk=False, no_rc=False,
+               error_rate=0.):
+    num_reads = int(coverage * len(genome)) / read_length
+    if walk:
+        step_size = max(1, int(len(genome) / num_reads))
+        next_starts = itertools.cycle(xrange(0, len(genome) - read_length + 1,
+                                            step_size))
+    else:
+        next_starts = (random.randrange(len(genome) - read_length) for i in itertools.cycle([None]))
+    num_errors = 0
+    for i in range(1, num_reads + 1):
+        start = next_starts.next()
+        seq = genome[start:start + read_length]
+        if not no_rc and random.choice([True, False]):
+            seq = reverse_complement(seq)
+        final_seq = []
+        for l in seq:
+            if random.random() < error_rate:
+                num_errors += 1
+                final_seq.append(random.choice(list(set('ATGC') - set(l))))
+            else:
+                final_seq.append(l)
+
+        yield '%s\t%s\n' % (i, ''.join(final_seq))
+    print >> sys.stderr, 'introduced', num_errors, 'errors'
+
+
+def main(args):
+    parser = get_parser()
+    args = parser.parse_args(args)
+    genome = make_genome(args.genome_length)
+    args.outgenome.write(genome)
+    args.outgenome.write('\n')
+    args.outreads.writelines(make_reads(genome, args.read_length,
+                                        args.coverage, args.walk, args.no_rc,
+                                        args.error_rate))
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])
diff --git a/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq1.txt b/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq1.txt
new file mode 100644
index 0000000..35f1c49
--- /dev/null
+++ b/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq1.txt
@@ -0,0 +1,37 @@
+1	TAGTGCGA
+2	CCTCGCAC
+3	GCTAGGGT
+4	GAGGGTTG
+5	AGCAACCC
+6	GTTGCTGA
+7	TTTCAGCA
+8	CTGAAATC
+9	CAGATTTC
+10	GGCAGATT
+11	CTGGCAGA
+12	CTCTGGCA
+13	ATCTCTGG
+14	GCATCTCT
+15	CGGCATCT
+16	AACGGCAT
+17	GAAACGGC
+18	CGTTTCAA
+19	TATTGAAA
+20	TCAATACG
+21	AATACGTG
+22	TACGTGAA
+23	GTTTCACG
+24	TGAAACTA
+25	AAACTATT
+26	GTAATAGT
+27	TATTACGT
+28	TTACGTCA
+29	CATGACGT
+30	GTCATGAC
+31	GCGTCATG
+32	AAGCGTCA
+33	TCGCTTAA
+34	GCTTAAGC
+35	TCGCTTAA
+36	AAGCGTGT
+37	CCACACGC
diff --git a/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq2.txt b/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq2.txt
new file mode 100644
index 0000000..d65f7c0
--- /dev/null
+++ b/genomix/genomix-hadoop/src/test/resources/data/sequence/walk_random_seq2.txt
@@ -0,0 +1,6 @@
+1	AATGCGCT
+2	CTAGCGCA
+3	CGCTAGGA
+4	CTAGGAGT
+5	AGGAGTTG
+6	AGCGCATT