updated contents from Atlas repo

dicts/index_alex.py

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+# adapted from Alex Martelli's example in "Re-learning Python"
+# http://www.aleax.it/Python/accu04_Relearn_Python_alex.pdf
+# (slide 41) Ex: lines-by-word file index
+
+
+"""Build a map word -> list-of-line-numbers"""
+
+import sys
+import re
+
+NONWORD_RE = re.compile('\W+')
+
+idx = {}
+with open(sys.argv[1], encoding='utf-8') as fp:
+    for n, line in enumerate(fp, 1):
+        for word in NONWORD_RE.split(line):
+            if word.strip():
+                idx.setdefault(word, []).append(n)
+
+# print in alphabetical order
+for word in sorted(idx, key=str.upper):
+    print(word, idx[word])