data-proc: Add contents for "python" section

chapters/data-proc/support/python/cat.py

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+#!/usr/bin/env python
+
+"""
+Print lines in file.
+"""
+
+import sys
+import os
+
+
+def usage(argv0):
+    print("Usage: {} <file>".format(argv0), file=sys.stderr)
+
+
+def main():
+    if len(sys.argv) != 2:
+        usage(sys.argv[0])
+        sys.exit(1)
+
+    fname = sys.argv[1]
+    if not os.path.isfile(fname):
+        print("Argument {} is not a file.".format(fname), file=sys.stderr)
+        sys.exit(1)
+
+    with open(fname) as f:
+        lines = f.readlines()
+        for l in lines:
+            print(l.rstrip())
+
+
+if __name__ == "__main__":
+    main()

chapters/data-proc/support/python/hello.py

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+#!/usr/bin/env python3
+
+print("Hello, World!")

chapters/data-proc/support/python/hello_main.py

@@ -0,0 +1,13 @@
+#!/usr/bin/env python3
+
+"""
+Simple stupid program: print "Hello, World!" at standard output.
+"""
+
+
+def main():
+    print("Hello, World!")
+
+
+if __name__ == "__main__":
+    main()

chapters/data-proc/support/python/num_lines.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+
+"""
+Print number of lines in file.
+"""
+
+import sys
+import os
+
+
+def usage(argv0):
+    print("Usage: {} <file>".format(argv0), file=sys.stderr)
+
+
+def main():
+    if len(sys.argv) != 2:
+        usage(sys.argv[0])
+        sys.exit(1)
+
+    fname = sys.argv[1]
+    if not os.path.isfile(fname):
+        print("Argument {} is not a file.".format(fname), file=sys.stderr)
+        sys.exit(1)
+
+    with open(fname) as f:
+        lines = f.readlines()
+        num = len(lines)
+        print("Number of lines in {} is {}.".format(fname, num))
+
+
+if __name__ == "__main__":
+    main()

chapters/data-proc/support/python/sum100.py

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+#!/usr/bin/env python
+
+sum = 0
+for i in range(1, 101):
+    sum += i
+
+print("sum(1,100):", sum)

chapters/data-proc/support/python/sum_n_arg.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def usage(argv0):
+    print("Usage: {} <num>".format(argv0), file=sys.stderr)
+
+
+def main():
+    if len(sys.argv) != 2:
+        usage(sys.argv[0])
+        sys.exit(1)
+
+    sum = 0
+    try:
+        n = int(sys.argv[1])
+    except ValueError:
+        print("Argument is not an integer.", file=sys.stderr)
+        sys.exit(1)
+
+    for i in range(1, n+1):
+        sum += i
+
+    print("sum(1,{}): {}".format(n, sum))
+
+
+if __name__ == "__main__":
+    main()

chapters/data-proc/support/python/tac.py

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+#!/usr/bin/env python
+
+"""
+Print lines in file in reverse.
+"""
+
+import sys
+import os
+
+
+def usage(argv0):
+    print("Usage: {} <file>".format(argv0), file=sys.stderr)
+
+
+def main():
+    if len(sys.argv) != 2:
+        usage(sys.argv[0])
+        sys.exit(1)
+
+    fname = sys.argv[1]
+    if not os.path.isfile(fname):
+        print("Argument {} is not a file.".format(fname), file=sys.stderr)
+        sys.exit(1)
+
+    with open(fname) as f:
+        lines = f.readlines()[::-1]
+        for l in lines:
+            print(l.rstrip())
+
+
+if __name__ == "__main__":
+    main()