Ejercicio 8

exercises/ex08/ex08.py

@@ -0,0 +1,49 @@
+# Exercise 2
+# 1. cut command
+
+import re
+import sys
+import itertools
+import argparse
+
+
+def convert(field):
+    field = list(map(lambda f: int(f), field.split("-")))
+    if len(field) == 1:
+        return field
+    else:
+        for i in range(field[0], field[-1]):
+            field.append(i)
+        return sorted(set(field))
+
+
+def parse(fields):
+    try:
+        fields = list(map(convert, fields.split(",")))
+        fields = list(itertools.chain(*fields))
+        if 0 in fields:
+            print("cut: fields are numbered from 1")
+            sys.exit(1)
+        return list(map(lambda n: n - 1, fields))
+    except Exception:
+        print(f"cut: valor de campo inválido: «{fields}»")
+        sys.exit(1)
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument('stream', default=sys.stdin, nargs="?")
+parser.add_argument('-d', '--delimiter', default=False, type=str)
+parser.add_argument('-f', '--fields', type=str, required=True)
+args = parser.parse_args()
+
+for line in args.stream:
+    line = line.strip()
+    if args.delimiter is False:
+        print(line)
+    else:
+        fields = re.compile(f"{args.delimiter}+").split(line)
+        res = []
+        for col in parse(args.fields):
+            if col < len(fields):
+                res.append(fields[col])
+        print(" ".join(res))