1 files changed, 53 insertions, 0 deletions
diff --git a/reverse.py b/reverse.py
new file mode 100755
index 0000000..304baa1
--- /dev/null
+++ b/reverse.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+from sys import argv
+
+def int2card(num, dim=4):
+    if num != int(num):
+        raise Exception("Number must be an integer.")
+    if num < 0:
+        raise Exception("Number must be nonnegative.")
+    if num >= 3**dim:
+        raise Exception("Number must be less than {}.".format(3**dim))
+    strlist = []
+    for i in range(dim):
+        strlist.append(str(num%3))
+        num //= 3
+    return ''.join(reversed(strlist))
+
+def main():
+    """Reverses the card identities in a capset.out file.
+
+    222 becomes 000, etc.
+    By default, reads in capset.out and writes to capset.new
+    You may give other input/output files as optional arguments.
+    It will NOT reverse in-place: you must give a different output file.
+    """
+    inname = "capset.out"
+    outname = "capset.new"
+    if len(argv) == 2:
+        inname = argv[1]
+    if len(argv) == 3:
+        inname = argv[1]
+        outname = argv[2]
+        if inname == outname:
+            raise Exception("Input and output files must differ!")
+    infile = open(inname, "r")
+    outfile = open(outname, "w")
+
+    firstline = infile.readline()
+    infile.seek(0)
+    capset = firstline[1:-2].split(" ")
+    dim = len(capset[0])
+
+    for line in infile:
+        capset = line[1:-2].split(" ")
+        newcards = []
+        for card in capset:
+            newcard = 3**dim - 1 - int(card, 3)
+            newcards.append(int2card(newcard, dim))
+        outfile.write("[" + " ".join(newcards) + "]\n")
+
+    infile.close()
+    outfile.close()
+
+if __name__ == "__main__": main()