Initial data commit

Task/Burrows-Wheeler-transform/Python/burrows-wheeler-transform.py

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+def bwt(s):
+    """Apply Burrows-Wheeler transform to input string."""
+    assert "\002" not in s and "\003" not in s, "Input string cannot contain STX and ETX characters"
+    s = "\002" + s + "\003"  # Add start and end of text marker
+    table = sorted(s[i:] + s[:i] for i in range(len(s)))  # Table of rotations of string
+    last_column = [row[-1:] for row in table]  # Last characters of each row
+    return "".join(last_column)  # Convert list of characters into string
+
+
+def ibwt(r):
+    """Apply inverse Burrows-Wheeler transform."""
+    table = [""] * len(r)  # Make empty table
+    for i in range(len(r)):
+        table = sorted(r[i] + table[i] for i in range(len(r)))  # Add a column of r
+    s = [row for row in table if row.endswith("\003")][0]  # Find the correct row (ending in ETX)
+    return s.rstrip("\003").strip("\002")  # Get rid of start and end markers