first commit

public/py/sgp4/alpha5.py

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+"""Alpha 5 encoding of satellite numbers to fit in 5 characters."""
+
+def to_alpha5(n):
+    if n < 100000:
+        return '%05d' % n
+    if n > 339999:
+        raise ValueError('satellite number cannot exceed 339999,'
+                         " whose Alpha 5 encoding is 'Z9999'")
+    i, n = divmod(n, 10000)
+    i += ord('A') - 10
+    if i >= ord('I'): i += 1
+    if i >= ord('O'): i += 1
+    return '%c%04d' % (i, n)
+
+def from_alpha5(s):
+    if not s[0].isalpha():
+        return int(s)
+    c, s = s[0], s[1:]
+    n = ord(c) - ord('A') + 10
+    n -= c > 'I'
+    n -= c > 'O'
+    return n * 10000 + int(s)