setbiome.py

#!/usr/bin/env python
import redstone as rs
import sys

try:
    biome = int(sys.argv[1])
    files = sys.argv[2:]
except:
    print "usage: {0} <biome> <region.mca ...>".format(sys.argv[0])
    sys.exit(1)

for fname in files:
    print "setting biome in", fname
    r = rs.Region.open(fname, True)
    for x in xrange(32):
        for z in xrange(32):
            if not r.contains_chunk(x, z):
                continue
            d = rs.NBT.parse_from_region(r, x, z)
            biomes = d.find("Biomes")
            biomes.value = chr(biome) * (16 * 16)
            d.write_to_region(r, x, z)
    r.flush()