MC Schematic to Bill of Materials

bom.py

import nbt, sys

if len(sys.argv) > 1:
    f = open(sys.argv[1], 'rb')
else:
    f = sys.stdin

n = nbt.nbt.NBTFile(fileobj = f)

pal = {v.value: v.name.partition('[')[0] for v in n['Palette'].values()}
counts = {v: n['BlockData'].value.count(v) for v in pal.keys()}

bom = {}
for k, v in counts.items():
    bom.setdefault(pal[k], 0)
    bom[pal[k]] += v

for nm, ct in sorted(bom.items(), key = lambda p: p[1], reverse = True):
    pnm = nm.partition(':')[2] if nm.startswith('minecraft:') else nm
    print(f'- {pnm}: {ct}')

Python 3, depends on twoolie's NBT: pip3 install NBT