Deletes all chunks that don't contain a specific block within a coordinate range. Files are read from `./region` and output to `./output`. Default scans for any glass block at y=255 in every chunk.

prune_chunks.py

# Prune Chunks
# Deletes all chunks that don't contain a specific block within a coordinate range
# By Onnowhere

import os
import sys
import subprocess
import pkg_resources
import pathlib

required = {'anvil-parser'}
installed = {pkg.key for pkg in pkg_resources.working_set}
missing = required - installed

if missing:
    print("Installing:", *missing)
    subprocess.check_call([sys.executable, "-m", "pip", "install", *missing])
import anvil

def create_path(filepath):
    if not os.path.exists(filepath):
        try:
            os.makedirs(filepath)
        except OSError as exc: # Guard against race condition
            if exc.errno != errno.EEXIST:
                raise
                
def pruneChunks(in_file, out_file, checkedblock, fixedcoord=([0,15], [255,255], [0,15]), debug=False):
    # Fixed coord can be values within: (0-15, 0-255, 0-15)
    # Defines the region to scan for a block within a chunk
    # ([0,15], [255,255], [0,15]) scans all blocks at y=255 in each chunk
    create_path(os.path.dirname(in_file))
    create_path(os.path.dirname(out_file))
    region = anvil.Region.from_file(in_file)
    print("Input:", in_file)
    file_parts = os.path.basename(in_file).split(".")
    regionx = int(file_parts[1])
    regionz = int(file_parts[2])
    if debug:
        print("Reading region at ({0}, {1})".format(regionx, regionz))
    region_out = anvil.EmptyRegion(regionx, regionz)

    chunk_count = 0
    pruned_count = 0

    for rx in range(0, 32):
        for rz in range(0, 32):
            if debug:
                print("Reading chunk at ({0}, {1})".format(rx, rz))
            try:
                chunk = anvil.Chunk.from_region(region, rx, rz)
            except:
                if debug:
                    print("Skipping chunk as empty...")
                continue
            chunk_count += 1
            
            found = False
            for posx in range(fixedcoord[0][1], fixedcoord[0][1] + 1):
                for posy in range(fixedcoord[1][1], fixedcoord[1][1] + 1):
                    for posz in range(fixedcoord[2][1], fixedcoord[2][1] + 1):
                        #print("Checking coordinate ({0}, {1}, {2})".format(posx, posy, posz))
                        block = chunk.get_block(posx, posy, posz)
                        if block.id == checkedblock:
                            found = True
                    if found:
                        break
                if found:
                    break
            if not found:
                if debug:
                    print("Chunk unused, deleting...")
                pruned_count += 1
            else:
                if debug:
                    print("Chunk used, saving...")
                region_out.add_chunk(chunk)
    print("Saving region...")
    print("Total original chunks:", chunk_count)
    print("Pruned chunks:", pruned_count)
    print("Saved chunks:", chunk_count - pruned_count)
    print("Output:", out_file)
    print("-----------------------------------------------")
    region_out.save(out_file)


if __name__ == "__main__":    
    in_path = "./region"
    out_path = "./output"
    for file in os.listdir(in_path):
        in_file = os.path.join(in_path, file)
        out_file = os.path.join(out_path, file)
        pruneChunks(in_file, out_file, "glass", fixedcoord=([0,15], [255,255], [0,15]), debug=False)