Header to read 16-bit MRC files

myheader.py

#!/usr/bin/env python
import sys
import struct

with open(sys.argv[1], "rb") as f:
    [nx, ny, nz] = [x[0] for x in struct.iter_unpack('i', f.read(12))]

    # don't care about mode, start
    _ = f.read(16)

    [mx] = struct.unpack('i', f.read(4))
    _ = f.read(8)
    [xlen] = struct.unpack('f', f.read(4))
    _ = f.read(8)
    apix = round(xlen / mx, 4)

    # don't care about cell angles or mapping
    _ = f.read(24)

    [amin] = struct.unpack('f', f.read(4))
    [amax] = struct.unpack('f', f.read(4))
    [amean] = struct.unpack('f', f.read(4))

    amin = round(amin, 3)
    amax = round(amax, 3)
    amean = round(amean, 3)

print()
print("Width\t", f"{ny:.>30}", sep = "")
print("Height\t", f"{nx:.>30}", sep = "")
print("Frames\t", f"{nz:.>30}", sep = "")
print()
print("A/pix\t", f"{apix:.>30}", sep = "")
print()
print("Min\t", f"{amin:.>30}", sep = "")
print("Mean\t", f"{amean:.>30}", sep = "")
print("Max\t", f"{amax:.>30}", sep = "")