box_size.py

#!/usr/bin/env python3
import sys
if len(sys.argv) == 1:
    diam = input('Particle diameter (A): ')
    defocus = input('Mean defocus (um): ')
    res = input('Target resolution (A): ')
    ps = input('Pixel size (a/pix): ')
elif len(sys.argv) != 5:
    print('Usage: box-sizer.py {diameter in A} {defocus in um} {resolution in A} {apix in A/pix}')
    sys.exit(1)
else:
    diam, defocus, res, ps = sys.argv[1:5]
try:
    diam = float(diam)
    defocus = abs(float(defocus) * 10**4)
    res = float(res)
except ValueError:
    print('All values must be numbers!')
    sys.exit(2)
    print('Box size suggested by Rosenthal and Henderson JMB 2003:')
    # 0.02 is the approximate wavelength of an electron at 300 kV, in A
bs = diam + 2 * (0.02 * (defocus / res))
print(f'{bs} angstroms. Note: not pixels!')
print(f'{bs/float(ps)} in pixels.')