ResistorCalc.py

import math

res_val = 19872
approx_list = []
parallel = lambda r1, r2: float(r1 * r2) / float(r1 + r2)

for sig in range(0, 4):
    if len(approx_list) > 0:
        pass
    else:
        for r1 in stockroom[len(stockroom) / 2:]:
            for r2 in stockroom:
                if math.trunc(parallel(r1, r2) / (10**sig)) == math.trunc(float(res_val) / (10**sig)):
                    if (r2, r1, parallel(r1, r2)) not in approx_list:
                        approx_list.append((r1, r2, parallel(r1, r2)))

for r1, r2, req in approx_list:
    print '\t'.join([str(r1), str(r2), str(req)])