"""記事 invoice-tax-rounding-monthly の計算(商いの帳場)。python scripts/figs/invoice_tax_rounding.py で再現できる。
架空の1か月分の納品データ(top_numbers.py の 3 と同じ乱数の種・同じ作り方)で、消費税額を3通りに計算する。
A 明細ごとに端数処理して合計(国税庁 Q&A 問57 の注で認められない方法。比べるためだけに計算)
B 納品書ごとに税率ごとに1回(問67:納品書に税率ごとの消費税額等を書き、納品書と請求書で適格請求書にする場合)
C 月まとめの請求書で税率ごとに1回(問65:請求書を適格請求書にする場合)
金額はすべて税抜、税率は8%と10%。端数処理は切り捨て・四捨五入・切り上げの3つで計算する。外部のデータは使わない。
出力:標準出力に JSON、public/img/articles/invoice-tax-rounding-monthly-{3ways,decide,lost}.svg(図1〜3)。
"""
import json, random, math, pathlib, sys
sys.stdout.reconfigure(encoding='utf-8')
from decimal import Decimal, ROUND_HALF_UP
DECIDE = """"""
ROOT = pathlib.Path(__file__).resolve().parents[2]
rng = random.Random(20261016)
deliveries = []
for i in range(20):
lines = []
for _ in range(rng.randint(2, 6)):
rate = 8 if rng.random() < 0.7 else 10
price = rng.choice([128, 198, 248, 356, 480, 615, 742, 980, 1260, 1580, 2380, 3150])
qty = rng.randint(1, 24)
lines.append((rate, price * qty))
deliveries.append(lines)
def rnd(x100, mode): # x100 = 金額×税率(整数)。税額 = x100/100 の端数処理
q = Decimal(x100) / 100
if mode == 'floor': return math.floor(q)
if mode == 'ceil': return math.ceil(q)
return int(q.quantize(Decimal('1'), rounding=ROUND_HALF_UP))
out = {'seed': 20261016, 'deliveries': len(deliveries), 'lines': sum(len(l) for l in deliveries)}
base = {8: 0, 10: 0}
for l in deliveries:
for r, a in l: base[r] += a
out['base'] = base
out['linesByRate'] = {r: sum(1 for l in deliveries for x in l if x[0] == r) for r in (8, 10)}
out['deliveriesWithBoth'] = sum(1 for l in deliveries if {x[0] for x in l} == {8, 10})
out['roundingUnits'] = {'A': out['lines'], 'B': sum(len({x[0] for x in l}) for l in deliveries), 'C': 2}
res = {}
for mode in ('floor', 'half_up', 'ceil'):
A = {r: sum(rnd(a * r, mode) for l in deliveries for rr, a in l if rr == r) for r in (8, 10)}
B = {8: 0, 10: 0}
for l in deliveries:
s = {8: 0, 10: 0}
for r, a in l: s[r] += a
for r in (8, 10):
if s[r]: B[r] += rnd(s[r] * r, mode)
C = {r: rnd(base[r] * r, mode) for r in (8, 10)}
res[mode] = {k: {'8': v[8], '10': v[10], 'total': v[8] + v[10]} for k, v in (('A', A), ('B', B), ('C', C))}
res[mode]['exact'] = {r: str(Decimal(base[r] * r) / 100) for r in (8, 10)}
out['results'] = res
# 納品書ごとの切り捨てで消えた端数(円未満)の分布
lost = []
for l in deliveries:
s = {8: 0, 10: 0}
for r, a in l: s[r] += a
lost.append(round(sum((s[r] * r % 100) / 100 for r in (8, 10)), 2))
out['lostPerDelivery'] = lost
print(json.dumps(out, ensure_ascii=False, indent=1))
# 図:3通りの税額(切り捨て)
f = res['floor']; vals = [('明細ごと(不可)', f['A']['total'], '#a8a8a8', '#444444'), ('納品書ごと(問67)', f['B']['total'], '#b5cc8e', '#111111'), ('請求書で1回(問65)', f['C']['total'], '#678b2c', '#ffffff')]
W, H = 720, 300; x0, x1 = 210, 640; lo = min(v[1] for v in vals) - 60; hi = max(v[1] for v in vals) + 10
def X(v): return x0 + (v - lo) / (hi - lo) * (x1 - x0)
font = "'Hiragino Sans','Yu Gothic','Meiryo',sans-serif"
s = [f"")
p = ROOT / 'public/img/articles'; p.mkdir(parents=True, exist_ok=True)
(p / 'invoice-tax-rounding-monthly-3ways.svg').write_text(''.join(s), encoding='utf-8')
# 図2(判定図)と図3(消えた端数)。public/img/articles/ に書き出す
if True:
# 図2 納品書ごとに切り捨てで消えた円未満の端数
W, H = 720, 280; bx, bw, by, bh = 60, 24, 60, 150; mx = 1.4
t = [f"")
(p / 'invoice-tax-rounding-monthly-lost.svg').write_text(''.join(t), encoding='utf-8')
# 判定図は国税庁 Q&A 問57・65・67 の読みを手で描いたもの(金額は上の計算値)
(p / 'invoice-tax-rounding-monthly-decide.svg').write_text(DECIDE, encoding='utf-8')