pythonで62進数から10進数への変換：a → 10, Z → 61

Question

62進数4桁の値を上2桁（Xとする）と下2桁（Yとする）
に分解し、(Xの10進数表記, Yの10進数表記)での形式で出力するよう書きたいです。
※62進数から10進数への変換：a → 10, Z → 61
※62進数2桁の場合、62の0乗の位と62の1乗の位で構成される。
※出力例）a50Y → (625, 60)

以下プログラムを書いてみましたが出力がうまくいきませんでした。

何かわかる方いましたら教えてください

test = ["0","1","2","3","4","5","6","7","8","9",
  "a","b","c","d","e","f","g","h","i","j","k","l","m","n",
  "o","p","q","r","s","t","u","v","w","x","y","z","A","B",
  "C","D","E","F","G","H","I","J","K","L","M","N","O","P",
  "Q","R","S","T","U","V","W","X","Y","Z"]



for XZA in test:
    for XZA2 in test:
        for XZA3 in test:
            for XZA4 in test:
                x = XZA*62+XZA2
                y = XZA3*62+XZA4
                print(XZA+XZA2+XZA3+XZA4+"("+x+","+y+")")

Answer 1

s = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
def g(x): return s.index(x[0]) * 62 + s.index(x[1])
def f(x): return g(x[:2]), g(x[2:])

a = "a50Y"
x, y = f(a)
print(a, " → (", x, ",", y, ")", sep="")

関数名などは適当に変更してください。

Answer 2

インデックスを取得してから掛け算してください。

                x = test.index(XZA)*62+test.index(XZA2)
                y = test.index(XZA3)*62+test.index(XZA4)
                print(XZA+XZA2+XZA3+XZA4+"("+str(x)+","+str(y)+")")

Answer 3

for文はもっと簡単に書けます。
for c in value: sum = sum * 62 + s.index(c)

すみません。
shiketa さんへのコメントのつもりが間違って新規回答になってしまいました。
なぜか、回答を削除できません。

Comments

[shiketa]

なるほど。ご指摘を参考にしてreduceしてみました。勉強になりました。

``
from functools import reduce
s = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
def radix62(value): return reduce(lambda a, b: a * len(s) + s.index(b), value, 0)
```

Answer 4

何桁でもいけるように、オーバースペックで...

def radix62(value):
    s = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    sum = 0
    for (c, index) in zip(value, reversed(range(len(value)))):
        sum += s.index(c) * pow(len(s), index)
    return sum

for text in ['0', '1', '9', 'a', 'b', 'y', 'z', 'A', 'B', 'Y', 'Z', '10', '19', '1a', '1z', \
    '1A', '1Z', '20', '21', 'ZY', 'ZZ', '100', '101', 'a5', '0Y']:
    print("'%s' = %s" % (text, radix62(text)))

#
input = "a50Y"

print("(%s, %s)" % (input[:2], input[2:]))
print("(%s, %s)" % (radix62(input[:2]), radix62(input[2:])))

# '0' = 0
# '1' = 1
# '9' = 9
# 'a' = 10
# 'b' = 11
# 'y' = 34
# 'z' = 35
# 'A' = 36
# 'B' = 37
# 'Y' = 60
# 'Z' = 61
# '10' = 62
# '19' = 71
# '1a' = 72
# '1z' = 97
# '1A' = 98
# '1Z' = 123
# '20' = 124
# '21' = 125
# 'ZY' = 3842
# 'ZZ' = 3843
# '100' = 3844
# '101' = 3845
# 'a5' = 625
# '0Y' = 60
# (a5, 0Y)
# (625, 60)