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1. BASE2 = "01"

2. BASE10 = "0123456789"

3. BASE16 = "0123456789ABCDEF"

4. BASE62 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz"

6. def baseconvert(number,fromdigits,todigits):

7. """ converts a "number" between two bases of arbitrary digits

9.    The input number is assumed to be a string of digits from the

10.    fromdigits string (which is in order of smallest to largest

11.    digit). The return value is a string of elements from todigits

12.    (ordered in the same way). The input and output bases are

13.    determined from the lengths of the digit strings. Negative

14.    signs are passed through.

16.    decimal to binary

17.    >>> baseconvert(555,BASE10,BASE2)

18.    '1000101011'

20.    binary to decimal

21.    >>> baseconvert('1000101011',BASE2,BASE10)

22.    '555'

24.    integer interpreted as binary and converted to decimal (!)

25.    >>> baseconvert(1000101011,BASE2,BASE10)

26.    '555'

28.    base10 to base4

29.    >>> baseconvert(99,BASE10,"0123")

30.    '1203'

32.    base4 to base5 (with alphabetic digits)

33.    >>> baseconvert(1203,"0123","abcde")

34.    'dee'

36.    base5, alpha digits back to base 10

37.    >>> baseconvert('dee',"abcde",BASE10)

38.    '99'

40.    decimal to a base that uses A-Z0-9a-z for its digits

41.    >>> baseconvert(257938572394L,BASE10,BASE62)

42.    'E78Lxik'

44.    ..convert back

45.    >>> baseconvert('E78Lxik',BASE62,BASE10)

46.    '257938572394'

48.    binary to a base with words for digits (the function cannot convert this back)

49.    >>> baseconvert('1101',BASE2,('Zero','One'))

50.    'OneOneZeroOne'

52.    """

54. if str(number)[0]=='-':

55. number = str(number)[1:]

56. neg=1

57. else:

58. neg=0

60. # make an integer out of the number

61. x=0

62. for digit in str(number):

63. x = x*len(fromdigits) + fromdigits.index(digit)

65. # create the result in base 'len(todigits)'

66. if x == 0:

67. res = todigits[0]

68. else:

69. res=""

70. while x>0:

71. digit = x % len(todigits)

72. res = todigits[digit] + res

73. x = int(x / len(todigits))

74. if neg:

75. res = "-"+res

77. return res