Decoding in Ruby using base64

Question

How I can decode the following binary 64 bit float?

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

Using the Base64.decode64('insert above binary data here') returns this following mess

�F�pHf�FnHP�G:�G�3GdW�F��G1��FyG� JG�>GnJ�F[o�G�vG��G�^;H�k ��F�B�F0� G��F��F�`?G��Ge��GL��F})�F�S�F�A�F"A�F��F3�F�F�C�Ft:G�QG �Fx܊F.iG�׭Fl�F44qGgɰF��MGuP�H/�#G��FU �G*�Fa��F

I need to decode it to a list of floats like this 27489.1602 57338.4453 45343.3516 91321.0391 43205.043 and so on....

Thank you for your help!

I think more information is needed to decode the string. The byte order is unknown, nor is the byte length. Once the string is decoded - I used s.unpack('m*')[0] - the unpacking of the string requires more information. For example, s.unpack('m*')[0].unpack('d*') is different than s.unpack('m*')[0].unpack('f*') ... Please provide more information. — Myst
– Myst, Commented May 5, 2015 at 6:59
64bit float, 1824 is encodedLength, no compression... I don't know what you are asking for but this is all the information I have to decode it. — Ayechan_San
– Ayechan_San, Commented May 5, 2015 at 7:32
s.unpack('m*')[0] decodes the Base64 (it's the same as Base64.decode64(s)), but now we have a string we want to #unpack, converting the bit sequence into new objects. The bit sequence holds 1368 bytes (once Base64 was decoded), which packs 171 64bit sequences.... I think maybe this is what you are looking for: s.unpack('m*')[0].unpack('d*') ... only I don't get the values in your example, so I must be wrong. — Myst
– Myst, Commented May 5, 2015 at 8:10

Myst · Accepted Answer · 2015-05-05 08:12:30Z

3

You can use s.unpack('m*')[0] to decode the Base64 string.

it's the same as: Base64.decode64(s)

Now we have a string we want to #unpack, converting the bit sequence into new objects.

The bit sequence holds 1368 bytes (once Base64 was decoded), which packs 171 64bit sequences.... I think maybe this is what you are looking for:

s.unpack('m*')[0].unpack('d*')
# => [595.6329345703125, 596.281005859375, 596.529296875, ... ]

... only I don't get the values in your example, so I must be wrong.

answered May 5, 2015 at 8:12

Myst

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