json char with too many decimals, need removal

I got some json str = '{"hund": 0.3253533250000000000000000000000000, "kat": "dfsdfs", "baenkebider": 0.002021203321320000000000000000000000}';

In reality its a longer string with even more figures. I need to remove all those long decimals. 7-8 decimals is enough, so I end up with something like:

str = '{"hund": 0.3253533, "kat": "dfsdfs", "baenkebider": 0.0020212}';

If someone can help with an elegant solution I will appreciate it a lot!

Thanks in advance,

-best

mergh

[dpb]

>> split(extractBetween(str,'{','}'),',')
ans =
  3×1 cell array
    {'"hund": 0.3253533250000000000000000000000000'          }
    {' "kat": "dfsdfs"'                                      }
    {' "baenkebider": 0.002021203321320000000000000000000000'}
>> str2double(extractAfter(ans,':'))
ans =
    0.3254
       NaN
    0.0020
>> 

Use join() to put the isfinite pieces back together.

Alternatively, although it is crude, you could just do a string subsitution for some arbitrary number of consecutive zeros with empty or simply pick up the leftmost N characters of the numeric values.

A regular expressions maven could undoubtedly write a very clever pattern, but that isn't me... :)

[Martin]

Thanks for answering. join() and isfinite() is however a bit messy with regards to the cell piece.

[dpb]

I knew Stephen or similar would be along...

You'll note I specifically did NOT say it was elegant... :)

Answer 1

[Stephen23]

str = '{"hund": 0.3253533250000000000000000000000000, "kat": "dfsdfs", "baenkebider": 0.002021203321320000000000000000000000}';

Method one (truncate to 9 characters):

out = regexprep(str,'\d+\.\d+','${$&(1:9)}')

out = '{"hund": 0.3253533, "kat": "dfsdfs", "baenkebider": 0.0020212}'

Method two (seven fractional digits):

fun = @(s)sprintf('%.7f',sscanf(s,'%f'));
out = regexprep(str,'\d+\.\d+','${fun($&)}')

out = '{"hund": 0.3253533, "kat": "dfsdfs", "baenkebider": 0.0020212}'

[Martin]

wow, thanks!

[Rik]

This will of course not work on an arbitrary JSON string, so you need to be careful if you want to do so. You could consider using a custom JSON encoder that allows you to trim trailing 0 in decimal notation.