michaeldehaan.net

I was looking for a simple way to diff two complex hashes. In order to make the output nicely readable for humans, I’d first like to flatten the hashes. For example:

test = { 
         "a" : [ "dog", "cat", "chicken" ],
         "b" : {
             "c" : 0,
             "d" : [ "red", "yellow", "blue" ],
         },
         "e" : "shiny"
   }

Becomes:

{   
    'a': ['dog', 'cat', 'chicken'], 
    'b.c': 0, 
    'b.d': ['red', 'yellow', 'blue'],
    'e': 'shiny', 
}

Here is a very long Perl module that does this. Here’s my cut:

  def _flatten_ds(self, ds, result=None, memo=""):
        if result is None:
            result = {}
        assert type(ds) == type({})
        for (k,v) in ds.iteritems():
                if memo == "":
                    new_memo = k
                else:
                    new_memo = "%s.%s" % (memo,k)
                if type(v) == type({}):
                    self._flatten_ds(v, result=result, memo=new_memo)
                else:
                    result[new_memo] = v
        return result

Almost 300 lines shorter than the Perl module