Expandable 2D Dictionaries?

[Jean-Paul Calderone]

On Fri, 06 Jul 2007 15:43:55 -0000, Robert Dailey <rcdailey at gmail.com> wrote:
>Hi,
>
>I am interested in creating an expandable (dynamic) 2D dictionary. For
>example:
>
>myvar["cat"]["paw"] = "Some String"
>
>The above example assumes "myvar" is declared. In order for this to
>work, I have to know ahead of time the contents of the dictionary. For
>the above to work, my declaration must look like:
>
>myvar = {"cat": {"paw":""} }
>
>I would like to not have to declare my dictionary like this, as it
>does not allow it to be expandable. I'm very new to Python (I'm a
>professional C++ programmer. Any comparisons to C++ would help me
>understand concepts).
>
>Is there a way that when I index into my dictionary using an "unknown"
>index (string), that python will dynamically add that key/value pair?

This gets much easier if you change your structure around a bit:

    d = {}
    d["cat", "paw"] = "some string"

Jean-Paul