[Tutor] How to store key->multiple values?

[Michael Janssen]

On Tue, 30 Dec 2003, Kenneth Gomez wrote:

> I would like some advice on how to store data of these types :
>
> Material Name		Young's Modulus	Poisson's Ratio		Density
> Aluminum		200e5			.27			2700
> Steel			200e9			.33			8020
>
> I would like this to be in an array where I can access the first subscript
> and get the rest of the values.
>
> I thought of using a dictionary but I found that dictionary only allows one
> value per key. Can I use lists instead? How do I create a multidimensional
> list or tuple? How would I insert the values into a multidimensional list?

Lists and dictionaries can easily nest (Just another one of python's
strengths?). To do it store another list/dict as the value:

>>> d = {}
>>> d["Aluminum"] = {"Young's Modulus": 200e5,
...                  "Poisson's Ratio": .27,
...                  "Density": 2700,
...                 }
>>> d["Aluminum"]["Density"]
2700

perhaps it's easier to store the second level into a list (values are
then identified by list-index, eg d["Aluminum"][2] always shows
Density).

When your data gets more and more complicated, you might want to see how
it looks pretty:
>>> import pprint
>>> pprint.pprint(d)
[snip: pretty printed representation of d]


Michael