How do you initialize and index a list of dictionaries in Python?

Question

Currently I have something that looks like this:

   if width < 101:
      column_placement_0[index] = rectangles
   elif width < 201:
      column_placement_1[index] = rectangles
   elif width < 301:
       column_placement_2[index] = rectangles

... and so on.

Instead, I want to be able to just initialize a single columns array which stores dictionaries.

First, I feel that I would initialize an array normally...

columns = []

but then I don't know how I would reference the individual list and dictionary indices maybe something like a 2D array in Java?

columns[index][dict_key] = value

What do I do?

The way you have described it is exactly how you would do it. Did you run into a problem? — Burhan Khalid
– Burhan Khalid, Commented Feb 16, 2016 at 4:43
You're correct, just put the dict key in quotes if you type the name in. Column_placement[index]['key'] — Chris
– Chris, Commented Feb 16, 2016 at 4:44
You only put the dictionary key in quotes if the key is a string. — Burhan Khalid
– Burhan Khalid, Commented Feb 16, 2016 at 4:56
Are you trying to replace column_placement_0 and etc... with the single column list? It appears that 100 possible widths could go into a single column_placement_X ... except it has some index thing that has me puzzled. If two rectangles end up in the same index (is that even possible?) should one overwrite the other? If you wrote a demo script that shows what you are doing it would help. Your fragments and description leave a lot to interpretation. — tdelaney
– tdelaney, Commented Feb 16, 2016 at 5:18
If all you want to do is preallocate the list, you need to decide what you want the default value to be and then do for instance columns = [None] * 1000. — tdelaney
– tdelaney, Commented Feb 16, 2016 at 5:19

whenitrains · Accepted Answer · 2018-06-19 21:12:35Z

7

So although people said my code would work as it was the final solution ended up being:

For initialization:

columns = [{} for i in range(10)]

And to store a value:

columns[i][key] = desired value

I'm kind of surprised that people just downvoted my question. The more Python I do, the more this seems like a pretty common data structure...

edited Jun 19, 2018 at 21:12

answered Feb 21, 2016 at 17:21

whenitrains

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1 Comment

Ed Graham Over a year ago

I'm surprised, too. As of April 2024, this answer is still relevant.

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