Most Efficient Implementation of Spreadsheet Data
I do a lot of work with very large spreadsheet data (most of which is numeric data). I have been using nested lists to work with the data, accessing attributes by their index. I have recently been told that this is not a very efficient way to work with this type of data.

I am curious if there is a more efficient way of structuring this type of data using Dictionaries. 

For instance, if I have a spreadsheet that would normally look like this as nested lists:

    sheet = [['ACCOUNT', 'VALUE1', 'VALUE2', 'VALUE3'],
            ['Account1', '3.4332', '2.524', '4,567.23'],
            ['Account2', '1,235.67', '8.98', 4,321.78']]

How could I set this up using (nested?)Dictionaries so that I can access values by an "Account" key and a "Header" key? (basically easily access Account1, Value2)

I'd prefer the implementation to be efficient from a performance standpoint when iterating over accounts and extracting account/value pairs to compare/mutate. (I do lots of analysis on arrays from one day to the next, where the array structure remains the same, but the numeric data changes).

Most Efficient Implementation of Spreadsheet Data
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I do a lot of work with very large spreadsheet data (most of which is numeric data). I have been using nested lists to work with the data, accessing attributes by their index. I have recently been told that this is not a very efficient way to work with this type of data.

I am curious if there is a more efficient way of structuring this type of data using Dictionaries. 

For instance, if I have a spreadsheet that would normally look like this as nested lists:

    sheet = [['ACCOUNT', 'VALUE1', 'VALUE2', 'VALUE3'],
            ['Account1', '3.4332', '2.524', '4,567.23'],
            ['Account2', '1,235.67', '8.98', 4,321.78']]

How could I set this up using (nested?)Dictionaries so that I can access values by an "Account" key and a "Header" key? (basically easily access Account1, Value2)

I'd prefer the implementation to be efficient from a performance standpoint when iterating over accounts and extracting account/value pairs to compare/mutate. (I do lots of analysis on arrays from one day to the next, where the array structure remains the same, but the numeric data changes).
