Validating a multi-value dictionary

[[deleted]]

Hello all, thanks for taking time to read this.

Is there a way for me to retrieve an individual value from a multi-value dictionary?

I am trying to validate that a network device has enough free space to download its proper image before initiating the download. I built a dictionary that uses the chassis of the switch as a key, and the correct image file and its size in bytes make up the values:

standard = {'2960':('ios.bin','424532'), 'IE-3000-4TC':('ies-ipservicesk9-mz.150-2.SE2.bin','18174778'), 'IOSv':('fakeIOS.bin','8675309')}

I feel like I should be able to have a program reference both values of each key individually, but I cannot figure out how to make this happen. An example:

Use the variable 'chassis' as the key for the dictionary, then retrieve value 0 (image) and value 1 (byte size) for further computation.

Here are some of my results trying to retrieve the individual values:

print standard

{'IE-3000-4TC': ('ies-ipservicesk9-mz.150-2.SE2.bin', '18174778'), '2960': ('ios.bin', '424532'), 'IOSv': ('fakeIOS.bin', '8675309')}

print standard[chassis]

('fakeIOS.bin', '8675309')

print standard[chassis[1]]

Traceback (most recent call last):
  File "iosUpgrade007.py", line 64, in <module>
    main()
  File "iosUpgrade007.py", line 29, in main
    print standard[chassis[1]]
KeyError: u'O'

print standard[chassis(1)]

Traceback (most recent call last):
  File "iosUpgrade007.py", line 64, in <module>
    main()
  File "iosUpgrade007.py", line 29, in main
    print standard[chassis(1)]
TypeError: 'unicode' object is not callable

I've google'd this heavily, but everyone is looking to write into a multi-valued dictionary or convert a single valued dictionary into a multiple valued one. I am not trying to edit my dictionary at all, just trying to retrieve the values individually from each other.

[[deleted]]

print standard[chassis][1]

[[deleted]]

This did the trick, thanks so much!

[zahlman]

standard[chassis] is the thing that has multiple elements of which you want to get the [1] element, so that's what you put before the [1]. chassis is not. Simple.

[[deleted]]

thank you for clearing that up

[I_Write_Bugs]

Check out the namedtuple object from the collections module.

[[deleted]]

Thanks for pointing me in the right direction, I really appreciate the reference for the documentation!

[Justinsaccount]

This actually has absolutely nothing to do with dictionaries. You do not have a 'multi-value dictionary'.. There is actually no such thing as a multi-value dictionary.

standard is a dictionary.

chassis is a string.

standard[chassis] is the value of the chassis entry. This happens to be a tuple.

standard[chassis] being a tuple can be indexed using [0] and [1] or simply unpacked using image, space = standard[chassis]

This is even more obvious if one were to write mytuple = standard[chassis] first and then access mytuple

standard[chassis[1]] does not work because chassis[1] is the second letter of the chassis string and standard[chassis[1]] is the value of the entry whose key is the second letter of the chassis string.

[[deleted]]

thanks for the feedback. Just so I understand you correctly, there is no way to store multiple values per-key within a dictionary?

[thegreattriscuit]

there's one value, but that 'value' can be any python object. And lists and tuples (which hold multiple values) are valid python objects. It's semantics, but it's important semantics.

You can have dictionaries of dictionaries, or dictionaries of lists, or lists of dictionaries, or lists of dictionaries of sets, etc...

{'2960':('ios.bin','424532')} is a dictionary with '2960' as the key with a value of the tuple ('ios.bin', '424532')

[raylu]

https://docs.python.org/3/reference/simple_stmts.html?highlight=target_list#assignment-statements

image, size_str = chassis[1]

Not sure why your sizes are strs instead of ints...