CODEWITHSUNDEEP
python
Steve
Steve

Reputation: 29

Extract a specific element from 3-tuple in dictionary

Given a dictionary:

self.mapping = {}  # key= IP, value = (mac,id,port)

Where the value is 3-tuple values. If I know the key, how do I get a specific element from the 3-tuple? For instance, I want to get id that corresponds to given IP.

Thank you.

Upvotes: 2

Views: 458

Answers (4)

mvelay
mvelay

Reputation: 1520

You could use get() method to properly unpack data from your dict in a pythonic way:

mac_addr, c_id, port = self.mapping.get('192.168.1.1', (None, None, None))

It avoids KeyError exception to be raised in case current IP is not in your dict.

If you only want to extract id field:

_, c_id, _ = self.mapping.get('192.168.1.1', (None, None, None))

Upvotes: 1

justsostephen
justsostephen

Reputation: 21

Python dictionaries and tuples are referenced using bracket notation. Dictionary values are referenced using corresponding keys; items in a tuple are referenced by index, using zero-based numbering (i.e. the first item in a tuple has the index 0, the second 1, and so on).

In your case, you can reference dictionary values using IP address keys:

self.mapping['IP address']

You can reference tuple items using indices:

my_tuple[1]

By combining the two, you can reference a specific item in a dictionary value tuple. In your example, ID is the second value at index 1, so you would use:

self.mapping['IP address'][1]

Upvotes: 2

ForceBru
ForceBru

Reputation: 44926

First, you get that whole tuple:

self.mapping["192.168.1.1"]

Then you just get the second element:

 self.mapping["192.168.1.1"][1]

Upvotes: 0

xiº
xiº

Reputation: 4687

You need to use basic python sequences indexing. According to your sample:

self.mapping['some IP'][1]

Check documentation out.

Upvotes: 0

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