#key value pairs

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Day 3 of Learning Python: dictionaries

Day 3 of Learning Python: dictionaries

Photo by Jen Theodore on Unsplash

Today I learned about dictionaries. Dictionaries are a collection of key-value pairs.  Think JSON, AWS tags and MongoDB. The key and value go together and the data inside the dictionary can be accessed via the key. The indexes aren’t accessed via their numerical, zero based index, they are accessed via their named indexes since there is no real ‘order’ to the…

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Retrieving Values from Hashes

In Ruby, there are at least two ways to get a specific value from a hash with two different results if the key is not found.

1. Hash#fetch

h = { "a" => 100, "b" => 200 } h.fetch("z") => KeyError: key not found: "z"from (pry):26:in `fetch'

2. hsh[key] → value

h = { "a" => 100, "b" => 200 } h["z"] => nil

Which one you want to use depends on whether you want to raise an error if it doesn't exist or just check if it is nil.