如何根据键从字典中检索值？

Question

I am stuck at this minor problem for quite some time and cannot understand why.

Let's say I have a list :

test = ['1', '2', '3']

I convert this into dictionary using

test_dict =  { i : test[i] for i in range(0, len(test))}

{0: '1', 1: '2', 2: '3'}

Now when I access key based on value like this

print (a.get('1')) 

it gives me None. Any suggestions in this regard would be helpful.

Answer 1

Its a problem of type

test_dict =  { i : test[i] for i in range(0, len(test))}

{0: '1', 1: '2', 2: '3'}

The keys will be of integer type and not string type.

Try this out instead

print (a.get(1))

Edit: To get the keys, you can flip the dictionary creation

test_dict =  { test[i] : i for i in range(0, len(test))}

print (a.get(1))
0