Python：如何遍历两个列表，一个用于键，一个用于值，并将其放入新的空字典中？

Question

Here is the data I have I want to loop over the two lists the symbol list as the key and symbol_name as the value how do I do it with using the loop

calculator_dict = {}   # the new dictionary i want to put both the list into

symbols = ["+", "-", "*", "/"]

symbol_name = ["add", "subtract", "multiply", "divide"]

for symbol in symbols:

  for name in symbol_name:

    calculator_dict[symbol] = name

print(calculator_dict)

What i want to be printed is:

calculator_dict = {
    "+": "add",
    "-": "subtract",
    "*": "multiply",
    "/": "divide",
}

Answer 1

Use the zip and dict functions:

>>> symbols = ["+", "-", "*", "/"]
>>> symbol_name = ["add", "subtract", "multiply", "divide"]
>>> dict(zip(symbols, symbol_name))
{'+': 'add', '-': 'subtract', '*': 'multiply', '/': 'divide'}

Answer 2

You can also use a dict comprehension over the zipped lists:

>>> symbols = ["+", "-", "*", "/"]
>>> symbol_name = ["add", "subtract", "multiply", "divide"]
>>> calculator_dict = { s:n for s,n in zip(symbols, symbol_name) }
{'+': 'add', '-': 'subtract', '*': 'multiply', '/': 'divide'}

This is useful if you need more fine-grained control.

For example, uppercase the values:

>>> { s:n.capitalize() for s,n in zip(symbols, symbol_name) }
{'+': 'ADD', '-': 'SUBTRACT', '*': 'MULTIPLY', '/': 'DIVIDE'}

Or filter values by length:

>>> { s:n for s,n in zip(symbols, symbol_name) if len(n) < 5 }
{'+': 'add'}