如何从文本文件中读取字典？

Question

I have a text file in the below format

d = {'EMS':1,'ESC': 2, 'HVAC': 3,'IC' : 4,'ICU' : 5,'IS' : 6,'ITM' : 7,'MBFM' : 8,'PKE' : 9,'RPAS' : 10,'RVC' : 11,'SAS' : 12,'SRS' : 13,'TCU' : 14,'TPMS' : 15,'VCU' : 16,'BMS' : 17,'MCU' :18,'OBC' :19}

How do I read the dictionary to find the value a particular value?

I have tried the below code

with open(r"filename","r") as f:
    data = ast.literal_eval(f.read())
    print(data)
    for age in data.values():
        if age == search_age:
            name = data[age]
            print (name)

Answer 1

Your text file is a valid Python code, so if it is from a trusted source, you can simply do:

with open("filename") as f:
    exec(f.read())

and the variable d would be loaded with the dict.

If the text file is not from a trusted source, however, you can use ast.parse to parse the code, then use ast.walk to traverse the abstract syntax tree and look for a Dict node. For security reasons, make sure the dict node does not contain any Call node before wrapping it as the body of an Expression node and compiling it for eval to turn it into a real dict stored in variable d :

import ast
with open("filename") as f:
    for node in ast.walk(ast.parse(f.read())):
        if isinstance(node, ast.Dict) and \
                not any(isinstance(child, ast.Call) for child in ast.walk(node)):
            d = eval(compile(ast.Expression(body=node), '', 'eval'))
            break
    else:
        print('No valid dict found.')

Given your sample input, d would become:

{'EMS': 1, 'ESC': 2, 'HVAC': 3, 'IC': 4, 'ICU': 5, 'IS': 6, 'ITM': 7, 'MBFM': 8, 'PKE': 9, 'RPAS': 10, 'RVC': 11, 'SAS': 12, 'SRS': 13, 'TCU': 14, 'TPMS': 15, 'VCU': 16, 'BMS': 17, 'MCU': 18, 'OBC': 19}

Answer 2

You need to iterate over both the keys and values:

with open('filename') as f:
    data = ast.literal_eval(f.read())
    print(data)
    for name, age in data.items():
        if age == search_age:
            print(name)

Also, that file looks like a valid JSON object, so you should probably use json.load over ast.literal_eval .