如何在字典中查找特定值并正确返回它们答案

【问题标题】：How to look for specific values in a dictionary and return them properly如何在字典中查找特定值并正确返回它们
【发布时间】：2021-07-22 22:02:24
【问题描述】：

所以我有一个字典列表字典 (lst)，我试图对其进行迭代、比较值并返回适当的值。

我有以下代码来检索从命令行给出的 2 个参数，通过字典条目比较它们，并返回适当的值：

def get_attribute_number(cmd1, cmd2, lst):

    app_name = cmd1
    attribute = cmd2
    for name in lst: #lst is a dictionary
        if name["description"] == app_name:
            print(int(name[attribute]))

get_attribute_number(cmd1=sys.argv[1], cmd2=sys.argv[2], lst=data_list)

但是，我的程序没有返回任何内容。例如，如果我提供 cmd 行参数 python3 program.py [NAME] [ATTRIBUTE]，则应该查询上述数据，直到找到名称的匹配项，并将其请求的属性作为整数返回。任何人都可以就我为什么不能print(int(name[attribute])) 提供相应的napp_name 提供建议吗？

【问题讨论】：

"['kytos/kytos']" 不等于 "kytos/kytos"
@jakubDóka 即使我将它 (str()) 转换为字符串也没有任何反应。关于如何将“['kytos/kytos']”转换为字符串的任何建议？

标签： python dictionary parsing iteration dictionary-comprehension

【解决方案1】：

为了对用户更友好，我稍微修改了你的代码：

import sys

data_list = [{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/kytos']", '{#PASSED}': '316', '{#FAILED}': '1', '{#WARNING}': '204', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/python-openflow']", '{#PASSED}': '400', '{#FAILED}': 0, '{#WARNING}': 0, '{#SKIPPED}': '40', '{#XFAILED}': '1'},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/of_core']", '{#PASSED}': '49', '{#FAILED}': 0, '{#WARNING}': '39', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/kytos-utils']", '{#PASSED}': '102', '{#FAILED}': '2', '{#WARNING}': 0, '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/mef_eline']", '{#PASSED}': '102', '{#FAILED}': 0, '{#WARNING}': '88', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/flow_manager']", '{#PASSED}': '36', '{#FAILED}': 0, '{#WARNING}': '22', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/topology']", '{#PASSED}': '58', '{#FAILED}': 0, '{#WARNING}': '56', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/kronos']", '{#PASSED}': '61', '{#FAILED}': 0, '{#WARNING}': '21', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/pathfinder']", '{#PASSED}': 0, '{#FAILED}': 0, '{#WARNING}': 0, '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/status']", '{#PASSED}': '81', '{#FAILED}': 0, '{#WARNING}': '1', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/of_l2ls']", '{#PASSED}': '7', '{#FAILED}': 0, '{#WARNING}': '7', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/of_lldp']", '{#PASSED}': '17', '{#FAILED}': 0, '{#WARNING}': '17', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['success']", '{#DESCRIPTION}': "['kytos/maintenance']", '{#PASSED}': '28', '{#FAILED}': 0, '{#WARNING}': '28', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/storehouse']", '{#PASSED}': '63', '{#FAILED}': '1', '{#WARNING}': '32', '{#SKIPPED}': 0, '{#XFAILED}': 0},
{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/kytos-end-to-end-tester']", '{#PASSED}': 0, '{#FAILED}': 0, '{#WARNING}': 0, '{#SKIPPED}': 0, '{#XFAILED}': 0}]

def get_attribute_number(cmd1, cmd2, lst):
    """For each attribute under a napp, retrieve that attribute as a NUMBER"""
    napp_name = cmd1
    attribute_name = cmd2
    for napp in lst: #lst is a dictionary
        if napp_name in napp["{#DESCRIPTION}"]: # change happened here
            print(napp)
            print(int(napp[attribute_name]))

get_attribute_number(sys.argv[1], sys.argv[2], data_list)

基本上只需要输入子字符串就可以得到一些结果，所以这个：

python tt.py 'kytos/kytos' {#SKIPPED}

只输出所需的数据：

{'{#Status}': "['failed']", '{#DESCRIPTION}': "['kytos/kytos']", '{#PASSED}': '316', '{#FAILED}': '1', '{#WARNING}': '204', '{#SKIPPED}': 0, '{#XFAILED}': 0}
0

【讨论】：

【解决方案2】：

要回答有关转换为字符串的问题：您可以尝试评估将为您提供列表的表达式；如果格式始终相同，您也可以使用正则表达式：

import ast
ast.literal_eval(napp["{#DESCRIPTION}"])[0]

所以在你的情况下：

import ast
def get_attribute_number(cmd1, cmd2, lst):
    """For each attribute under a napp, retrieve that attribute as a NUMBER"""
    napp_name = cmd1
    attribute_name = cmd2
    for napp in lst: #lst is a dictionary
        if ast.literal_eval(napp["{#DESCRIPTION}"])[0] == napp_name:
            print(int(napp[attribute_name]))

【讨论】：