如何过滤字典值（在另一个字典中）

Question

我会尽力解释这个问题，所以请为长篇文章道歉。

首先，我在这里有一个API（ http://dev.c0l.in:5984/income_statements/_all_docs ），在这本词典中还有5000个其他词典，我可以通过他们的ID访问（ http://dev.c0l.in ：5984 / income_statements / 30e901a7b7d8e98328dcd77c369b6ad7 ）

到目前为止，我已经创建了一个程序，可以对这些词典进行排序，并且只打印（到csv）与用户输入扇区相关的词典（例如医疗保健）

但是，我希望能够实现过滤器搜索，以便程序只打印高于或低于用户输入值的语句，例如，仅从（用户输入）关闭库存中检索数据，并且仅检索以下公司（<=）a期末股票价值 - 40,000。

我的问题是，我不一定确定如何 。

我理解如何获取用户输入，以及如何访问字典中的字典，但我不知道如何过滤或低于用户输入值。

这是我的代码的副本，任何指针将不胜感激！

import urllib #Imports the url - library module (older the urllib2 but has some useful decodes if needed)
import urllib2 #Imports the Url- Library module (Most recently updated + used)
import csv #Imports the commands that allows for csv writing/reading
import json #Imports the ability to read/use Json data
import time #Imports the time module - allows the developer to examine benchmarks (How long did it take to fetch data)
import os


income_csv = csv.writer(open("Income Statement_ext.csv", "wb")) #This creates a CSV file and writes functions to it
financial_csv = csv.writer(open("Statement of financial position_ext.csv", "wb"))

#The two csv 'writers' create the headers for the information within the CSV file before the information from the api is added to it
financial_csv.writerow([
    ('Company name'),
    ('Non Current Assets'),
    ('Current Assets'),
    ('Equity'),
    ('Non-Current Assets'),
    ('Current Liabilities')])

income_csv.writerow([
    ('Company name'),
    ('Sales'),
    ('Opening Stock'),
    ('Purchases'),
    ('Closing Stock'),
    ('Expenses'),
    ('Interest payable'),
    ('Interest receivable')])

income_url = "http://dev.c0l.in:5984/income_statements/_all_docs"
income_request = urllib2.urlopen(income_url).read()
income_response = json.loads(income_request)
#defines the income url

financial_url = "http://dev.c0l.in:5984/financial_positions/_all_docs"
financial_request = urllib2.urlopen(financial_url).read()
financial_response = json.loads(financial_request)
#defines the financial postion url
count = 0
#sets the count for documents printed to 0
def income_statement_fn():
    global count #allows for the count to be kept globally
    print ("(Type help if you would like to see the available choices)")
    income_user_input = raw_input("Which sector would you like to iterate through in Income Statement?: ").lower()# Asks the user which sector within the chosen statement he/she would like to examine
    if income_user_input == "help":
        print ("Available sectors are: ")
        print ("Technology")
        print ("Healthcare")
        print ("Industrial goods")
        print ("Financial")
        print ("Utilities")
        print ("Basic materials")
        print ("Services") 
        income_statement_fn()

    elif income_user_input == "technology" or income_user_input == "healthcare" or income_user_input == "industrial goods" or income_user_input == "financial" or income_user_input == "utilities" or income_user_input == "basic materials" or income_user_input == "services":
        print 'Starting...' # I use this print to set a milestone (if it prints this, everything before it has worked without error)
        start = time.clock()
        start
        for item in income_response['rows']:
            is_url = "http://dev.c0l.in:5984/income_statements/" + item['id'] #This combines the api with the array's ID's allowing us to access every document automatically
            is_request = urllib2.urlopen(is_url).read() #Opens is_url and reads the data
            is_response = json.loads(is_request) #loads the data in json format
            if is_response.get ('sector') == income_user_input: #matches the sector the user inputed - allows us to access that dictionary
                income_csv.writerow([
                 is_response['company']['name'],
                 is_response['company']['sales'],
                 is_response['company']['opening_stock'],
                 is_response['company']['purchases'],
                 is_response['company']['closing_stock'],
                 is_response['company']['expenses'],
                 is_response['company']['interest_payable'],
                 is_response['company']['interest_receivable']]) # The lines of code above write the chosen fields to the csv file
            count +=1
            print ("filtering statements") + ("( "+" %s "+" )") % count
        start
        print start
        restart_fn()
    else:
        print ("Invalid input!")
        income_statement_fn()





def financial_statement_fn(): # Within this function is the code required to fetch information related to the financial position statement
    global count # Allows for the count to be kept globally (outside the function)
    print ("(Type help if you would like to see the available choices)")
    financial_user_input = raw_input("Which sector would you like to iterate through in financial statements?: ").lower()
    if financial_user_input == "help":
        print ("Available sectors are: ")
        print ("Technology")
        print ("Healthcare")
        print ("Industrial goods")
        print ("Financial")
        print ("Utilities")
        print ("Basic materials")
        print ("Services")
        financial_statement_fn()

    elif financial_user_input == "technology" or financial_user_input == "healthcare" or financial_user_input == "industrial goods" or financial_user_input == "financial" or financial_user_input == "utilities" or financial_user_input == "basic materials" or financial_user_input == "services":
        print 'Starting'
        for item in financial_response['rows']:
            fs_url = "http://dev.c0l.in:5984/financial_positions/" + item['id']#This combines the api with the array's ID's allowing us to access every document automatically
            fs_request = urllib2.urlopen(fs_url).read()
            fs_response = json.loads(fs_request)
            if fs_response.get ('sector') == financial_user_input:
                financial_csv.writerow([
                    fs_response['company']['name'],
                    fs_response['company']['non_current_assets'],
                    fs_response['company']['current_assets'],
                    fs_response['company']['equity'],
                    fs_response['company']['non_current_liabilities'],
                    fs_response['company']['current_liabilities']])
                count +=1
                print ("printing statements") + ("( "+" %s "+" )") % count
        print ("---------------------------------------------------------------------")
        print ("finished fetching data")
        print ("---------------------------------------------------------------------")
        restart_fn()

    else:
        print ("Invalid Input!")
        financial_statement_fn()


def launch_fn():
    print ("Please type 'help' if you would like to examine all available options")
    launch_user_input = raw_input("Welcome, Which statement would you like to examine?: ").lower()
    if launch_user_input == "income" or launch_user_input == "income statement":
        income_statement_fn()
    elif launch_user_input == "financial" or launch_user_input == "financial statement":
        financial_statement_fn()
    elif launch_user_input == "help" :
        print ("You can use the following commands on this menu: ")
        print ("---------------------------------------------------------------------")
        print ("Income or Income statement")
        print ("Will allow you to retrieve data relating to financial Income statements")
        print ("---------------------------------------------------------------------")
        print ("Financial or Financial statement")
        print ("Will allow you to retrieve data relating to the statement of financial position")
        print ("---------------------------------------------------------------------")
        launch_fn()
    else:
        print ("If you would like to look at the available options please type help")
        launch_fn()

def restart_fn():
    restart_prompt = raw_input("Would you like to examine another statement?: ").lower()
    if restart_prompt == 'y' or restart_prompt == 'yes':
        launch_fn()
        count = 0
    elif restart_prompt == 'n' or restart_prompt == 'no':
        raise SystemExit("Shutting down....")

def restart_api_down_fn():
    print ("Type 'y' or 'yes' to continue, 'n' or 'no' to exit or 'r' or 'reconnect' to test servers again")
    restart_prompt_api = raw_input("Would you like to continue anyway?: ").lower()
    if restart_prompt_api == 'r' or restart_prompt_api == 'reconnect' or restart_prompt_api == 'test':
        api_status_fn()
        count = 0
    elif restart_prompt_api == 'n' or restart_prompt_api == 'no':
        raise SystemExit("Shutting down....")
    elif restart_prompt_api == 'y' or restart_prompt_api == 'yes':
        print (" Continuing... Programme performance may be severely affected")
        launch_fn()
    else:
        print ("Invalid input...")
        restart_api_down_fn()

def api_status_fn():
    hostname_income = "http://dev.c0l.in:5984/income_statements" 
    response_income = os.system("ping -c 1 " + hostname_income)
    hostname_financial = "http://dev.c0l.in:5984/financial_positions"
    response_financial = os.system("ping -c 1 " + hostname_financial)
    global count
    count = 0

    if response_income == 0:
        print hostname_income, 'is up!'
        count +=1
    else:
        print hostname_income, 'is experiencing connection issues!'        

    if response_financial == 0:
        print hostname_financial, 'is up!'
        count +=1

    else:
        print hostname_financial, 'is experiencing connection issues!'

    if count == 2:
        launch_fn()

    elif count == 0:
        restart_api_down_fn() # Code only for UNIX SYSTEMS?

#def api_status_fn():
 #   hostname = "http://dev.c0l.in:5984/income_statements"
  #  ping = urllib.urlopen(hostname).getcode()
   # if ping == "200":
     #   print 'oh no!'
# add filtering & sorting







api_status_fn()

如果您需要任何其他解释，请告诉我们，

干杯!

Answer 1

我会说你的代码很混乱，如果你试图把它分解一下，你可能会有更多的运气。 我会尝试在这个答案结束时提出一些建议。

从根本上说，您需要过滤得到的具体结果。 查看您的代码，我可以看到以下内容：

elif financial_user_input == "technology" or financial_user_input == "healthcare" or financial_user_input == "industrial goods" or financial_user_input == "financial" or financial_user_input == "utilities" or financial_user_input == "basic materials" or financial_user_input == "services":
    print 'Starting'
    for item in financial_response['rows']:
        fs_url = "http://dev.c0l.in:5984/financial_positions/" + item['id']#This combines the api with the array's ID's allowing us to access every document automatically
        fs_request = urllib2.urlopen(fs_url).read()
        fs_response = json.loads(fs_request)
        if fs_response.get ('sector') == financial_user_input:

此代码混合了以下职责：

• 验证用户输入
• 请求记录
• 过滤记录

如果您将这些职责分解为单独的方法，那么您会发现您的代码更容易推理。 此外，正如我将简要介绍的那样，以这种方式拆分可以让您重新组合不同的部分，以自定义过滤记录的方式等。

如果它分裂了一点：

def _get_single_record(id):
    """ Request an individual financial position.
        This does not filter """
    ... read and return the json decoded data ...

def _record_matches_sector(record, sector):
    """ Determine if the record provided matches the sector """
    return record['sector'] == sector

def _record_meets_closing_stock_limit(record, limit):
    """ Determine if the record provided has a
        closing stock of at least limit """
    return record['closing stock'] >= limit

def _get_all_filtered_records(ids, sector, limit):
    """ Return all financial position records that
        match the sector and closing stock limit """
    record_generator = (_get_single_record(id) for id in ids)
    return (
        record for record in record_generator
        if _record_matches_sector(record, sector)
        and _record_meets_closing_stock_limit(record, limit)
    )

这显然只返回一个生成器，它返回与您的扇区和限制匹配的记录。 您可以添加更多测试等，但更新代码以测试每个测试仍然非常手动。 您需要的是一种将一些可选测试应用于record_generator并返回匹配结果的方法。

这在python中非常简单，因为python将函数视为第一类对象（意味着您可以将它们分配给变量），并且您可以使用lambdas快速创建自定义函数。 这意味着您可以将_get_all_filtered_records为：

def _make_limit_test(limit):
    """ This returns a function which accepts records that meet the limit """
    return lambda record: record['closing stock'] >= limit

def _make_sector_test(sector):
    """ This returns a function which accepts records that match the sector """
    return lambda record: record['sector'] == sector

def _filter_records_by_tests(ids, tests):
     """ Returns all the records that pass all the tests """
     record_generator = (_get_single_financial_position_record(id) for id in ids)
     for record in record_generator:
         if all(test(record) for test in tests):
             yield record

然后，您可以通过询问用户来构建要传递的测试列表。 这将是一个足够的演示，只是为了验证这种方法是否有效：

def demo_filtering_by_healthcare_and_40k(ids):
    tests = [_make_sector_test("healthcare"), _make_limit_test(40000)]
    return _filter_records_by_tests(ids, tests)

正如您所看到的，我的方法名称很长，而且方法很短。 这实际上是个人风格的问题，但我发现以这种方式执行它会使方法显而易见，并允许您快速理解代码以验证它是否与名称匹配。

所以要包装它，你要从远程api请求记录。 您可以使用列表推导来过滤这些。 列表推导非常强大，允许您获取源数据并对其进行转换并对其进行过滤。 阅读它们会对你有很大帮助。