python——CrawlSpiders類（深入爬取）

爬蟲的自我修養_5

一、CrawlSpiders類簡介

通過下面的命令可以快速創建 CrawlSpider模板 的代碼：

scrapy genspider -t crawl tencent tencent.com

上一個案例中，我們通過正則表達式，制作了新的url作為Request請求參數，現在我們可以換個花樣...

class scrapy.spiders.CrawlSpider

它是Spider的派生類，Spider類的設計原則是只爬取start_url列表中的網頁，而CrawlSpider類定義了一些規則(rule)來提供跟進link的方便的機制，從爬取的網頁中獲取link並繼續爬取的工作更適合。

源碼參考

class CrawlSpider(Spider):
    rules = ()
    def __init__(self, *a, **kw):
        super(CrawlSpider, self).__init__(*a, **kw)
        self._compile_rules()

    #首先調用parse()來處理start_urls中返回的response對象
    #parse()則將這些response對象傳遞給了_parse_response()函數處理，並設置回調函數為parse_start_url()
    #設置了跟進標志位True
    #parse將返回item和跟進了的Request對象    
    def parse(self, response):
        return self._parse_response(response, self.parse_start_url, cb_kwargs={}, follow=True)

    #處理start_url中返回的response，需要重寫
    def parse_start_url(self, response):
        return []

    def process_results(self, response, results):
        return results

    #從response中抽取符合任一用戶定義'規則'的鏈接，並構造成Resquest對象返回
    def _requests_to_follow(self, response):
        if not isinstance(response, HtmlResponse):
            return
        seen = set()
        #抽取之內的所有鏈接，只要通過任意一個'規則'，即表示合法
        for n, rule in enumerate(self._rules):
            links = [l for l in rule.link_extractor.extract_links(response) if l not in seen]
            #使用用戶指定的process_links處理每個連接
            if links and rule.process_links:
                links = rule.process_links(links)
            #將鏈接加入seen集合，為每個鏈接生成Request對象，並設置回調函數為_repsonse_downloaded()
            for link in links:
                seen.add(link)
                #構造Request對象，並將Rule規則中定義的回調函數作為這個Request對象的回調函數
                r = Request(url=link.url, callback=self._response_downloaded)
                r.meta.update(rule=n, link_text=link.text)
                #對每個Request調用process_request()函數。該函數默認為indentify，即不做任何處理，直接返回該Request.
                yield rule.process_request(r)

    #處理通過rule提取出的連接，並返回item以及request
    def _response_downloaded(self, response):
        rule = self._rules[response.meta['rule']]
        return self._parse_response(response, rule.callback, rule.cb_kwargs, rule.follow)

    #解析response對象，會用callback解析處理他，並返回request或Item對象
    def _parse_response(self, response, callback, cb_kwargs, follow=True):
        #首先判斷是否設置了回調函數。（該回調函數可能是rule中的解析函數，也可能是 parse_start_url函數）
        #如果設置了回調函數（parse_start_url()），那么首先用parse_start_url()處理response對象，
        #然后再交給process_results處理。返回cb_res的一個列表
        if callback:
            #如果是parse調用的，則會解析成Request對象
            #如果是rule callback，則會解析成Item
            cb_res = callback(response, **cb_kwargs) or ()
            cb_res = self.process_results(response, cb_res)
            for requests_or_item in iterate_spider_output(cb_res):
                yield requests_or_item

        #如果需要跟進，那么使用定義的Rule規則提取並返回這些Request對象
        if follow and self._follow_links:
            #返回每個Request對象
            for request_or_item in self._requests_to_follow(response):
                yield request_or_item

    def _compile_rules(self):
        def get_method(method):
            if callable(method):
                return method
            elif isinstance(method, basestring):
                return getattr(self, method, None)

        self._rules = [copy.copy(r) for r in self.rules]
        for rule in self._rules:
            rule.callback = get_method(rule.callback)
            rule.process_links = get_method(rule.process_links)
            rule.process_request = get_method(rule.process_request)

    def set_crawler(self, crawler):
        super(CrawlSpider, self).set_crawler(crawler)
        self._follow_links = crawler.settings.getbool('CRAWLSPIDER_FOLLOW_LINKS', True)

二、LinkExtractors

Link Extractors 的目的很簡單: 提取鏈接｡

每個LinkExtractor有唯一的公共方法是 extract_links()，它接收一個 Response 對象，並返回一個 scrapy.link.Link 對象。

Link Extractors要實例化一次，並且 extract_links 方法會根據不同的 response 調用多次提取鏈接｡

主要參數

class scrapy.linkextractors.LinkExtractor(
    allow = (),		# 滿足括號中“正則表達式”的值會被提取，如果為空，則全部匹配
    deny = (),		# 與這個正則表達式(或正則表達式列表)不匹配的URL一定不提取
    allow_domains = (),		# 會被提取的鏈接的domains
    deny_domains = (),		# 一定不會被提取鏈接的domains
    deny_extensions = None,
    restrict_xpaths = (),	# 使用xpath表達式，和allow共同作用過濾鏈接（一般只用allow就行了）
    tags = ('a','area'),
    attrs = ('href'),
    canonicalize = True,
    unique = True,
    process_value = None
)

三、LinkExtractors

在rules中包含一個或多個Rule對象，每個Rule對爬取網站的動作定義了特定操作。如果多個rule匹配了相同的鏈接，則根據規則在本集合中被定義的順序，第一個會被使用。

主要參數

class scrapy.spiders.Rule(
        link_extractor, 
        callback = None, 
        cb_kwargs = None, 
        follow = None, 
        process_links = None, 
        process_request = None
)

• link_extractor：是一個Link Extractor對象，用於定義需要提取的鏈接。

• callback： 從link_extractor中每獲取到鏈接時，參數所指定的值作為回調函數，該回調函數接受一個response作為其第一個參數。

  注意：當編寫爬蟲規則時，避免使用parse作為回調函數。由於CrawlSpider使用parse方法來實現其邏輯，如果覆蓋了 parse方法，crawl spider將會運行失敗。

• follow：是一個布爾(boolean)值，指定了根據該規則從response提取的鏈接是否需要跟進。 如果callback為None，follow 默認設置為True ，否則默認為False。

• process_links：指定該spider中哪個的函數將會被調用，從link_extractor中獲取到鏈接列表時將會調用該函數。該方法主要用來過濾。

• process_request：指定該spider中哪個的函數將會被調用， 該規則提取到每個request時都會調用該函數。 (用來過濾request)

小Tips

由於CrawlSpider使用parse方法來實現其邏輯，如果覆蓋了 parse方法，crawl spider將會運行失敗。

四、Logging

Scrapy提供了log功能，可以通過 logging 模塊使用。

可以修改配置文件settings.py，任意位置添加下面兩行。

LOG_FILE = "TencentSpider.log"
LOG_LEVEL = "INFO"

Log levels

• Scrapy提供5層logging級別:

• CRITICAL - 嚴重錯誤(critical)

• ERROR - 一般錯誤(regular errors)
• WARNING - 警告信息(warning messages)
• INFO - 一般信息(informational messages)
• DEBUG - 調試信息(debugging messages)

logging設置

通過在setting.py中進行以下設置可以被用來配置logging:

1. LOG_ENABLED 默認: True，啟用logging
2. LOG_ENCODING 默認: 'utf-8'，logging使用的編碼
3. LOG_FILE 默認: None，在當前目錄里創建logging輸出文件的文件名
4. LOG_LEVEL 默認: 'DEBUG'，log的最低級別
5. LOG_STDOUT 默認: False 如果為 True，進程所有的標准輸出(及錯誤)將會被重定向到log中。例如，執行 print "hello" ，其將會在Scrapy log中顯示。

 示例1、使用CrawlSpider爬取騰訊招聘網站

爬蟲模塊

# -*- coding: utf-8 -*-
import scrapy
from scrapy.linkextractors import LinkExtractor # 導入鏈接規則匹配類，用來提取符合規則的連接
from scrapy.spiders import CrawlSpider, Rule    # 導入CrawlSpider類和Rule
from day_31.TencentCrawlSpider.TencentCrawlSpider.items import TencentcrawlspiderItem


class TencentSpider(CrawlSpider):
    name = 'tencent'
    allowed_domains = ['tencent.com']
    start_urls = ['http://hr.tencent.com/position.php?&start=0']

    rules = (
        Rule(LinkExtractor(allow=r'position\.php\?&start=\d+#a'), callback='parse_item', follow=True),
        # Response里鏈接的提取規則，返回的符合匹配規則的鏈接匹配對象的列表
        # 獲取這個列表里的鏈接，依次發送請求，並且繼續跟進，調用指定回調函數處理
        # 前面加r表示將正則表達式編譯成一個規則的對象
    )

    # 指定的回調函數
    def parse_item(self, response):
        for i in response.xpath('//tr[@class="even"] | //tr[@class="odd"]'):
            item = TencentcrawlspiderItem()
            item['name'] = i.xpath(".//a/text()").extract()[0]
            item['link'] = i.xpath(".//a/@href").extract()[0]
            item['type'] = i.xpath("./td[2]/text()").extract()[0]
            item['number'] = i.xpath(".//td[3]/text()").extract()[0]
            item['place'] = i.xpath(".//td[4]/text()").extract()[0]
            item['rtime'] = i.xpath(".//td[5]/text()").extract()[0]
            yield item

管道模塊

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html
import json

class TencentcrawlspiderPipeline(object):
    def __init__(self):
        self.file = open('tencent-job.json','wb')

    def process_item(self, item, spider):
        text = json.dumps(dict(item),ensure_ascii=False)+'\n'
        self.file.write(text.encode('utf-8'))
        return item

    def close_spider(self, spider):
        self.file.close()

import scrapy

class TencentcrawlspiderItem(scrapy.Item):
    # define the fields for your item here like:
    name = scrapy.Field()
    link = scrapy.Field()
    type = scrapy.Field()
    number = scrapy.Field()
    place = scrapy.Field()
    rtime = scrapy.Field()

# -*- coding: utf-8 -*-

# Scrapy settings for TencentCrawlSpider project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'TencentCrawlSpider'

SPIDER_MODULES = ['TencentCrawlSpider.spiders']
NEWSPIDER_MODULE = 'TencentCrawlSpider.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'TencentCrawlSpider (+http://www.yourdomain.com)'

# Obey robots.txt rules
# ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
    'User-Agent':'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
  # 'Accept-Language': 'en',
}

LOG_FILE = 'tencentlog.txt'
LOG_LEVEL = 'DEBUG'
# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'TencentCrawlSpider.middlewares.TencentcrawlspiderSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'TencentCrawlSpider.middlewares.MyCustomDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   'TencentCrawlSpider.pipelines.TencentcrawlspiderPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

小Tips

1、python 爬蟲爬取內容時， \xa0 、 \u3000 的含義

\xa0 是不間斷空白符  

我們通常所用的空格是 \x20 ，是在標准ASCII可見字符 0x20~0x7e 范圍內。
而 \xa0 屬於 latin1 （ISO/IEC_8859-1）中的擴展字符集字符，代表空白符nbsp(non-breaking space)。
latin1 字符集向下兼容 ASCII （ 0x20~0x7e ）。通常我們見到的字符多數是 latin1 的，比如在 MySQL 數據庫中。

\u3000 是全角的空白符

根據Unicode編碼標准及其基本多語言面的定義， \u3000 屬於CJK字符的CJK標點符號區塊內，是空白字符之一。它的名字是 Ideographic Space ，有人譯作表意字空格、象形字空格等。顧名思義，就是全角的 CJK 空格。它跟 nbsp 不一樣，是可以被換行間斷的。常用於制造縮進， wiki 還說用於抬頭，但沒見過。

2、response.url    # 獲取當前頁面url

3、在allow里面的正則匹配，有特殊字符('.','?')要加轉義字符'\'
page_lx = LinkExtractor(allow=('position\.php\?&start=\d+'))

4、字符串去空格 str.strip()

示例二：爬取網頁里面的信息（東莞）

爬蟲模塊

# -*- coding: utf-8 -*-
import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
from newdongguan.items import NewdongguanItem


class DongdongSpider(CrawlSpider):
    name = 'dongdong'
    allowed_domains = ['wz.sun0769.com']
    start_urls = ['http://wz.sun0769.com/index.php/question/questionType?type=4&page=']

    # 每一頁的匹配規則
    pagelink = LinkExtractor(allow=("type=4"))
    # 每一頁里的每個帖子的匹配規則
    contentlink = LinkExtractor(allow=(r"/html/question/\d+/\d+.shtml"))

    rules = (
        Rule(pagelink),
        Rule(contentlink, callback = "parse_item"，follow=False)
    )

    def parse_item(self, response):
        item = NewdongguanItem()
        # 標題
        item['title'] = response.xpath('//div[contains(@class, "pagecenter p3")]//strong/text()').extract()[0]
        # 編號
        item['number'] = item['title'].split(' ')[-1].split(":")[-1]
        # 內容，先使用有圖片情況下的匹配規則，如果有內容，返回所有內容的列表集合
        content = response.xpath('//div[@class="contentext"]/text()').extract()
        # 如果沒有內容，則返回空列表，則使用無圖片情況下的匹配規則
        if len(content) == 0:
            content = response.xpath('//div[@class="c1 text14_2"]/text()').extract()
            item['content'] = "".join(content).strip()
        else:
            item['content'] = "".join(content).strip()
        # 鏈接
        item['url'] = response.url

        yield item

管道模塊

# -*- coding: utf-8 -*-

# Define your item pipelines here
#
# Don't forget to add your pipeline to the ITEM_PIPELINES setting
# See: http://doc.scrapy.org/en/latest/topics/item-pipeline.html
import json

class DongguancrawlspiderPipeline(object):
    def __init__(self):
        self.file = open('dongguan.json','wb')

    def process_item(self, item, spider):
        text = json.dumps(dict(item),ensure_ascii=False)+'\n'
        self.file.write(text.encode('utf-8'))
        return item

    def close_spider(self,spider):
        self.file.close()

import scrapy

class DongguancrawlspiderItem(scrapy.Item):
    # define the fields for your item here like:
    title = scrapy.Field()
    content = scrapy.Field()
    url = scrapy.Field()
    number = scrapy.Field()

# -*- coding: utf-8 -*-

# Scrapy settings for DongguanCrawlSpider project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     http://doc.scrapy.org/en/latest/topics/settings.html
#     http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#     http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html

BOT_NAME = 'DongguanCrawlSpider'

SPIDER_MODULES = ['DongguanCrawlSpider.spiders']
NEWSPIDER_MODULE = 'DongguanCrawlSpider.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = 'DongguanCrawlSpider (+http://www.yourdomain.com)'

# Obey robots.txt rules
# ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See http://scrapy.readthedocs.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
DEFAULT_REQUEST_HEADERS = {
    'User-Agent':'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
  # 'Accept-Language': 'en',
}

LOG_FILE = 'dongguan.log'
LOG_LEVER = 'DEBUG'

# Enable or disable spider middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    'DongguanCrawlSpider.middlewares.DongguancrawlspiderSpiderMiddleware': 543,
#}

# Enable or disable downloader middlewares
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    'DongguanCrawlSpider.middlewares.MyCustomDownloaderMiddleware': 543,
#}

# Enable or disable extensions
# See http://scrapy.readthedocs.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    'scrapy.extensions.telnet.TelnetConsole': None,
#}

# Configure item pipelines
# See http://scrapy.readthedocs.org/en/latest/topics/item-pipeline.html
ITEM_PIPELINES = {
   'DongguanCrawlSpider.pipelines.DongguancrawlspiderPipeline': 300,
}

# Enable and configure the AutoThrottle extension (disabled by default)
# See http://doc.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See http://scrapy.readthedocs.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = 'httpcache'
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = 'scrapy.extensions.httpcache.FilesystemCacheStorage'

1、提取出來的鏈接可能被篡改，所以我們可以通過process_link來修改url（一般不會遇到）

import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
from newdongguan.items import NewdongguanItem


class DongdongSpider(CrawlSpider):
    name = 'dongdong'
    allowed_domains = ['wz.sun0769.com']
    start_urls = ['http://wz.sun0769.com/index.php/question/questionType?type=4&page=']

    # 每一頁的匹配規則
    pagelink = LinkExtractor(allow=("type=4"))
    # 每一頁里的每個帖子的匹配規則
    contentlink = LinkExtractor(allow=(r"/html/question/\d+/\d+.shtml"))

    rules = (
        # 本案例的url被web服務器篡改，需要調用process_links來處理提取出來的url
        Rule(pagelink, process_links = "deal_links"),
        Rule(contentlink, callback = "parse_item")
    )

    # links 是當前response里提取出來的鏈接列表
    def deal_links(self, links):
        for each in links:
            each.url = each.url.replace("?","&").replace("Type&","Type?")
        return links

    def parse_item(self, response):
        ...

2、修改成spider類

# -*- coding: utf-8 -*-
import scrapy
from newdongguan.items import NewdongguanItem


class DongdongSpider(scrapy.Spider):
    name = 'xixi'
    allowed_domains = ['wz.sun0769.com']
    url = 'http://wz.sun0769.com/index.php/question/questionType?type=4&page='
    offset = 0
    start_urls = [url + str(offset)]


    def parse(self, response):
        # 每一頁里的所有帖子的鏈接集合
        links = response.xpath('//div[@class="greyframe"]/table//td/a[@class="news14"]/@href').extract()
        # 迭代取出集合里的鏈接
        for link in links:
            # 提取列表里每個帖子的鏈接，發送請求放到請求隊列里,並調用self.parse_item來處理
            yield scrapy.Request(link, callback = self.parse_item)

        # 頁面終止條件成立前，會一直自增offset的值，並發送新的頁面請求，調用parse方法處理
        if self.offset <= 71160:
            self.offset += 30
            # 發送請求放到請求隊列里，調用self.parse處理response
            yield scrapy.Request(self.url + str(self.offset), callback = self.parse)

    # 處理每個帖子的response內容
    def parse_item(self, response):
        item = NewdongguanItem()
        # 標題
        item['title'] = response.xpath('//div[contains(@class, "pagecenter p3")]//strong/text()').extract()[0]
        # 編號
        item['number'] = item['title'].split(' ')[-1].split(":")[-1]
        # 內容，先使用有圖片情況下的匹配規則，如果有內容，返回所有內容的列表集合
        content = response.xpath('//div[@class="contentext"]/text()').extract()
        # 如果沒有內容，則返回空列表，則使用無圖片情況下的匹配規則
        if len(content) == 0:
            content = response.xpath('//div[@class="c1 text14_2"]/text()').extract()
            item['content'] = "".join(content).strip()
        else:
            item['content'] = "".join(content).strip()
        # 鏈接
        item['url'] = response.url

        # 交給管道
        yield item

小Tips：

list = [a,b,c]
string = "123".join(list)
print(string)
>> a 123b 123c

string.replace("\xa0","")	# 將空格換成空

string.strip()		# 去首尾的空格
string.lstrip()		# 去左邊（前面）的空格
string.rstrip()		# 去右邊（后面）的空格