Python从0开始写爬虫——开发环境

Posted 2020-12-26 莫问今朝

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　　python小白，稍微看了点语法而已，连字典的切片都永不顺的那种。本身是写java的，其实java也写得菜，每天下了班不是太想写java。所以下班总是乱搞，什么都涉猎一点，也没什么太实际的收获。现在打算慢慢写个python爬虫玩

　　1. python环境搭建。我在windows上也是搭了python环境的，很久了。但是这个我在windows用pip安装的第三方库用起来总是报错。所以我一般都不用。我时用pycharm的python环境的。

　　　在pycharm上安装需要的包，新建项目后，在左上角 File ->> Settings,然后弹出如下界面。点击红色箭头处添加，然后搜索就行了。不推荐自己在windows装，没必要浪费时间搞windows的环境

　　2. linux上，我租的阿里服务器，装的是CentOS7, linux上安装python3我就不介绍了。主要提醒一下CentOS是自带python2.7的，而且有一些功能是要用的这个版本的python，比如yum，所以不要轻易卸载。

　　　我安装的python3。在控制台输入 python2 就进入python2.7的shell，输入python3就进入python3的shell。如下

[root@izwz94jyld0skyrwc1772ez ~]# python2
Python 2.7.5 (default, Jul 13 2018, 13:06:57) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 
>>> print \'hello, world\'
hello, world
>>> 
[1]+  Stopped                 python2


[root@izwz94jyld0skyrwc1772ez ~]# python3
Python 3.6.2 (default, Jul  8 2018, 11:17:50) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 
>>> print(\'Hello, World\')
Hello, World
>>>

但是在用 pip 安装第三方库的时候，只有python2能用。比如我安装个pandas。

[root@izwz94jyld0skyrwc1772ez ~]# pip install pandas
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Collecting pandas
  Downloading http://mirrors.aliyun.com/pypi/packages/65/b2/8c3a7fc10f581d0ef196e54ba13248e09b25012ab3b213cda83f8f5e7678/pandas-0.23.3-cp27-cp27mu-manylinux1_x86_64.whl (8.9MB)
    100% |████████████████████████████████| 8.9MB 75.9MB/s 
Collecting pytz>=2011k (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/30/4e/27c34b62430286c6d59177a0842ed90dc789ce5d1ed740887653b898779a/pytz-2018.5-py2.py3-none-any.whl (510kB)
    100% |████████████████████████████████| 512kB 81.3MB/s 
Collecting numpy>=1.9.0 (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/85/51/ba4564ded90e093dbb6adfc3e21f99ae953d9ad56477e1b0d4a93bacf7d3/numpy-1.15.0-cp27-cp27mu-manylinux1_x86_64.whl (13.8MB)
    100% |████████████████████████████████| 13.8MB 75.1MB/s 
Collecting python-dateutil>=2.5.0 (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/cf/f5/af2b09c957ace60dcfac112b669c45c8c97e32f94aa8b56da4c6d1682825/python_dateutil-2.7.3-py2.py3-none-any.whl (211kB)
    100% |████████████████████████████████| 215kB 85.7MB/s 
Requirement already satisfied: six>=1.5 in /usr/lib/python2.7/site-packages (from python-dateutil>=2.5.0->pandas) (1.11.0)
Installing collected packages: pytz, numpy, python-dateutil, pandas
Successfully installed numpy-1.15.0 pandas-0.23.3 python-dateutil-2.7.3 pytz-2018.5

然后我分别在python2和python3去使用它，会发现python2可以用而python3不能用

[root@izwz94jyld0skyrwc1772ez ~]# python2
Python 2.7.5 (default, Jul 13 2018, 13:06:57) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from pandas import DataFrame
/usr/lib64/python2.7/site-packages/pandas/_libs/__init__.py:4: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from .tslib import iNaT, NaT, Timestamp, Timedelta, OutOfBoundsDatetime
/usr/lib64/python2.7/site-packages/pandas/__init__.py:26: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import (hashtable as _hashtable,
/usr/lib64/python2.7/site-packages/pandas/core/dtypes/common.py:6: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import algos, lib
/usr/lib64/python2.7/site-packages/pandas/core/util/hashing.py:7: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import hashing, tslib
/usr/lib64/python2.7/site-packages/pandas/core/indexes/base.py:7: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import (lib, index as libindex, tslib as libts,
/usr/lib64/python2.7/site-packages/pandas/tseries/offsets.py:21: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  import pandas._libs.tslibs.offsets as liboffsets
/usr/lib64/python2.7/site-packages/pandas/core/ops.py:16: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import algos as libalgos, ops as libops
/usr/lib64/python2.7/site-packages/pandas/core/indexes/interval.py:32: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs.interval import (
/usr/lib64/python2.7/site-packages/pandas/core/internals.py:14: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import internals as libinternals
/usr/lib64/python2.7/site-packages/pandas/core/sparse/array.py:33: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  import pandas._libs.sparse as splib
/usr/lib64/python2.7/site-packages/pandas/core/window.py:36: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  import pandas._libs.window as _window
/usr/lib64/python2.7/site-packages/pandas/core/groupby/groupby.py:68: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import (lib, reduction,
/usr/lib64/python2.7/site-packages/pandas/core/reshape/reshape.py:30: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import algos as _algos, reshape as _reshape
/usr/lib64/python2.7/site-packages/pandas/io/parsers.py:45: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  import pandas._libs.parsers as parsers
/usr/lib64/python2.7/site-packages/pandas/io/pytables.py:50: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  from pandas._libs import algos, lib, writers as libwriters
>>> data={}
>>> data[\'a\'] = [1,2,3,4,5]
>>> data[\'b\'] = [6,7,8,9,0]
>>> data[\'c\'] = [11,12,13,14,15]
>>> df = DataFrame(data)
>>> print df
   a  b   c
0  1  6  11
1  2  7  12
2  3  8  13
3  4  9  14
4  5  0  15
>>> 

[8]+  Stopped                 python2
[root@izwz94jyld0skyrwc1772ez ~]# 
[root@izwz94jyld0skyrwc1772ez ~]# 
[root@izwz94jyld0skyrwc1772ez ~]# 
[root@izwz94jyld0skyrwc1772ez ~]# 
[root@izwz94jyld0skyrwc1772ez ~]# python3
Python 3.6.2 (default, Jul  8 2018, 11:17:50) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pandas import DataFrame
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named \'pandas\'
>>>

因为pip默认用的是python2的。所以如果我们要给python3 安装第三方库。不能直接用pip。应该用pip3.

[root@izwz94jyld0skyrwc1772ez ~]# 
[root@izwz94jyld0skyrwc1772ez ~]# pip3 install pandas
Looking in indexes: http://mirrors.aliyun.com/pypi/simple/
Collecting pandas
  Downloading http://mirrors.aliyun.com/pypi/packages/f4/cb/a801eaf624e36fffaa6cf1f4597a1e4b0742c200ed928e689c58fb3cb811/pandas-0.23.3-cp36-cp36m-manylinux1_x86_64.whl (8.9MB)
    100% |████████████████████████████████| 8.9MB 73.6MB/s 
Collecting pytz>=2011k (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/30/4e/27c34b62430286c6d59177a0842ed90dc789ce5d1ed740887653b898779a/pytz-2018.5-py2.py3-none-any.whl (510kB)
    100% |████████████████████████████████| 512kB 68.8MB/s 
Collecting numpy>=1.9.0 (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/88/29/f4c845648ed23264e986cdc5fbab5f8eace1be5e62144ef69ccc7189461d/numpy-1.15.0-cp36-cp36m-manylinux1_x86_64.whl (13.9MB)
    100% |████████████████████████████████| 13.9MB 75.1MB/s 
Collecting python-dateutil>=2.5.0 (from pandas)
  Downloading http://mirrors.aliyun.com/pypi/packages/cf/f5/af2b09c957ace60dcfac112b669c45c8c97e32f94aa8b56da4c6d1682825/python_dateutil-2.7.3-py2.py3-none-any.whl (211kB)
    100% |████████████████████████████████| 215kB 81.7MB/s 
Requirement already satisfied: six>=1.5 in /usr/local/python3/lib/python3.6/site-packages (from python-dateutil>=2.5.0->pandas) (1.11.0)
Installing collected packages: pytz, numpy, python-dateutil, pandas
Successfully installed numpy-1.15.0 pandas-0.23.3 python-dateutil-2.7.3 pytz-2018.5
You are using pip version 10.0.1, however version 18.0 is available.
You should consider upgrading via the \'pip install --upgrade pip\' command.
[root@izwz94jyld0skyrwc1772ez ~]# python3
Python 3.6.2 (default, Jul  8 2018, 11:17:50) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pandas import DataFrame
/usr/local/python3/lib/python3.6/importlib/_bootstrap.py:205: RuntimeWarning: numpy.dtype size changed, may indicate binary incompatibility. Expected 96, got 88
  return f(*args, **kwds)
>>> data={}
>>> data[\'b\'] = [6,7,8,9,0]
>>> data[\'b\'] = [6,7,8,9,0]
>>> data[\'c\'] = [11,12,13,14,15]
>>> df = DataFrame(data)
>>> print(df)
   b   c
0  6  11
1  7  12
2  8  13
3  9  14
4  0  15
>>>