<机器学习实战>出现的Python函数查询

自己重写了一遍<机器学习实战>里的代码。只想吐槽<机器学习实战>书里样例代码写的跟屎一样，虽然书是好书。。。

ch2

2-1

from import和import https://www.zhihu.com/question/38857862

tile https://docs.scipy.org/doc/numpy/reference/generated/numpy.tile.html 类似broadcast

.sum(axis=1) 对二维array的行求和，axis=0是对列

.get(key,default value) 从字典中取对应key的value，若key不存在则返回default value

sorted https://docs.python.org/3/howto/sorting.html 搞清楚如何对tuple，对象，字典排序

.items() https://docs.python.org/3/library/stdtypes.html#mapping-types-dict 默认情况下，dict迭代的是key。如果要迭代value，可以用for value in d.values()，如果要同时迭代key和value，可以用for k, v in d.items()

为防止两个模块互相导入的问题，Python默认所有的模块都只导入一次，如果需要重新导入模块，
Python2.7可以直接用reload()，Python3可以用下面几种方法：

方法一：基本方法
from imp import reload
reload(module)

2-2

open 返回一个file对象，默认文件只读，记得用完关闭 https://docs.python.org/3/tutorial/inputoutput.html

.readlines() 用于读取所有行(直到结束符 EOF)并返回列表，该列表可以由 Python 的 for... in ... 结构进行处理

zeros https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.zeros.html

.strip https://www.tutorialspoint.com/python/string_strip.htm

.split http://python-reference.readthedocs.io/en/latest/docs/str/split.html

map http://www.runoob.com/python/python-func-map.html

.add_subplot http://blog.csdn.net/You_are_my_dream/article/details/53439518 推荐使用面向对象方式

.scatter https://matplotlib.org/api/_as_gen/matplotlib.pyplot.scatter.html

2-3

.min()全局 .min(0)对列 .min(1)对行

2-4

\ 表示行不够，另起一行写

print('%d and %f' % (a, b)) 格式化打印

2-5

input https://www.ibm.com/developerworks/cn/linux/l-python3-1/index.html

.readline http://www.runoob.com/python/file-readline.html

2-6

listdir http://www.runoob.com/python/os-listdir.html

ch3

3-1

.keys http://www.runoob.com/python/att-dictionary-keys.html

if currentLabel not in labelCounts.keys():

log https://docs.python.org/3.6/library/math.html

3-2

.extend http://www.runoob.com/python/att-list-extend.html

.append http://www.runoob.com/python/att-list-append.html

3-4

.count http://www.runoob.com/python/att-list-count.html

del（注意和.remove区别） http://www.jb51.net/article/35012.htm

subLabels = labels[:] 拷贝复制

3-5

dict http://www.runoob.com/python/python-func-dict.html

.figure https://matplotlib.org/api/_as_gen/matplotlib.pyplot.figure.html

.clf https://matplotlib.org/api/_as_gen/matplotlib.figure.Figure.html#matplotlib.figure.Figure

.subplot https://matplotlib.org/api/_as_gen/matplotlib.pyplot.subplot.html 注意与.add_subplot的区别，推荐使用后者

.annotate https://matplotlib.org/users/annotations.html#using-connectorpatch

3-6

.keys() http://www.runoob.com/python/att-dictionary-keys.html python3.6后返回的是迭代器，不支持索引(需将迭代器转换为list后，方可索引)

.values() http://www.runoob.com/python/att-dictionary-values.html python3.6后返回的是迭代器，不支持索引(需将迭代器转换为list后，方可索引)

type http://www.runoob.com/python/python-func-type.html

._name_ 类的默认静态变量　　

Spyder快捷键

Ctrl + 1: 注释/反注释

Ctrl + 4/5: 块注释/块反注释

Ctrl + s: 保存

3-7

.text https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.text.html#matplotlib.axes.Axes.text

3-8

.index http://www.runoob.com/python/att-list-index.html

3-9

pickle.dump & pickle.load https://blog.oldj.net/2010/05/26/python-pickle/ （代码有些过时） https://docs.python.org/3/library/pickle.html（新版说明）

open http://www.runoob.com/python/python-func-open.html

ch4

4-1

set http://blog.csdn.net/business122/article/details/7541486

list*5 把list扩展5倍

4-2

list.append([1,2,3]) list.extend([1,2,3])

4-5

python中字符串前的r表示不转义，常用于正则表达式 s = r'test\tddd' print(s) 输出: test\tddd

python正则表达式(贪婪匹配) http://www.runoob.com/python/python-reg-expressions.html

.lower() 字符串转为小写 .upper() 大写

.read() 返回一个字符串，包含文件里的所有内容

range(1,26) 1-25

random.shuffle() http://www.runoob.com/python/func-number-shuffle.html

python字符串编解码 https://www.cnblogs.com/evening/archive/2012/04/19/2457440.html

# -*- coding: UTF-8 -*- http://www.runoob.com/python/python-chinese-encoding.html

windows下的ANSI编码 https://mozillazg.com/2013/09/python-windows-ansi.html

python调试(使用pdb包，很强大) https://www.ibm.com/developerworks/cn/linux/l-cn-pythondebugger/

python调试(使用spyderIDE工具) http://blog.csdn.net/qq_33039859/article/details/54645465

4-6

如何获取Craigslist的RSS feed http://brittanyherself.com/cgg/tutorial-how-to-subscribe-to-craigslists-rss-feeds/

feedparser(主要搞懂字段feed，entries) http://pythonhosted.org/feedparser/common-rss-elements.html http://blog.topspeedsnail.com/archives/8156

机器学习实战作者使用的是这个网址的RSS源： https://newyork.craigslist.org/search/stp https://sfbay.craigslist.org/search/stp（ny.feed.link可以找到）

ny.feed.title ny.feed.title_detail(RSS地址) ny.feed.link(源网站地址) ny.entries ny.entries.title ny.entries.summary ny.entries.link ny.entries.published

min http://www.runoob.com/python/func-number-min.html

.remove（注意和del区别） http://www.runoob.com/python/att-list-remove.html

python取整 https://www.cnblogs.com/lipijin/p/3714312.html 另外int()也可以取整

新的stopwords list https://www.ranks.nl/stopwords

ch5

指示函数 http://www.cnblogs.com/xiaoxuesheng993/p/7977629.html

5-1

int() float()可以直接转字符串为数字 http://www.runoob.com/python/python-func-int.html

math.exp() http://www.runoob.com/python/func-number-exp.html

5-2

ax.scatter https://matplotlib.org/api/_as_gen/matplotlib.pyplot.scatter.html

arange https://docs.scipy.org/doc/numpy/reference/generated/numpy.arange.html

Pyplot tutorial（Pyplot入门，前者调用函数方式要搞清楚current figure和current axes的概念，而后者使用Artist方式调用函数(推荐)要搞清楚figure container和axes container）

https://matplotlib.org/tutorials/introductory/pyplot.html#sphx-glr-tutorials-introductory-pyplot-py

https://matplotlib.org/tutorials/intermediate/artists.html#sphx-glr-tutorials-intermediate-artists-py

numpy提供了很多math函数的副本，可以接受数组或者矩阵作为输入，返回相同大小的数组或者矩阵 numpy.exp numpy.cos

ch6

6-1

random.randrange https://docs.python.org/3/library/random.html

6-2

multiply https://docs.scipy.org/doc/numpy/reference/generated/numpy.multiply.html

python逻辑运算符 not or and http://www.runoob.com/python/python-operators.html

python直接赋值，浅拷贝，深拷贝 http://www.runoob.com/w3cnote/python-understanding-dict-copy-shallow-or-deep.html

matrix和二维array对列切片时，matrix返回的是列向量，二维array返回的是一维array

python后导入的包会覆盖前面导入的重名包 例如from numpy import *；import random python自带的random包会覆盖numpy.random

indexing with Boolean Arrays(数组过滤) https://docs.scipy.org/doc/numpy-dev/user/quickstart.html#indexing-with-boolean-arrays

6-3

matrix.A https://docs.scipy.org/doc/numpy-dev/reference/generated/numpy.matrix.A.html

nonzero https://docs.scipy.org/doc/numpy/reference/generated/numpy.nonzero.html 与indexing with boolean arrays配合使用有奇效

shape适合用于matrix，len适合用于array

<机器学习实战>出现的Python函数查询

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