Python QuickStart
(→Quick Start) |
(→Format) |
||
(未显示1个用户的12个中间版本) | |||
第31行: | 第31行: | ||
<br><br> | <br><br> | ||
+ | |||
+ | == Bytes to string == | ||
+ | |||
+ | * https://blog.csdn.net/sinat_41104353/article/details/79283619 | ||
+ | |||
+ | <br> | ||
== Basics == | == Basics == | ||
第210行: | 第216行: | ||
Jack wrote Hello world | Jack wrote Hello world | ||
</source> | </source> | ||
+ | |||
+ | <br><br> | ||
+ | |||
+ | === yield === | ||
+ | |||
+ | 类 return 作用,不过返回的是生成器,可以用 for ... in generator 或 next 遍历该生成器 | ||
+ | |||
+ | * https://zhuanlan.zhihu.com/p/268605982 | ||
<br><br> | <br><br> | ||
第265行: | 第279行: | ||
== Data Structures == | == Data Structures == | ||
− | <br><br> | + | === Dict === |
+ | |||
+ | * https://www.runoob.com/python3/python3-dictionary.html | ||
+ | * https://www.jianshu.com/p/e6627929d379 | ||
+ | |||
+ | <br> | ||
+ | |||
+ | === List === | ||
+ | |||
+ | 中括号 [] 声明 | ||
+ | |||
+ | * https://www.runoob.com/python3/python3-list.html | ||
+ | |||
+ | <br> | ||
+ | |||
+ | === 元组 === | ||
+ | |||
+ | 括号声明,一旦定义 元素不可更改 | ||
+ | |||
+ | * https://www.runoob.com/python3/python3-tuple.html | ||
+ | |||
+ | <br> | ||
== Exceptions == | == Exceptions == | ||
第339行: | 第374行: | ||
* [https://matplotlib.org/gallery/statistics/histogram_cumulative.html?highlight=cdf hist.cdf] | * [https://matplotlib.org/gallery/statistics/histogram_cumulative.html?highlight=cdf hist.cdf] | ||
+ | |||
+ | <br> | ||
+ | |||
+ | == Numpy == | ||
+ | |||
+ | [https://www.delftstack.com/zh/howto/numpy/save-numpy-array-as-image/ 在 Python 中将 NumPy 数组保存为图像] | ||
+ | |||
+ | <source lang=python> | ||
+ | import numpy as np | ||
+ | import matplotlib.pyplot as plt | ||
+ | |||
+ | ds = np.arange(0,737280, 1, np.uint8) | ||
+ | ds = np.reshape(ds, (1024, 720)) | ||
+ | |||
+ | plt.imsave('test.jpg', ds) | ||
+ | </source> | ||
<br> | <br> | ||
第347行: | 第398行: | ||
* [https://www.jianshu.com/p/5ff47c7d0cc9 Seaborn Intro] | * [https://www.jianshu.com/p/5ff47c7d0cc9 Seaborn Intro] | ||
* https://zhuanlan.zhihu.com/p/24464836 | * https://zhuanlan.zhihu.com/p/24464836 | ||
+ | |||
+ | <br> | ||
+ | |||
+ | === Panel === | ||
+ | |||
+ | * https://panel.holoviz.org/gallery/index.html | ||
<br> | <br> | ||
第455行: | 第512行: | ||
* https://www.jianshu.com/p/491d6590b2a0 | * https://www.jianshu.com/p/491d6590b2a0 | ||
+ | |||
+ | <br> | ||
+ | |||
+ | == CSV == | ||
+ | |||
+ | <source lang=python> | ||
+ | import csv | ||
+ | csvfile = open('data-text.csv', 'rb') | ||
+ | reader = csv.reader(csvfile) | ||
+ | for row in reader: | ||
+ | print row | ||
+ | </source> | ||
<br> | <br> | ||
第526行: | 第595行: | ||
usage() | usage() | ||
sys.exit() | sys.exit() | ||
+ | |||
+ | def main(argv): | ||
+ | inputfile = '' | ||
+ | outputfile = '' | ||
+ | try: | ||
+ | opts, args = getopt.getopt(argv,"hi:o:",["ifile=","ofile="]) | ||
+ | except getopt.GetoptError: | ||
+ | print ('test.py -i <inputfile> -o <outputfile>') | ||
+ | sys.exit(2) | ||
+ | for opt, arg in opts: | ||
+ | if opt == '-h': | ||
+ | print ('test.py -i <inputfile> -o <outputfile>') | ||
+ | sys.exit() | ||
+ | elif opt in ("-i", "--ifile"): | ||
+ | inputfile = arg | ||
+ | elif opt in ("-o", "--ofile"): | ||
+ | outputfile = arg | ||
+ | print ('Input file is "', inputfile) | ||
+ | print ('Output file is "', outputfile) | ||
+ | |||
+ | if __name__ == "__main__": | ||
+ | main(sys.argv[1:]) | ||
</source> | </source> | ||
2022年4月8日 (五) 17:39的最后版本
目录 |
[编辑] 1 Quick Start
- Install python3.8 from https://www.python.org/downloads/
Install pip:
$ curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py $ sudo python get-pip.py
Using the pip to install the numpy and tensorflow package:
$ sudo pip3 install numpy pandas matplotlib $ sudo pip3 install scipy $ sudo pip3 install tensorflow
$ pip3 install --upgrade pip $ pip3 install jupyter
[编辑] 2 Bytes to string
[编辑] 3 Basics
[编辑] 3.1 Numbers
Python 2.7.9 (default, Mar 1 2015, 12:57:24) >>> a = 3.23 >>> b = 4 >>> c = 52.3E-4 >>> print a, b, c 3.23 4 0.00523
[编辑] 3.2 HEX
>>> print str(254) 254 >>> print hex(254) 0xfe >>> print hex(254).upper() 0XFE >>> str = "%02X" %(254); print str FE >>> print hex(1023) 0x3ff >>> print hex(1023)[0:-2] 0x3
[编辑] 3.3 Strings
#!/usr/bin/python str_1 = 'Jack Tan' str_2 = "Ga Xiao Duo" str_3 = '''This is a multi-line string. first line. second line''' # using the startswith method of the string object if str_1.startswith('Ja'): print("Yes, str_1 start with 'Ja'") if 'a' in str_1: print('Yes, str_1 contains the string "a"') substr = 'ac' if str_1.find(substr) != -1: print('Yes, str_1 contains the string "{0}"'.format(substr)) print('Yes, {0} contains the string "{1}"'.format('str_1', substr)) print('Yes, {} contains the string "{}"'.format('str_1', substr)) # using the format method of the string object deli = '_*_' mylist = ['Brazil', 'Russia', 'India', 'China'] # using the join method of the string object print(deli.join(mylist))
Output:
Yes, name start with 'Ja' Yes, name contains the string "a" Yes, name contains the string "ac" Brazil_*_Russia_*_India_*_China
Once your have created a string, you cannot change it
[编辑] 3.4 Variable
Python refers to anything used in a program as an object.
Do not need type declaration of variable in python
Python 2.7.9 (default, Mar 1 2015, 12:57:24) >>> a = 3.1415 >>> b = 100000 >>> c = 'Jack Tan' >>> d = ['x1', 'x2'] >>> print a, b, c, d 3.1415 100000 Jack Tan ['x1', 'x2'].
Variables can hold values of different types called data types. The basic types are numbers and strings. We can create our own types using classes.
[编辑] 3.5 Indentation
Whitespace at the beginning of the line is important!
Spaces and tabs at the beginning of the logical line are used to determine the indentation level of the logical line, which in turn is used to determine the grouping of statements.
Statements which go together must have the same indentation. Each usch set of statements is called a block
[编辑] 3.6 Format
#!/usr/bin/python #width = 10,precise = 3,align = left print "PI = %10.3f" %(math.pi) # don't add the '\n' at the end of line print "PI = %10.3f" %(math.pi), #width = 10,precise = 3,align = rigth print "PI = %-10.3f" % math.pi
Output:
PI = 3.141593 PI = 3.142
Python 2.7.9 (default, Mar 1 2015, 12:57:24) >>> print "%.3s " % ("jcodeer") #precise = 3 jco >>> print "%.*s" % (4,"jcodeer") #precise = 4 jcod >>> print "%10.3s" % ("jcodeer") #width = 10,precise = 3 jco >>>
fmat = "%r %r %r %r" print fmat % (1, 2, 3, 4) print fmat % ("one", "two", "three", "four") print fmat % (True, False, False, True)
1 2 3 4 'one' 'two' 'three' 'four' True False False True
print('{0:.3}'.format(0.3333333)) #print('{0:.3}'.format(1/3)) print('{0:_^11}'.format('Hello')) print('{0:+^11}'.format('Hello')) print('{name} wrote {book}'.format(name='Jack', book='Hello world'))
PI = 3.141593 PI = 3.142 0.333 ___Hello___ +++Hello+++ Jack wrote Hello world
[编辑] 3.7 yield
类 return 作用,不过返回的是生成器,可以用 for ... in generator 或 next 遍历该生成器
[编辑] 4 Operators
[编辑] 5 Control Flow
[编辑] 5.1 if
i = 5 if i == 0: print 'Zero' elif i > 0: print 'Positive' else: print 'Negative'
[编辑] 5.2 While
n = 4 while n: print 'Loop is OK' n -= 1 else: print 'Loop is over'
[编辑] 5.3 For
for ... in
for i in range(1,5): print i else: print 'The loop is over'
[编辑] 6 Functions
[编辑] 7 Data Structures
[编辑] 7.1 Dict
[编辑] 7.2 List
中括号 [] 声明
[编辑] 7.3 元组
括号声明,一旦定义 元素不可更改
[编辑] 8 Exceptions
[编辑] 8.1 with...as
#!/usr/bin/python import sys class test: def __enter__(self): print("enter") return 1 def __exit__(self, *args): print("clean up") return False #return True with test() as t: print("t is not the result of test(), it's __enter__ returned") print("t is 1, yes, it's {0}".format(t)) print "t is 1, yes, it's", t raise NameError("Error") sys.exit() print("Never here")
[编辑] 9 Matplotlib
- Gallery
- Change the Colors Changes to the default style
- Demo Fixed Size Axes
- Multiple Figs Demo
- Usetex Demo
- Controlling style of text and labels using a dictionary
- matplotlib.pyplot.plot()
- matplotlib.pyplot.figure()
[编辑] 9.1 bar
def currency(x, pos): """The two args are the value and tick position""" if x >= 1e6: s = '${:1.1f}M'.format(x*1e-6) else: s = '${:1.0f}K'.format(x*1e-3) return s formatter = FuncFormatter(currency) fig, ax = plt.subplots(figsize=(6, 8)) ax.xaxis.set_major_formatter(formatter)
[编辑] 9.2 hist
[编辑] 10 Numpy
import numpy as np import matplotlib.pyplot as plt ds = np.arange(0,737280, 1, np.uint8) ds = np.reshape(ds, (1024, 720)) plt.imsave('test.jpg', ds)
[编辑] 11 Seaborn
[编辑] 11.1 Panel
[编辑] 12 Modules
[编辑] 12.1 Serial
import serial import string import binascii s = serial.Serial('com4',9600) s.open() # rx data n = s.inwaiting() if n: data = str(binascii.b2a_hex(s.read(n)))[2:-1] print(data) # tx data d = bytes.fromhex('10 11 12 34 3f') s.write(d) s.close()
[编辑] 12.2 Struct (TX binary data)
import struct a = [0x00, 0x00, 0x00, 0x2c, 0x63, 0x00, 0x00, 0x00, 0x75, 0x4b, 0xef, 0x0f] s = socket.socket(socket.AF_INET,socket.SOCK_STREAM) s.connect(('127.0.0.1',8000)) date = struct.pack("%dB"%(len(a)),*a) s.send(date)
[编辑] 12.3 MQTT
Please refer to: http://wiki.jackslab.org/Noduino_OpenPlug#Turn_off_2
[编辑] 12.4 HTTP
httplib 实现了 http & https 的客户端协议,模块 urllib 和 urllib2 对 httplib 进行了更上层的封装
#!/usr/bin/env python # -*- coding:utf-8 -*- import urllib2 import json def http_post(url,data_json): jdata = json.dumps(data_json) req = urllib2.Request(url, jdata) response = urllib2.urlopen(req) return response.read() url = 'http://192.168.0.100:8080/dev/test' data_json = {'data' : '112233'} resp = http_post(url, data_json) print(resp)
使用post方式时,数据放在 data 或者 body 中:
import urllib import urllib2 test_data = {'ServiceCode':'aaaa','b':'bbbbb'} test_data_urlencode = urllib.urlencode(test_data) requrl = "http://192.168.1.16/dev/test" req = urllib2.Request(url = requrl, data =test_data_urlencode) print req res_data = urllib2.urlopen(req) res = res_data.read() print res
Python3:
import urllib.request as http resp = http.urlopen('http://iot.xxx.net') # print(resp.info()) resp.read() resp.close()
Reference: https://docs.python.org/3.8/library/urllib.request.html#module-urllib.request
[编辑] 13 CSV
import csv csvfile = open('data-text.csv', 'rb') reader = csv.reader(csvfile) for row in reader: print row
[编辑] 13.1 Time
[编辑] 13.2 PDF
$ pip3 install pdfplumber
Refer to: https://zhuanlan.zhihu.com/p/40221732
import pdfplumber import pandas as pd pdf = pdfplumber.open('ncp-who.pdf') page0 = pdf.pages[0] #PDF 文件的第一页 table = page0.extract_table() d = pd.DataFrame(table) print(d.loc[0]) d.to_csv('ncp-who.csv', index = False, header = True, date_format='%Y%m%d')
复杂的,参考:https://github.com/jsvine/pdfplumber/blob/master/examples/notebooks/extract-table-nics.ipynb
[编辑] 14 getopt
[编辑] 14.1 sys
import sys print(sys.argv[0]) for i in range(1, len(sys.argv)): print (i, sys.argv[i])
$ python test.py hello world test.py 1 hello 2 world
[编辑] 14.2 getopt
import sys, getopt opts, args = getopt.getopt(sys.argv[1:], "hi:o:") input_file="" output_file="" for op, value in opts: if op == "-i": input_file = value elif op == "-o": output_file = value elif op == "-h": usage() sys.exit() def main(argv): inputfile = '' outputfile = '' try: opts, args = getopt.getopt(argv,"hi:o:",["ifile=","ofile="]) except getopt.GetoptError: print ('test.py -i <inputfile> -o <outputfile>') sys.exit(2) for opt, arg in opts: if opt == '-h': print ('test.py -i <inputfile> -o <outputfile>') sys.exit() elif opt in ("-i", "--ifile"): inputfile = arg elif opt in ("-o", "--ofile"): outputfile = arg print ('Input file is "', inputfile) print ('Output file is "', outputfile) if __name__ == "__main__": main(sys.argv[1:])
[编辑] 15 Resource
- Online Python: http://www.compileonline.com/execute_python_online.php
- Python Quick Start: http://www.tutorialspoint.com/python/python_lists.htm