python map visualization

Map--MappingReduce--InductionThe process of standardizing big dataMap unpacking task, reduce merges the resultsIs it possible to make many computers a supercomputer?Some questions: If the task itself is very complex, then dismantling the task itself is a very difficult problem.Python added the map reduce function when it was 2.6For example, we can write thisImport urllib2urls = [ ' https://www.baidu.com

The first name begins with the lower case; Practice:1 def Normalize (name): 2 return name[0].upper () + name[1:].lower ()3 L1 = ['Adam' 'LISA'barT']4 L2 = List ( Map (normalize, L1))5print(L2)Reduce quadrature: 1 from functools import reduce 2 3 def prod (L): Span style= "COLOR: #008080" >4 def FN (x, y): 5 return x * y 6 return reduce (FN, L) 7 print ( Span style= "COLOR: #800000" > " 3 * 5 * 7 * 9 = " , prod ([3, 5,

)] * k))>>> list (group_adjacent (a, 3))[(1, 2, 3), (4, 5, 6)]>>> list (group_adjacent (a, 2))[(1, 2), (3, 4), (5, 6)]>>> list (group_adjacent (a, 1))[(1,), (2,), (3,), (4,), (5,), (6,)]>>> list (zip (a[::2], a[1::2]))[(1, 2), (3, 4), (5, 6)]>>> list (zip (a[::3], a[1::3], a[2::3]))[(1, 2, 3), (4, 5, 6)]>>> group_adjacent = lambda a, k:zip (* (a[i::k] for I in range (k)))>>> list (group_adjacent (a, 3))[(1, 2, 3), (4, 5, 6)]>>> list (group_adjacent (a, 2))[(1, 2), (3, 4), (5, 6)]>>> list (group_

>>>filter (f, D)4[1, 2, 3]5>>> Map (LambdaX:x>2, D)6 [False, False, True]7>>>defF1 (s):8... s=s*1209 ...Ten>>>Map (F1, D) One[None, none, none]4. zip ([iterable, ...])Zip () is an intrinsic function of Python that takes a series of iterated objects as parameters, packages the corresponding elements in the object into tuple (tuples), and then returns a list of the

the map function is in the form: Map(function, iterable, ...) Function: Functions, containing two parametersIterable: One or more sequencesfunction functions can be created by themselves, previously using the contents of the CSV file to replace, for example, ' is ' replaced by ' yes ', some Chinese replaced by a digital representation.Iterable: Generally a list, which can be mapped together by functio

意结构')Print(Sumtree (L))##间接函数调用defEcho (message):Print(message)defIndirect (Func,args): func (args) indirect (echo,'Shixingwen') Schedule1=[(Echo,'spam! '), (Echo,'ham!') ] for(Func,args)inchSchedule1:func (args)Print('# #间接调用函数')Print(Echo.__name__)## #python function AnnotationsdefFunc (A:'spam', B: (1,3), c:float):returnA + B +CPrint('# #函数注释')Print(Func-)) Zhushi= Func.__annotations__ Print(Zhushi,'\ n') forArgsinchZhushi:Print(Args,'=', Zhushi

item order in sequence, if there is starting_ Value, which can also be called as an initial value, for example, can be used to sum the list: >>> def add (x, y): return x + y >>> Reduce (add, range (1, ) 55 (note: 1+2+3+4+5+6+7+8+9+10) >>> Reduce (add, range (1, one),) 75 (Note: 1+2+3+4+5+6+7 +8+9+10+20) Lambda: This is a funny syntax for Python, which allows you to quickly define the smallest function of a single line, similar to a macro in C,

Using the map () function, the nonstandard English name entered by the user becomes the first letter capitalized, and the other lowercase canonical names. Input: [' Adam ', ' Lisa ', ' Bart '], output: [' Adam ', ' Lisa ', ' Bart '].The sum () function provided by Python can accept a list and sum, write a prod () function that accepts a list and uses the reduce () to calculate the product.list=[' Adam ', '

/tuple/string and an initial value, and the return value is numeric.#Coding=utf-8" "Created on 2016-12-14@author:jennifer Project: Usage of filter, map, reduce, lambda in Python" "#1.LAMBDA usage, before the colon is the argument, after the colon is the expression, the return value, the simplest functionPrint[(LambdaX:X*X) (x) forXinchRange (11)]#results: [0, 1, 4, 9, (+) , +/-, +, +, Bayi, +]Print(LambdaX:

Recently in the reptile section of learning Python. See a netizen in sharing the use of crawler crawling all kinds of Web site's code, also want to write a play. Today took the time to analyze the structure of the sister map and HTML code, using URLLIB2 and BeautifulSoup wrote a automatic download pictures of the sister image of the script.Sister Figure website: http://www.mzitu.comThe results are as follow

Python has built-in special functions that are Python-specific. You can make your code more concise.Examples can be seen:1 filter (function, sequence):str = [' A ', ' B ', ' C ', ' d ']def fun1 (s): return s if s! = ' a ' else NoneRET = filter (FUN1, str)Print ret# # [' B ', ' C ', ' d ']A function (item) is executed on item in sequence, and the item that executes the result of true consists of a list/strin

example, you can use to sum a list:defAdd (x, y):returnX +yPrintReduce (Add, range (1, 11)) Note:1+2+3+4+5+6+7+8+9+10reduce (Add, range (1, 11), 20) Note:1+2+3+4+5+6+7+8+9+10+20 iv.Lambda This is Python support an interesting syntax that allows you to quickly define a single line of the smallest function, similar to the C language of the macro, these functions, called Lambda, is borrowed from Lisp, can be used in any need function of the place: G=Lam

Map ():map()The function receives two parameters, one is a function and the other isIterable>>> L = [I for I in range] #[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>>> list (map (str, l)) [' 0 ', ' 1 ', ' 2 ', ' 3 ', ' 4 ', ' 5 ', ' 6 ', ' 7 ', ' 8 ', ' 9 ']Build the list with the list generation first,Str is a function converted to a string,The

Reference from: Https://github.com/qiwsir/StarterLearningPython/blob/master/204.md#mapHttps://github.com/qiwsir/StarterLearningPython/blob/master/204.md#reduceMap (function name/functional expression (lambda, etc.)/..., parameter 1, parameter 2)Reduce (function name/functional expression (lambda, etc.)/..., parameter 1)Difference:1. Parameters: Reduce only one parameter is allowed in addition to the function, and map allows two2. Mode:

Limited support for anonymous functions 3. Higher-order functions in Python1) Custom High-order functions (functions as Parameters)Import Math def add (x, y, f): return F (x) + f (y)print add (9, math.sqrt)2) Built-in High-order functions Map function format: map (f, lst)F is the function name, can be a built-in function, or it can be a custom functionThe LST is a sequence to be

Problem: You want to access the element by name to reduce the dependency on the location in the structureSolution: Use the named Tuple collections.namedtuple (). It is a factory method that returns a subclass of the standard tuple type in Python, gives it a type name and the corresponding field name , returns a class that can be instantiated, gives you a defined field name to pass in the value, and so on.The primary purpose of a named tuple is to deco