python cookbook third edition

: Network Disk DownloadContent Introduction······"Python Cookbook (3rd edition) Chinese version" describes the Python application in various areas of the use of techniques and methods, its topics cover the data structure and algorithms, strings and text, numbers, dates and times, iterators and generators, files and I/O

,elem.text Since Iterparse is able to scan the elements and get the corresponding text. Then we can convert this function to a builder. The code is modified as follows: defXml_try (Element):Tag_indicate=[]Doc2=iterparse (R ' D:\test_source\rss20.xml ',(' Start ',' End ')) forevent,elem in doc2: if event = = ' start ' : Tag_indicate.append ( Elem.tag) if event = = ' end ' : if tag_indicate.pop () = = element: yield Elem.text __name__==' __main__

to use the extension code to perform the correct conversion, as follows:Static Pyobject *py_print_chars (Pyobject *self, Pyobject *args) { char *s = 0; int Len; if (! Pyarg_parsetuple (args, "es#", "Encoding-name", s, len)) { return NULL; } Print_chars (S, Len); Pymem_free (s); Py_return_none;}Finally, if you want to work directly with Unicode strings, here is an example that shows the underlying operation access:Static Pyobject *py_print_wchars (Pyobject *self, Pyobject *args) { p

first list (such as L[B1] 's head), as H.2 if H does not appear at the end of the other list, output it and remove it from all lists, then go back to step 1; otherwise, take the head of the next list as H and proceed with the step.3 Repeat the above steps until the list is empty, or you can no longer find out which elements to output. If this is the case, then the algorithm ends; if it is the latter case, it means that the inheritance relationship cannot be built, and

causes reference count +1: Objects are created, such as N=1 object is referenced, such as N1=n The object is passed into a function as a parameter, for example, func (n) Object as an element, stored in a container, such as LIST1=[N,N1] Case that causes reference count-1 The alias of the object is explicitly destroyed, for example del a The alias of the object is assigned a new object, such as a=2 An object leaves its scope, such as the local variable i

a Python object to the corresponding C parameter.This section of code uses Python's caching protocol to match any input parameter that looks like a double-precision array(such as numpy arrays, arrays created by array modules, etc.), refer to section 15.3 for more information.Inside the TYPEMAP code, variable substitution such as $ and $ will get the C parameter value of Typemap mode(for example, map to double*a ). $input point to a parameter as input

;Fromllvm.eeImportExecutionengine>>>Engine=Executionengine.New(MoD)>>>Ptr=Engine.Get_pointer_to_function(F)>>>Ptr4325863440>>>Foo=cTYPES.Cfunctype(cTYPES.C_double,cTYPES.c_doublectypes. C_double) (ptr) >>> # Call the resulting Function>>> foo (23) 13.0>>> foo (4,5) Span class= "Go" >41.0>>> foo (1 ,2) 5.0>>> It's not that making any mistakes at this level will cause the Python interpreter to hang up.Remember that you are dealing directly with machi

;>Print_chars.Argtypes=(cTYPES.C_char_p,)>>> print_chars (b " Hello World ' ) 48 6c 6c 6f (6f) 6c 64>>> print_chars (b ' hello\x00 World ' 48 6c 6c 6f>>> print_chars ' Hello World ' ) traceback (most recent call last): File "1, argument 1: >>> If you want to pass a string instead of a byte, you need to perform a manual UTF-8 encoding first. For example:Print_chars(' Hello World '). Encode(' utf-8 '))6c 6c 6f, 6f 6c>>> For other extension tools (such as Swig, Cython),When you use them

: resourcewarning:unclosed file mode= ' R ' encoding= ' UTF-8 ' >>>> By default, not all warning messages will appear. -w option to control the output of the warning message. -wall All warning messages will be output, -wignore Ignore all warnings, -werror Convert warnings to exceptions. Another option, you can also use warnings.simplefilter () function control output. always parameters will cause all warning messages to appear " Ignore Ignore all warnings, error

DBecause if 2 different keys correspond to the same value, one of the 2 keys will definitely disappear for the 2 functions given by the solution.Thus the generated pseudo-inverse dictionary length will be shorter than the original dictionary length, in any case, only if the value in D is hashed, then the previous function will work properly, otherwise the function would give a TypeError exceptionThis function obtains the Iteritems method to generate a pair of keys and other corresponding values

',' Tuesday ',' Wednesday ', ' Thursday ' ,' Friday ',' Saturday ',' Sunday ']Start_date=datetime.today ()#weekday的作用是得出当日在这周中的索引. For example, the Monday to Sunday indexes wereDay_num=start_date.weekday ()#得到目标日期的索引Day_num_target=weekdays.index (Dayname)#求得日期的差距, if the gap is 0, then days_ago=7, that's exactly one weeks apart.days_ago= (7+day_num-day_num_target)%70:days_ago=7Target_date=start_date-timedelta (days=days_ago)Target_date__name__==' __main__ ':#找到上一个周一的时间Get_previous_day (' Monday

follows:E:\python2.7.11\python.exe e:/py_prj/python_cookbook/chapter5.pyCall Decorator_tryCall ExampleWrapperThe result of example.__name__ here is wrapper, not example. That is, the properties of the modified function have changed. Because the adorner can be equivalent to write Example=decorator_try (example). The return value of Decorator_try is wrapper. So the example attribute is then changed to wrapper. To eliminate this effect, we need to use wraps.After modifying the wrapper with wraps,

observe variable values or tap a command such as w to get tracking information.Discuss?Don't make debugging too complicated. Some simple bugs just need to see the program stack information,The actual error is generally the last line of the stack.When you are developing, you can also insert them where you need to debug.print()function to diagnose the information (just delete these print statements when the last release is needed).A common use of the debugger is to observe a variable in a functio

expression, such as the equals sign, plus sign, and valuetokens = [(' NAME ', ' foo '), (' EQ ', ' = '), (' NUM ', ' * '), (' PLUS ', ' + '),(' num ', ' a '), (' Times ', ' * '), (' Num ', 10 ')]The code we tried is as followsPattern_try ():/* First define each matching pattern */R ' (? pR ' (? pR ' (? pR ' (? pR ' (? pR ' (? p/* Then summarize all the regular expressions */Master_pat = Re.compile (' | '). Join ([NAME, NUM, PLUS, Times, EQ, WS]))/* string scanning using scanner */Scanner = Mast

a success to see when the value2 is assigned. In the same way, we can use __setattr__ to prevent subsequent assignments of properties that are already in the class: classGet_try ():def__init__(Self, value):Self. value=valuedef__getattr__(Self, item): Self. Value=itemdef__getattribute__(Self, item):PrintItemdef__setattr__(Self, key, value):offKeyinchSelf.__dict__: Print ' already exist 'else :self. __dict__[Key]=valueif __name__ = = "__main__":G=get_try (' value ')G.value=4g.value1=3Print

14.10 re-throw the caught exception?You caught an except exception in a block and now want to re-throw it.Solution?Simply use a single rasie statement, for example:>>>DefExample():...Try:...int ( ' n/a ' ) ... except valueerror: ... print ( "didn ' t work" ) ... raise ... >>> example () didn ' t work traceback (most recent call last): File "1, in span class= "n" > "3, in Examplevalueerror: invalid literal for int. () with base: ' N/a ' > >> Discuss?The problem is usually when y

strings:S[::-1]Reverse the word only:Import reRev = Re.split (R ' (\s+) ', ' Hello World hahaha! ‘)Rev.reverse ()Rev = '. Join (REV) #要用空字符来join because the space is already in the cut listReturns all elements in a that are not part of B:Set (a). Difference (set (b))Translate method:Import strings = ' Hello world! 'Table = String.maketrans (' abcde ', ' 12345 ') #先生成对照表S.translate (table) #依照对照表进行替换操作S.translate (table, ' wor ') #替换后, delete characters containing worIf you want to delete only,

;>>should be Bar:item ('Bar') should be Spam:item ('spam') should be Foo:item ('Foo') should be Grok:item ('Grok')>>>You can see that the element returned at the first execution of the pop () operation has the highest priority, and the order of two elements (Foo and gork) of the same priority is returned in the same order as they were inserted into the queue.In this code, the queue is in the form of tuples (-priority, Self._index, item) , and The priority value is for the queue to be ranked in

Python cookbook (data structure and algorithm) is a method for decomposing sequences into individual variables. This example describes how to use a Python cookbook (data structure and algorithm) to separate sequences into individual variables. We will share this with you for your reference. The details are as follows:

Python Cookbook (2nd) Chinese Version Basic Information Author: Alex Martelli Anna Ravenscroft David AscherTranslator: Gao tiejun [same translator's work]Press: People's post and telecommunications PressISBN: 9787115222664Mounting time:Published on: February 1, May 2010Start: 16For more details, see: http://www.china-pub.com/196697The first five chapter sample read address: http://www.china-pub.com/computer