islice

;>> from Itertools Import count>>> counter = count (start=13)>>> Next (counter)13>>> Next (counter)14 To generate an infinite sequence from a finite sequence: >>> from Itertools Import cycle>>> colors = cycle ([' Red ', ' white ', ' Blue '])>>> Next (colors)' Red '>>> Next (colors)' White '>>> Next (colors)' Blue '>>> Next (colors)' Red ' To generate a finite sequence from an infinite sequence: >>> from Itertools import islice>>> colors = cycle ([

for this category include: 　 　accumulate()　　chain()/chain.from_iterable()　　compress()　　dropwhile()/filterfalse()/takewhile()　　groupby()　　islice()　　starmap()　　tee()　　zip_longest() Here we will not illustrate all the methods one by one. If you want to know the usage of a method, print (method. _ doc _). After all, the itertools module provides a shortcut without any esoteric algorithms. Here we will illustrate the following methods that I find interest

Itertools import count >>>wmyl88.com counter = count (start=13) >>> Next (counter) 13 >>> Next (counter) 14To generate an infinite sequence from a finite sequence:>>> from itertools import cycle >>> colors = cycle ([' Red ', ' white ', ' Blue ') >>> Next (colors) ' Red ' >>> Next (colors) ' White ' >>> Next (colors) ' Blue ' >>> Next (colors) ' red 'To generate a finite sequence from an infinite sequence:>>> from itertools import islice >>> colors =

#利用生成器生成一个可迭代对象#需求: Generates an iterative object, outputs a prime number within a specified range, and uses the generator to produce an iterative object#生成器: It is iterative in itself, but yield is like return, yield returns, function freezes state when re-tuned, starting from frozen state1 classPrintnumbers (object):2 """docstring for Printnumbers"""3 def __init__(self, start,end):4Self.start =Start5Self.end =End6 defIsprimenum (self,num):7 ifnum==2:8 returnFals

operation. The most common zip function belongs to this category, only zip is a built-in function. Complete methods for this category include: 　 　accumulate()　　chain()/chain.from_iterable()　　compress()　　dropwhile()/filterfalse()/takewhile()　　groupby()　　islice()　　starmap()　　tee()　　zip_longest() Here we will not illustrate all the methods one by one. If you want to know the usage of a method, print (method. _ doc _). After all, the itertools module p

what the function returns are iterator objects.Generate an infinite sequence:>>> from itertools import count>>> counter = count (start=13) >>> Next (counter) 13>>> Next (counter) 14To generate an infinite sequence from a finite sequence:>>> from itertools import cycle>>> colors = cycle ([' Red ', ' white ', ' Blue ']) >>> next (colors) ' Red ' >>> Next (colors) ' White ' >>> Next (colors) ' Blue ' >>> Next (colors) ' red 'To generate a finite sequence from an infinite sequence:>>> from itertool

returned iterator is an entry that returns an input iterator based on the index selectedCreates an iterator that generates an item in a way similar to the slice return value: iterable[start:stop:step], skips the previous start item, iterates over the stop at the specified stop, and step specifies the stride used to skip the item. Unlike slices, negative values are not used for any start,stop and step, and if Start is omitted, the iteration will start at 0 and if step is omitted, the stride will

When programming python, it is often necessary to skip the first line to read the contents of the file. It is easier to think of setting a line_num for each row, and then determining whether Line_num is 1, and if not equal to 1, reads. The corresponding Python code is as follows:[Python]View PlainCopy Input_file = open ("c:\\python34\\test.csv") Line_num = 0 For line in Islice (Input_file, 1, None): Line_num + = 1 if (line_

function returns are iterator objects.Generate an infinite sequence: from Import count>>> counter = count (start=13)>>> Next (counter)13>>> Next (counter)14To generate an infinite sequence from a finite sequence:>>> fromItertoolsImportCycle>>> colors = Cycle (['Red',' White','Blue'])>>>Next (colors)'Red'>>>Next (colors)' White'>>>Next (colors)'Blue'>>>Next (colors)'Red'To generate a finite sequence from an infinite sequence:>>> fromItertoolsImportIslice>>> colors = Cycle (['Red',' White','Blue'

infinite sequence: from Import count>>> counter = count (start=13)>>> Next (counter)13>>> Next (counter)14To generate an infinite sequence from a finite sequence:>>> fromItertoolsImportCycle>>> colors = Cycle (['Red',' White','Blue'])>>>Next (colors)'Red'>>>Next (colors)' White'>>>Next (colors)'Blue'>>>Next (colors)'Red'To generate a finite sequence from an infinite sequence:>>> fromItertoolsImportIslice>>> colors = Cycle (['Red',' White','Blue'])#Infinite>>> Limited =

In Python programming, you often need to skip the first line to read the contents of a file. It is easy to think of setting a line_num for each line, and then determining if Line_num is 1, and if not equal to 1, read the operation. The corresponding Python code is as follows: Input_file = open ("Test.csv") line_num = 0 for line in Islice (Input_file, 1, None): line_num + = 1 if (line _num!= 1): do_readline () However, thi

;> Zip (*z) [(1, 2, 3), (' A ', ' B ', ' C ')]1.12 Merging adjacent list items with a zip>>> a = [1, 2, 3, 4, 5, 6]>>> Zip (* ([ITER (a)] * 2)) [(1, 2), (3, 4), (5, 6)]>>> group_adjacent = Lambda A, K:zip (* ([ITER (a)] * k)) >>> Group_adjacent (A, 3) [(1, 2, 3), (4, 5, 6)]>>> group_adjacent (A, 2 ) [(1, 2), (3, 4), (5, 6)]>>> group_adjacent (A, 1) [(1,), (2,), (3,), (4,), (5,), (6,)]>>> Zip (a[::2], a[1 :: 2]) [(1, 2), (3, 4), (5, 6)]>>> zip (A[::3], A[1::3], A[2::3]) [(1, 2, 3), (4, 5, 6)]>>>