Python Learning Notes (16) Looping objects

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Original chain: http://www.cnblogs.com/vamei/archive/2012/07/09/2582499.html

Note: There is a more awkward noun; table derivation, Generator Gen (), iterator (the job is not covered in a large space)

#16th Cycle Object forLineinchOpen'D:/pythonfiles/test.txt'):    Print(line)#output: print by row#1234#ABCD#EFG#The author means, should be the manual cycle, and then loop to the back, appear Stopinteration,python think the loop is done#for loop is to automatically call the next () method until Stopinteratrion appears#GeneratordefGen (): a= 100yielda A= A*8yieldayield1000 forIinchGen ():Print(i)#Output:# -# +#Gen () is like a function definition, and return is changed to yield.#can have multiple yield#Gen () pauses to run the generator after yield, returns the yield value, and when called again, resumes from the time of the pause to the next yield#the generator itself forms a circulator, with each loop using a yield return valuedefGen (): forIinchRange (4):        yieldI#Builder ExpressionG = (x forXinchRange (4))#G.next ()#Print Elements#Python2 can be implemented with. Next ()#Python3 Error, the attribute is wrong, because there is no such methodNext (G)#can be typed in sequence until the Stopinteration,loop is over.#Output" ">>> Next (g) 0>>> next (g) 1>>> next (g) 2>>> next (g) 3>>> next (g) Traceback (most recent): File "<pyshell#830>", line 1, in <module> next (G) stopiteration" "#Table DerivationL = []#L an empty list forXinchRange (10):#Loop to 9,range no upper limitL.append (x**2)#L increase x square at tailL#output: [0, 1, 4, 9, +,----L= [X**3 forXinchRange (10)]#output: [0, 1, 8, 216, 343, 729]#Job:XL = [1,3,5]yl= [9,12,13]l= [x**2 for(x, Y)inchZip (xl,yl)ifY > 10]#First ConversionXL = [1,3,5]yl= [9,12,13]l= [] for(x, Y)inchZip (xl,yl):ifY >10:        Print(x**2) L#Output 9#but not inside the list .XL= [1,3,5]yl= [9,12,13]l= [] for(x, Y)inchZip (xl,yl):ifY >10: L.append (x**2) L#output changed [9]Zip (xl,yl)#the output is (1, 9) (3, a) (5 )#the IF condition statement y>10 the square of the X#y is greater than 10, the second two, 3 squared, and 5 squared .#so the output should be [9,25]

Python Learning Notes (16) Looping objects