Python Learning Note--coursera

Someting about Lists mutation

1 ###################################2 #Mutation vs. Assignment3 4 5 ################6 #Look alike, but different7 8A = [4, 5, 6]9b = [4, 5, 6]Ten Print "Original A and B:", A, b One Print "is they same thing?"+ F isb A  -A[1] = 20 - Print "New A and B:", A, b the Print -  - ################ - #aliased +  -c = [4, 5, 6] +D =C A Print "Original C and D:", C, D at Print "is they same thing?"+ D isD -  -C[1] = 20 - Print "New C and D:", C, D - Print -  in ################ - #Copied to  +e = [4, 5, 6] -f =list (e) the Print "Original E and F:", E, F * Print "is they same thing?"E isF $ Panax NotoginsengE[1] = 20 - Print "New E and F:", E, F the Print +  A  the ################################### + #Interaction with Globals -  $  $A = [4, 5, 6] -  - defMutate_part (x):#Note: The A defaults to global theA[1] =x - Wuyi defassign_whole (x): theA =x -  Wu defAssign_whole_global (x): -     Globala AboutA =x $  -Mutate_part (100) - Printa -  AAssign_whole (200) + Printa the  -Assign_whole_global (300) $ PrintA

Here the assignment needs to be noted:

b = A, then A, B points to the same piece of memory, to a[1] or b[1] assignment, can change the list;

b = List (a), then A, B points to different memory.

Global vs Local

Mutate_part (x) This function changes the a[1], where a is defaulted to global;

A in Assign_whole (x) is local.

Assign_whole_global (x) wants to make changes to global variables, so add the Global keyword

Lists & Tuples (multi-group)

difference: Lists is mutable; Tuples is immutable, strings is the same as tuples, immutable.

Python Learning Note--coursera