List of lists: indexing and assigning values (Python) -


I'm sure this stupid is simple, but in some way I can not understand it. 

  a = [[0] * 4] * 3 a [0] [0] = 1 a [[1, 0, 0, 0], [1, 0, 0, 0 ], [1, 0, 0, 0]]   
 I'm just trying to allocate 1 to the first element in the first row. Instead, the value of the first element 1 is assigned to the  every  line. How should I indexing so that value can be assigned to the right element?  
 Thank you!  
 
 
 First you should understand this fact.  
 If you do  
  A = [5] * 3   
 It is a surprise that  a [0] ,  a [1]  and  one [2]  are the same thing you can do to ensure this by doing so.  
  id (a [0]) == ID (a [1]) == ID (a [2]) #True   
 Sounds like the following.  
  a [0] - + a [1] - + - - 5a [2] - +   
 If you do  
  a [0] = 10   
 The following is the like.  
  a [0] ----- & gt; 10 A [1] - + - - 5a [2] - +   
 OK. Now back to the list of your list's list. To simplify your problem, define  a :  
  a = [[4, 5, 6]] * 3   
 Unknowingly these are similar objects.  
  id (a [0]) == ID (a [1]) == ID (a [2]) #true   
 Sounds like the following.  
  a [0] - + a [1] - + - - [4, 5, 6] A [2] - +   
 If you  
  a [0] = 10   
 So it is like the following.  
  a [0] ----- & gt; 10 A [1] - + - - [4, 5, 6] A [2] - +   
 OK This is not a problem. Then you do this  
  a [1] [0] = 8   
 So it is like the following.  
  a [0] ----- & gt; 10 A [1] - + - - [8, 5, 6] One [2] - +   
 Done !! It's easy to understand.  
 HIH. :)

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