Connor's Feedback&Question on Chapter 2 about python-for-data-and-media-communication-gitbook HOT 3 CLOSED

Thanks @ConnorLi96 ! Clear written feedback. @ChicoXYC can you try to address the comments first? For better explaining certian concept, feel free to ask me. It also helps to link to different reading materials on a certain topic.

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@ConnorLi96 @hupili
Thanks so much. Add explanation of array.shape and index, hope it may be helpful for you. If you have more questions, free to ask.

• Array.shape

>>> b = np.array([[1,2,3],[4,5,6]])    # Create a rank 2 array
>>> print(b.shape)
(2, 3) #the first number means how many elements in this array, in this case, this array has two elements - two lists. The second number means how many sub-elements in each element. In this case, there are 3 values in each list. So, it's like a layer nesting.
>>> print(b[0, 0], b[0, 1], b[1, 0])
1 2 4 #you can access values by their index. Similarly, the first number is to index elements in this array, the second number is to index the sub-elements in each elements.

• About index in data types

Simply, Index is like the position of one element in the whole list or object, which used to access this element. The index of first element is 0 and increases by integer. The following are examples may help you better understand this.

    String  ‘H     e     l      l      o'
    Index   [0]   [1]   [2]    [3]    [4]
    List    ['a', 'b',  'c',   'd',   'e']
    Index   [0]   [1]   [2]    [3]    [4]

In the list ['a', 'b', 'c', 'd', 'e'], list[0]='a', 0 is the index of 'a' in this list, similarly use in array. We will use more in chapter 3 so that you can get more familiar with this issue.

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Thanks a lot! This explanation is very useful and help me to understand it totally.

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