Return the number of rows of an array

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Riley 2021-5-25

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https://ww2.mathworks.cn/matlabcentral/answers/838950-return-the-number-of-rows-of-an-array

评论： Riley 2021-5-25

采纳的回答： Stephan

Hi, I just started using Matlab and is confused on how to extract the row indices/ row numbers.

For example, I have a function A:

A = [10 20 30 40 50 60 70 80 90 100]

I wanted to extract the row which has elements less than 50 so it will give

B= [1 2 3 4] (from row 1 to 4)

May I know how to do this? Any help and advice is greatly appreciated

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Stephen23 2021-5-25

You seem to have confused rows with columns:

Your example A has only one row and ten columns, whereas your example B has one row and five columns.

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Stephan 2021-5-25

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A = [10 20 30 40 50 60 70 80 90 100] 
A = 1×10
    10    20    30    40    50    60    70    80    90   100
B = A(A<50)
B = 1×4
    10    20    30    40

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Stephan 2021-5-25

A = [10 20 30 40 50 60 70 80 90 100] 
A = 1×10
    10    20    30    40    50    60    70    80    90   100
[row, col] = find(A<50)
row = 1×4
     1     1     1     1
col = 1×4
     1     2     3     4