How can I delete the rows of a matrix in matlab under a given condition

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Sky Scrapper 2018-11-14

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编辑： madhan ravi 2018-11-23

Hello everybody,

I have a matrix which has 10118 rows and 14 columns. I would like to delete the number of rows having values greater than 100. How can I do this?

Thanks in advance!

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madhan ravi 2018-11-14

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编辑：madhan ravi 2018-11-23

在 MATLAB Online 中打开

EDITED

%Numbers greater than 100
idx = matrix > 100;
matrix ( ~ ( sum ( idx , 2) == 0 ) , : ) = []
%__________________________
%Numbers lesser than 100
idx = matrix < 100;
matrix ( sum ( idx , 2 ) ~= 0 , : ) = []

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Stephen23 2018-11-23

编辑：Stephen23 2018-11-23

This code, although convoluted, will remove rows with any value greater than 100:

idx = matrix < 100;
matrix ( ~ ( sum ( idx , 2) == 0 ) , : ) = []

But what is this going to do?:

idx = matrix < 100;
matrix ( sum ( idx , 2 ) == size ( matrix , 2 ) , : ) = []

madhan ravi 2018-11-23

编辑：madhan ravi 2018-11-23

@Skyscraper: yes because if any of the numbers in a matrix is less than 100 the whole row is removed, the matrix which you gave contains numbers less than 100 in each row.

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Stephen23 2018-11-23

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编辑：Stephen23 2018-11-23

@Sky Scrapper: the standard MATLAB practice is to use any:

>> A = [110,0,10,70,15;100,30,50,20,9;50,-150,95,65,7]
A =
   110     0    10    70    15
   100    30    50    20     9
    50  -150    95    65     7
>> B = A(~any(abs(A)>100,2),:) % create a new array B,
B =
   100    30    50    20     9
>> A(any(abs(A)>100,2),:) = [] % or delete rows from A.
A =
   100    30    50    20     9