MATLAB: How to find frequency of occurence of a specific element in a matrix per column?

matrixmatrix arraymatrix manipulation

Sir i have a matrix say A=(0.1 80 55 0 55 0 55; 0.5 88 0 55 55 0 55; 2 89 55 0 55 55 0; 2.5 90 55 55 55 55 55; ……………….; ……………….; 40 95 55 55 0 55 0) Now i have to find the frequency of occurrence of 55 from column3:7 for a particular range of column 1 say 0-2.5. the fist and second column will have the average value and the others will have only the frequency of 55 so that i will get a result matrix R of dimension 1*7. would you help me please to do this???? thanks

Best Answer

tf = A(:,1) >= 0 & A(:,1) <= 2.5  % true, when within range
tmp = A(tf,3:7)
N55percolumn = sum(tmp==55,1)

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MATLAB: How to select specific values in a matrix

>> a = magic(10)
a =
      92    99     1     8    15    67    74    51    58    40
      98    80     7    14    16    73    55    57    64    41
       4    81    88    20    22    54    56    63    70    47
      85    87    19    21     3    60    62    69    71    28
      86    93    25     2     9    61    68    75    52    34
      17    24    76    83    90    42    49    26    33    65
      23     5    82    89    91    48    30    32    39    66
      79     6    13    95    97    29    31    38    45    72
      10    12    94    96    78    35    37    44    46    53
      11    18   100    77    84    36    43    50    27    59
>> a(1,4)
ans =
       8
>> a(4,7)
ans =
      62
>> a(3,5:end)
ans =
      22    54    56    63    70    47

MATLAB: I don’t understand about this row and column?

Well the first one starts at row (or column) 8 while the second one starts at 1. There are some other differences but you can just print them out to see:

N=8
L=512
i= N:N:L-N
j = 1:L
i= 1:L
j= N:N:L-N

Then look in the command window to see what they are.

Best Answer

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MATLAB: How to select specific values in a matrix

MATLAB: I don’t understand about this row and column?

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