MATLAB: Delete specific rows from a cell array

cell arrayremovespecific

Hello everyone, i have a cell array just like this:

value     Class
1200     'Unknown - State'
1700     'Rest'
1600     'Unknown - State'
2100     'City'

How i'm going to remove the rows whose class is 'Unknown-State' so my result cell array woulb be like this:

Value     Class
1700     'Rest'
2100     'City'

Best Answer

Assuming your cell array is name "C", then

removeIndex = strcmp(C(:,2),'Unknown - State');
C(removeIndex,:) = [];

If you don't know ahead of time that the class is the second column, then you could find the class column number using

classIdx = find(strcmp(C(1,:),'Class'))

Related Solutions

MATLAB: Rows mean collapse in big matrix

If the number of rows of M was an integer multiple of N then this would be easy to achieve by simply reshaping the matrix M. Because your data does not fit this we have to take into account that there may be from 1 to N last rows to be "collapsed" together. This can be achieved using mat2cell to split the matrix into groups, and then performing the mean inside a cellfun call:

% Number of rows to "collapse" together:
N = 3;
% Your data:
M = [...
    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    5];
% vector of row counts:
row = N*ones(1,ceil(size(M,1)/N));
row(end) = mod(size(M,1)-1,N)+1;
% scalar of column count:
col = size(M,2);
% split data into cell, with the specified rows and columns in groups:
C = mat2cell(M,row,col);
% calculate mean of each group and concatenate back into one matrix:
out = cell2mat(cellfun(@(m)mean(m,1),C,'UniformOutput',false));

and the output in the command window:

>> out
out =
    64.667       86.667           32           14       17.667       64.667       61.667           57           64       42.667
    62.667           68           40       35.333           34       54.333       59.667       56.667           52       42.333
    37.333       7.6667           63       93.333       88.667       37.333       32.667           38       43.333       63.667
        11           18          100           77           84           36           43           50           27            5

MATLAB: Cell2Mat for cells with different dimensions

Try this:

C={[21  24  47  89  57]' , [24  21]' , [16  87  47  89  90  99  182]'}; 
rows = cellfun(@numel,C);
cols = size(C,2);
A = zeros(max(rows),cols);
for k = 1:cols
    A(1:rows(k),k) = C{k};
end

producing:

A
A =
    21    24    16
    24    21    87
    47     0    47
    89     0    89
    57     0    90
     0     0    99
     0     0   182

EDIT — (16 Aug 2020 at 21:31)

Corrected the preallocation of ‘A’ to use the previously calculated values of ‘rows’ and ‘cols’. Code otherwise unchanged.

Best Answer

Related Solutions

MATLAB: Rows mean collapse in big matrix

MATLAB: Cell2Mat for cells with different dimensions

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