MATLAB: Mean of columns in a cell

MATLABmean of cells

I have a cell, wich looks like

'S001' [] ' M' 29 '70' '180' '118' '70'

'S002' [] 'F' 25 '58' '166' '130' '90'

'S003' [] 'M' 34 '62' '167' '120' '78'

'S004' [] 'F' 28 '72' '160' '118' '78'

…

Now I would like to have the means of each row. I try

cellfun(@mean,cell_formatiert(3:14,k))

I get an answer, but it is wrong.

Best Answer

Inputs:

cell_formatiert: your mxn cell array (presumably containing a mixture of numeric and character values, otherwise there is a much simpler answer).
rows : a vector of row numbers to include in the analysis
cols : a vector of column numbers to include in the analysis

cell_formatiert=  {
    'S001'	[]	'M'	29	'70'	'180'	'118'	'70'
    'S002'	[]	'F'	25	'58'	'166'	'130'	'90'
    'S003'	[]	'M'	34	'62'	'167'	'120'	'78'
    'S004'	[]	'F'	28	'72'	'160'	'118'	'78'};
% Select the columns to average for each row
cols = 4:8;
% Select the rows that should be analyzed
rows = 1:4;

Here we convert any character arrays that are within the cols and rows selection to numeric

% identify elements of the selected columns that are character arrays
charIdx = cellfun(@ischar,cell_formatiert);
charIdx(:,~ismember(1:size(cell_formatiert,2),cols)) = false; 
% Convert char arrays from chosen columns to numeric
cell_formatiert(charIdx) = num2cell(str2double(cell_formatiert(charIdx)));

If you want to comput the mean of each selected row, given the selected columns

% compute means per selected rows
mu = arrayfun(@(r)mean([cell_formatiert{r,cols}]),rows).';

mu is a vector of row-means, the same size as rows.

If you want to comput the mean of each selected column, given the selected rows

% compute means per selected columns
mu = arrayfun(@(c)mean([cell_formatiert{rows,c}]),cols);

mu is a vector of column-means, the same size as cols.

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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: Change of whole row in matrix

YourMatrix( any(YourMatrix<0, 2), :) = 0;

Best Answer

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MATLAB: Rows mean collapse in big matrix

MATLAB: Change of whole row in matrix

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