I need to import data from a square region (10 by 10 cells) on an Excel sheet into Matlab.
All data in the region are numerical, but some outer rows and columns of the region are empty.
In Matlab I still want to have a 10 by 10 matrix of doubles with NaNs in places where there are empty cells in Excel (also in outer rows and columns).
If I use xlsread then empty outer rows and columns are automatically truncated.
Needless to say that all should be done automatically without the knowledge how many empty outer rows and columns are there.
How can I do this?
Let's say your 10 by 10 spreadsheet's first row and column and last row and column are empty (like this). Using:
[num,txt,raw] = xlsread('myfile.xlsx',1,'A1:J10'); % Read input.
will return:
num 8x8 double
txt 0x0 cell
raw 10x10 cell
In num, non-scalar leading rows and columns are automatically truncated, while in txt any numerical values are omitted. However, raw contains all information, so it can be used to extract the numerical values:
raw(cellfun(#ischar,raw)) = {NaN}; % Set non-scalar values to missing.
A = cell2mat(raw); % Convert to matrix.
Related
I have the following table: Table
Columns 'L' and 'U' if the table consist of cells that contain object names that correspond to the headers in columns 4-281. Example
Goal: For every date verify what objects are in 'L' (respectively 'U') and sum the aggregate of those objects' 4-point trailing moving sum and its standard deviation (going up in the table!) and store it in a new variable, e.g. LSum and LStd for 'L' as well as USum and UStd for 'U'. For dates with insufficient values, e.g. 15-Jul-2016 with only 3 instead of 4 time steps ahead, return NaN's.
How I would start:
for row=1:size(ABC,1)
row_values = ABC{row,:};
row_values = row_values(4:end);
% How to make the loop for columns L and U where there are multiple objects in one cell?
% How can I use 'movsum' and 'movstd' here to calculate values vertically going up?
end;
Thanks a lot for your help!
Maybe you could use the functions cell2mat and cellfun to achieve your goal.
With these functions you can:
Convert your cell matrix to a double matrix in order to perform (cell2mat)
Perform a certain operation on all cell elements (cellfun)
I am having matrix with approx 3000 rows(changing) and 3 columns.
I have count of both rows and columns.
I am trying to plot the graph:
x=1:3000;
plot(matrix(x,1))
is there any way that I can include all rows in the plot instruction itself so that I can remove 'x=1:3000' ?
Also, I want to divide, 1st column of matrix which have 3000 rows into another matrix of 3 columns each with 1000 rows. Any specific instruction for this ?
I have made for loop for this and then i am placing individually the elements in the new array. But its taking long time.
As to the plotting issue, using the colon operator will plot all rows for your desired column:
plot(matrix(:,1));
EDIT: You mentioned you were a beginner. In case you haven't seen the colon operator used like this before, a colon operator all by itself when indexing into a matrix essentially means "all __", either "all rows" if in the first position or "all columns" if in the second position.
As for the second question, of splitting one column into a new matrix with multiple columns, you can use the reshape() function, which takes the input matrix to be reshaped and a number of output rows and columns. For example, to split the first column of matrix into 3 columns and put them into newMatrix, use the following:
newMatrix = reshape(matrix(:,1),[],3);
Note that the above code uses [] in the second argument (the number of rows argument) to mean "automatically determine number of rows".This is automatically determined based on the number of columns, which is defined in the third argument here as 3. The reshape function requires that the number of output rows * output columns be equal to input rows * input columns. So in the above case this will only work if the starting matrix has a number of rows which is divisible by 3.
I have an image converted with the use of im2cal in an array of 9 rows and 3867208 columns and i want to count how many times a vector containing a mask is equal to each column of the image without using for loops in matlab.Do you have any ideas?
I have 60 values in a cell matrix from a .csv file which are stored in column 15 from rows 38556-38616
I want to copy that range of values to a regular numerical 60x1 matrix in a variable Value
Here is what I tried:
Values(60,1) = data2{38556:38616,15};
It only copies 1 value from data2 and the rest of values from rows 1-59 are 0. How can I copy
those values to Value in the same order they are in the file? data2 is the cell matrix storing .csv file values.
Image of data2:
Either
Values(1:61,1) = cell2mat(data2(38556:38616,15));
or just
Values = [data2{38556:38616,15}]';
The problem was that you tried to store 61 values into just one matrix element.
Incidentally, if you don't need the full contents of the csv file, just a subset, and the contents you are reading in are numeric, you can take this directly from the file using dlmread. For example:
values = dlmread('data.csv',',',[38555 14 38615 14]);
The numeric values are starting and ending positions: [R1 C1 R2 C2]. dlmread starts counting at zero for R/C values. You can also use spreadsheet style instead, i.e. 'A4..G6' or in your case I think it would be 'O38556..O38616'.
i've got a cell array full of numbers, with 44 rows and different column length in each row
how could i calculate the number of columns in each row?(the columns which their contents are not empty)
i've used 2 different ways which both of them where wrong
the 1st one:
%a is the cell array
s=length(a)
it gives 44 which is the number of rows
the 2nd one
[row, columms]=size(a)
but it doesn't work either cause the number of columns is different in each row.
at least i mean the number of columns which are not empty
for example i need the number of columns in row one which it is 43(a{1 1:43}) but it gives the number of columns for each elements like a{1,1} which is 384 or a{1,2},a{1,3} and so on
You need to access each member of the cell array separately, you are looking for the size of the data contained in the cell - the cell is the container. Two methods
for loop:
cell_content_lengths=zeros(1,length(a));
for v=1:length(a)
cell_content_lengths(v)=length(a{v});
end
cellfun:
cell_content_lengths=cellfun(#length,a);
Any empty cells will just have length 0. To extend the for-loop to matrices is trivial, and you can extend the cellfun part to cells containing matrix by using something like this, if you are interested:
cell_content_sizes=cell2mat(cellfun(#length,a,'uniformoutput',false));
(Note for the above, each element of a needs to have the same dimension, otherwise it will give errors about concatenating different size matrices)
EDIT
Based on your comment I think I understand what you are looking for:
non_empty_cols = sum(~cellfun(#isempty,a),2);
With thanks to #MZimmerman6 who understood it before me.
So what you're really asking, is "How many non-empty elements are in each row of my cell array?"
filledCells = ~cellfun(#isempty,a);
columns = sum(filledCells,2);