I have 2D data for 10x10 matrices, and it looks like this
here is the table
However, data is updating and append every dt calculation, therefore I would like to reorganize and write it for specific columns , you may see this table in link
I use normally those codes to write
t=t+dt;
if ss==2000
dlmwrite('d:\Model_Results_Theta.txt', Tnew,'-append');
ss=0;
end
Could you recommend me any different way to organize the data based on the specific rows and columns using the matlab codes? Thanks in advance !!
Related
I need your help again :). I'm trying to plot multiple lines for a very large dataset. To start easier, I divided the dataset to get a TABLE in Matlab that contains 6 columns, with the first column representing the date that I want on my x-axis. Now I want to plot the other columns (and in the original file are a lot more than 6 columns) on the y axis, using a for loop. I tried the following, with no success:
hold on
for i=2:1:6
plot(Doldenstock(:,1), Doldenstock(:,i));
end
hold off
As I understand this, this code would do exactly what I want for columns 2,3,4,5,6. However, I always get the same error code:
Error using tabular/plot
Too many input arguments.
Error in Plotting_bogeo (line 6)
plot(Doldenstock(:,1), Doldenstock(:,i));
Now, I don't know if maybe for loops like this don't work for tabes but only for arrays?
Thanks for your help in advance!
Cheers,
Tamara
The function plot(x) expect x to be a scalar, a vector, or a matrix. But in your case the input is a table, because accessing a table with parentheses return a table, which is not supported.
If you read the doc "how to access data in a table" you will figure out that you need to use curly brace {} to extract the raw data (in your case a 1D matrix).
So use:
plot(T{:,1},T{:,2})
Unfortunately I am not too tech proficient and only have a basic MATLAB/programming background...
I have several csv data files in a folder, and would like to make a histogram plot of all of them simultaneously in order to compare them. I am not sure how to go about doing this. Some digging online gave a script:
d=dir('*.csv'); % return the list of csv files
for i=1:length(d)
m{i}=csvread(d(i).name); % put into cell array
end
The problem is I cannot now simply write histogram(m(i)) command, because m(i) is a cell type not a csv file type (I'm not sure I'm using this terminology correctly, but MATLAB definitely isn't accepting the former).
I am not quite sure how to proceed. In fact, I am not sure what exactly is the nature of the elements m(i) and what I can/cannot do with them. The histogram command wants a matrix input, so presumably I would need a 'vector of matrices' and a command which plots each of the vector elements (i.e. matrices) on a separate plot. I would have about 14 altogether, which is quite a lot and would take a long time to load, but I am not sure how to proceed more efficiently.
Generalizing the question:
I will later be writing a script to reduce the noise and smooth out the data in the csv file, and binarise it (the csv files are for noisy images with vague shapes, and I want to distinguish these shapes by setting a cut off for the pixel intensity/value in the csv matrix, such as to create a binary image showing these shapes). Ideally, I would like to apply this to all of the images in my folder at once so I can shift out which images are best for analysis. So my question is, how can I run a script with all of the csv files in my folder so that I can compare them all at once? I presume whatever technique I use for the histogram plots can apply to this too, but I am not sure.
It should probably be better to write a script which:
-makes a histogram plot and/or runs the binarising script for each csv file in the folder
-and puts all of the images into a new, designated folder, so I can sift through these.
I would greatly appreciate pointers on how to do this. As I mentioned, I am quite new to programming and am getting overwhelmed when looking at suggestions, seeing various different commands used to apparently achieve the same thing- reading several files at once.
The function csvread returns natively a matrix. I am not sure but it is possible that if some elements inside the csv file are not numbers, Matlab automatically makes a cell array out of the output. Since I don't know the structure of your csv-files I will recommend you trying out some similar functions(readtable, xlsread):
M = readtable(d(i).name) % Reads table like data, most recommended
M = xlsread(d(i).name) % Excel like structures, but works also on similar data
Try them out and let me know if it worked. If not please upload a file sample.
The function csvread(filename)
always return the matrix M that is numerical matrix and will never give the cell as return.
If you have textual data inside the .csv file, it will give you an error for not having the numerical data only. The only reason I can see for using the cell array when reading the files is if the dimensions of individual matrices read from each file are different, for example first .csv file contains data organised as 3xA, and second .csv file contains data organised as 2xB, so you can place them all into a single structure.
However, it is still possible to use histogram on cell array, by extracting the element as an array instead of extracting it as cell element.
If M is a cell matrix, there are two options for extracting the data:
M(i) and M{i}. M(i) will give you the cell element, and cannot be used for histogram, however M{i} returns element in its initial form which is numerical matrix.
TL;DR use histogram(M{i}) instead of histogram(M(i)).
I've imported the data of daily returns into a MatLab matrix using the importdata function:
19990104 0.0269360000000000
19990105 0.0170490000000000
...
I need to create a histogram of data in the second column. What's the best way to create a histogram of data in the second column? Do I need to assign types to columns separately?
Thank you for any suggestions.
I have a huge arrays in matlab that I am concatenating into a table and then I am dumping that table into a .csv file. Shown below:
% Create manipulated results with noise table
busResultNoise = array2table(busResult_arr); %This command converts the array into a table
% Horizontally concatenate timestamp table and bus data measurements with
% noise table
busResultNoise = horzcat(timeStamp_bus_tab,busResultNoise); %adds the timestamps array
% Assign same variable to busResultNoise as in busResult table
busResultNoise.Properties.VariableNames= busResult.Properties.VariableNames;%adds column names
%Export csv
writetable(busResultNoise,'BusDataWithNoise.csv');
This works great especially if the table/array is small. Is there a faster way to write to .csv file (or may be a text file with commas in it)? I am not required to form a table as shown above but I am doing so because I thought adding timestamp column and adding column names is easier. Please suggest if there is a faster way to do it because this code chokes if the array/table is really large.
I'm currently writing a piece of code which is supposed to import text files using importdata and count the number of columns, i thought the cols() function would suffice for this, but it seems that all the imported data is stored as a double, meaning I can't perform this operation.
M=importdata('title');
numcols=cols(M.data);
Am I doing something wrong? I thought the data fromthe text file would be stored in a matrix/array?
Cols is a specific function for use in the database toolbox.
You probably just want to use the size function. EG:
size(M.data,2); %Returns number of columns
FYI
size(M.data, 1); %Returns number of rows.