I'm saving a 1x50 array in a variable in a netCDF file and this operation is done every ~10sec.
I would like also to save matlab'time datestr(now) (YYYY-MM-DDTHH:MM:SS).
How should I do ?
I tried to store the date (datestr(now)) in a time variable without success.
Kind regards,
To store a variable in your workspace to a .mat file, you can use this:
variable = 1; % Variable to store.
fileName = ['fileName - ', datestr(now, 'yyyy-mm-dd HH.MM.SS'), '.mat'];
save(fileName, '-mat', 'variable');
Note that a ':' in the date string will make the save() function throw an error.
I finaly succeed in store time in my netCDF file.
1. I defined a 'time' dimension
2. I defined a dimension for my 1x50 value
then I wrote my data
ncwrite(ncfilename, 'data',myData.',[1 i]);
ncwrite(ncfilename, 'time',myData_triggertime,i);
where myData (my 1x50 array), myData_triggertime (=datestr(now)) are updated at each acquisition loop and i incremented at each loop.
kind regards
Related
I have a model using a timeTable which represents a variable evolution. I would like to initialize a subcomponent's parameter with the first value of the table (time = 0 second).
The table's values are read from a .txt file. The idea would be to have a command as follow :
parameter Real InitialValue = timeTable.y[2](for timeTable.y[1] = 0)
Is there a command to do so ?
In some cases another option is to initialize the parameter at the output value of that table-component when starting the simulation:
model Demo
Modelica.Blocks.Sources.TimeTable timeTable(table=[0,1; 2,3]);
parameter Real initialValue(fixed=false);
initial equation
initialValue = timeTable.y;
end Demo;
This works for all variants in the same way, but only for the initial value. It is triggered by having fixed=false for a parameter and then giving an initial equation for it.
The solution depends on the block you are using and how the data is defined. Note that there is no easy solution for .txt files, so I recommend using .mat files instead.
1. Data from model
If you don't read from a file it is quite easy.
The data is stored as matrix in the parameter table and we can use array indexing to access it:
model Demo
Modelica.Blocks.Sources.TimeTable timeTable(table=[0,1; 2,3]);
parameter Real initialValue = timeTable.table[1, 2];
end Demo;
This works for both, the Modelica.Blocks.Sources.TimeTable and the CombiTimeTable found in the same package.
2. Data from .mat file
The MSL provides functions to access .mat files. You have to get the table size before you can read the data.
See the code below how this can be done.
model Demo2
import Modelica.Utilities.Streams.{readMatrixSize, readRealMatrix};
parameter String fileName = "C:/tmp/table.mat";
parameter String tableName = "tab1";
parameter Real initialValue = (readRealMatrix(fileName=fileName, matrixName=tableName, nrow=matrixSize[1], ncol=matrixSize[2]))[1, 2];
Modelica.Blocks.Sources.CombiTimeTable combiTimeTable(
tableOnFile=true,
tableName=tableName,
fileName=fileName)
annotation (Placement(transformation(extent={{-10,-10},{10,10}})));
protected
final parameter Integer matrixSize[2] = readMatrixSize(fileName, tableName);
end Demo2;
Note that we don't store the whole table in a variable. Instead,
we read it and access the element of intereset with [1, 2]. This requires putting brackets around the function call.
I have an FFT and I want to save this to .mat file and then read it from that .mat file. I want to use my loaded data for a division. Here is my code
save ('file_fft','a_fft');
b = load ('file_fft');
c = abs (d_fft) ./ abs (b);
In my command window I see that
b = file_fft [4000 * 1 double].
And then I get error message
'Undefined function 'abs' for input arguments of type 'struct''
I tried after deleting abs. I got this error
'Undefined function 'rdivide' for input arguments of type 'struct''
Does anybody have any idea that why it is not working and how i can solve it?
Check the documentation for the load function:
S = load(___) loads data into S, using any of the input arguments in
the previous syntax group.
If filename is a MAT-file, then S is a structure array.
If filename is an ASCII file, then S is a double-precision array
containing data from the file.
So b is a structure and as suggested in the comment, you need to access the data as abs(b.a_fft).
The problem is that load() already creates the file structure that is inside the .mat file. When you assign file_fft with load, it creates a struct.
From the documentation of load():
S = load(_) loads data into S, using any of the input arguments in
the previous syntax group.
If filename is a MAT-file, then S is a structure array.
Edit:
I got sniped :-P
Here's another working example of code:
save ('file_fft','a_fft');
load ('file_fft');
c = abs (d_fft) ./ abs (file_fft);
I have data stored in the .tdms format, gathering the data of many sensors, measured every second, every day. A new tdms file is created every day, and stored in a folder per month. Using the convertTDMS function, I have converted these tdms files to mat files.
As there are some errors in some of the measurements(e.g. negative values which can not physically occur), I have performed some corrections by loading one mat file at a time, do the calculations and then save the data into the original .mat file.
However, when I try to do what I described above in a loop (so: load .mat in folder, do calculations on one mat file (or channel therein), save mat file, repeat until all files in the folder have been done), I end up running into trouble with the limitations of the save function: so far I save all variables (or am unable to save) in the workspace when using the code below.
for k = 1:nFiles
w{k,1} = load(wMAT{k,1});
len = length(w{k,1}.(x).(y).(z));
pos = find(w{k,1}.(x).(y).(z)(1,len).(y)<0); %Wind speed must be >0 m/s
for n = 1:length(pos)
w{k,1}.(x).(y).(z)(1,len).(y)(pos(n)) = mean([w{k,1}.(x).(y).(z)(1,len).(y)(pos(n)+1),...
w{k,1}.(x).(y).(z)(1,len).(y)(pos(n)-1)],2);
end
save( name{k,1});
%save(wMAT{k,1},w{k,1}.(x),w{k,1}.ConvertVer,w{k,1}.ChanNames);
end
A bit of background information: the file names are stored in a cell array wMAT of length nFiles in the folder. Each cell in the cell array wMAT stores the fullfile path to the mat files.
The data of the files is loaded and saved into the cell array w, also of length nFiles.
Each cell in "w" has all the data stored from the tdms to mat conversion, in the format described in the convertTDMS description.
This means: to get at the actual data, I need to go from the
cell in the cell array w{k,1} (my addition)
to the struct array "ConvertedData" (Structure of all of the data objects - part of convertTDMS)
to the struct array below called "Data" (convertTDMS)
to the struct array below called "MeasuredData" (convertTDMS) -> at this level, I can access the channels which store the data.
to finally access/manipulate the values stored, I have to select a channel, e.g. (1,len), and then go via the struct array to the actual values (="Data"). (convertTDMS)
In Matlab format, this looks like "w{1, 1}.ConvertedData.Data.MeasuredData(1, len).Data(1:end)" or "w{1, 1}.ConvertedData.Data.MeasuredData(1, len).Data".
To make typing easier, I took
x = 'ConvertedData';
y = 'Data';
z = 'MeasuredData';
allowing me to write instead:
w{k,1}.(x).(y).(z)(1,len).(y)
using the dot notation.
My goal/question: I want to load the values stored in a .mat file from the original .tdms files in a loop to a cell array (or if I can do better than a cell array: please tell me), do the necessary calculations, and then save each 'corrected' .mat file using the original name.
So far, I have gotten a multitude of errors from trying a variety of solutions, going from "getfieldnames", trying to pass the name of the (dynamically changing) variable(s), etc.
Similar questions which have helped me get in the right direction include Saving matlab files with a name having a variable input, Dynamically Assign Variables in Matlab and http://www.mathworks.com/matlabcentral/answers/4042-load-files-containing-part-of-a-string-in-the-file-name-and-the-load-that-file , yet the result is that I am still no closer than doing manual labour in this case.
Any help would be appreciated.
If I understand your ultimate goal correctly, I think you're pretty much there. I think you're trying to process your .mat files and that the loading of all of the files into a cell array is not a requirement, but just part of your solution? Assuming this is the case, you could just load the data from one file, process it, save it and then repeat. This way you only ever have one file loaded at a time and shouldn't hit any limits.
Edit
You could certainly make a function out of your code and then call that in a loop, passing in the file name to modify. Personally I'd probably do that as I think it's neater solution. If you don't want to do that though, you could just replace w{k,1} with w then each time you load a file w would be overwritten. If you wanted to explicitly clear variables you can use the clear command with a space separated list of variables e.g. clear w len pos, but I don't think that this is necessary.
i'm trying to save values of iterations in a loop. After this function, they will execute other functions before coming to the next iteration. But the problem i'm facing is, it overwrites them and bcomes 000000. Only the last iteration values are seen. How can i fix it ? Is there a way not to use the same variable and save them ? i read about append but will have to use different var name n is not really nice to do so.
function DistanceMatrix(iteration,distance_row)
load('data.mat','oridata')
load('centroids.mat','centroids')
for i = distance_row:(distance_row+3)
for j=1:300 %no.genes
total=0;
for k=1:6
total=total+((oridata(j,k)- centroids(i,k))^2);
end
DistMatrix_Val(i,j)=sqrt(total);
end
end
save('DistanceMatrix.mat','DistMatrix_Val')
DistMatrix_Val;
GroupMatrix(iteration,distance_row)
end
This is the output. I WOULD LIKE TO STORE ALL ITERATION's value and not overwrite them. Can any1 help ?
OK. Use
load('DistanceMatrix.mat','DistMatrix_Val')
or
persistent DistMatrix_Val
just before the first load command you showed to us.
I think this is what you should do:
functon DistanceMatrix = DistanceMatrix(iteration,distance_row)
Rather than saving the variable at the end of the function, you return it.
After returning it you can include the variable in a bigger variable (for example a three dimensional Nx4x300 matrix)
If neccesary you can then save it at the end.
I got this .nc file. However, when I read the file like this
ncid = netcdf.open(ncfile)
It gives me only a number. It was supposed to contain some data. I am not sure what's wrong with it. Can anyone please provide some information?
According to the documentation, netcdf.open only returns the NetCDF ID, not the data:
ncid = netcdf.open(source) opens source, which can be the name of a
NetCDF file or the URL of an OPeNDAP NetCDF data source, for read-only
access. Returns a NetCDF ID in ncid.
You probably want to use ncread.
Note:
ncid = netcdf.open(ncfile)
Where ncid is a netCDF file identifier returned by netcdf.create or
netcdf.open.
Eg : In your Case
ncid=netcdf.open(ncfile,'NC_NOWRITE');
varidp=netcdf.inqVarID(ncid,'varname'); //returns varid
Eg : Official
This example opens the example netCDF file included with MATLAB®, example.nc, and uses several inquiry functions to get the ID of the first variable.
ncid = netcdf.open('example.nc','NC_NOWRITE');
% Get information about first variable in the file.
[varname, xtype, dimids, atts] = netcdf.inqVar(ncid,0);
% Get variable ID of the first variable, given its name
varid = netcdf.inqVarID(ncid,varname)
Ref:http://www.mathworks.in/help/matlab/ref/netcdf.inqvarid.html
Thanks