I have a matlab code which is for printing a cell array to excel. The size of matrix is 50x13.
The row 1 is the column names.
Column 1 is dates and rest columns are numbers.
The dateformat being defined in the code is:
dFormat = struct;
dFormat.Style = struct( 'NumberFormat', '_(* #,##0.00_);_(* (#,##0.00);_(* "-"??_);_(#_)' );
dFormat.Font = struct( 'Size', 8 );
Can someone please explain me what the dFormat.Style code means ?
Thanks
The first line creates an empty struct (struct with no fields) called dFormat. A structure can contain pretty much anything in one of its fields, including another structure. The second line adds a field called 'Style' to the dFormat struct and sets it equal to another struct with a field called 'NumberFormat'. The 'NumberFormat' field is set equal to that long string of characters. You now have a structure of structures. The third line is similar to the second.
Note that the first line isn't really necessary unless dFormat already exists and it needs to be "zeroed out" as dFormat.Style with create it implicitly. However, using the struct function can make code more readable in some cases as objects use a similar notation for access methods and properties. In other words, all of your code could be replaced with:
dFormat.Style.NumberFormat = '_(* #,##0.00_);_(* (#,##0.00);_(* "-"??_);_(#_)';
dFormat.Font.Size = 8;
See this video from the MathWorks for more details and this list of helpful structure functions and examples.
#horchler already elaborated on structs, but I imagine you may actually be more interested in the content of this structs Style field.
In case you are solely interested in _(* #,##0.00_);_(* (#,##0.00);_(* "-"??_);_(#_), that does not really look like something MATLAB related to me.
My best guess is that this code is used to later feed some other program, for examle to build an excel file.
Related
I have large data sets which i want to work with in matlab.
I have a struct called Trail containing serveral structures called trail1, trail2 ...
which then contain several matrices. I now want to add another point to for instance trail1
I can do that with Trail.trail1.a2rotated(i,:) = rotpoint'; the problem is that i have to do it in a loop where the trail number as well as the a2rotated changes to e.g. a3rot...
I tired to do it like that
name ="trail"+num2str(z)+".a2rotated"+"("+i+",:)";
name = convertStringsToChars(name);
Trail.(name) = rotpoint'
But that gives me the error: Invalid field name: 'trail1.a2rotated(1,:)'.
Does someone have a solution?
The name in between brackets after the dot must be the name of a field of the struct. Other indexing operations must be done separately:
Trail.("trail"+z).a2rotated(i,:)
But you might be better off making trail(z) an array instead of separate fields with a number in the name.
I'm working with .mat files which are saved at the end of a program. The command is save foo.mat so everything is saved. I'm hoping to determine if the program changes by inspecting the .mat files. I see that from run to run, most of the .mat file is the same, but the field labeled __function_workspace__ changes somewhat.
(I am inspecting the .mat files via scipy.io.loadmat -- just loading the files and printing them out as plain text and then comparing the text. I found that save -ascii in Matlab doesn't put string labels on things, so going through Python is roundabout, but I get labels and that's useful.)
I am trying to determine from where these changes originate. Can anyone explain what __function_workspace__ contains? Why would it not be the same from one run of a given program to the next?
The variables I am really interested in are the same, but I worry that I might be overlooking some changes that might come back to bite me. Thanks in advance for any light you can shed on this problem.
EDIT: As I mentioned in a comment, the value of __function_workspace__ is an array of integers. I looked at the elements of the array and it appears that these numbers are ASCII or non-ASCII character codes. I see runs of characters which look like names of variables or functions, so that makes sense. But there are also some characters (non-ASCII) which don't seem to be part of a name, and there are a lot of null (zero) characters too. So aside from seeing names of things in __function_workspace__, I'm not sure what that stuff is exactly.
SECOND EDIT: I found that after commenting out calls to plotting functions, the content of __function_workspace__ is the same from one run of the program to the next, so that's great. At this point the only difference from one run to the next is that there is a __header__ field which contains a timestamp for the time at which the .mat file was created, which changes from run to run.
THIRD EDIT: I found an article, http://nbviewer.jupyter.org/gist/mbauman/9121961 "Parsing MAT files with class objects in them", about reverse-engineering the __function_workspace__ field. Thanks to Matt Bauman for this very enlightening article and thanks to #mpaskov for the pointer. It appears that __function_workspace__ is an undocumented catch-all for various stuff, only one part of which is actually a "function workspace".
1) Diffing .mat files
You may want to take a look at DiffPlug. It can do diffs of MAT files and I believe there is a command line interface for it as well.
2) Contents of function_workspace
SciPy's __function_workspace__ refers to a special variable at the end of a MAT file that contains extra data needed for reference types (e.g. table, string, handle, etc.) and various other stuff that is not covered by the official documentation. The name is misleading as it really refers to the "Subsystem" (briefly mentioned in the official spec as an offset in the header).
For example, if you save a reference type, e.g., emptyString = "", the resulting .mat will contain the following two entries:
(1) The variable itself. It looks sort of like a UInt32 matrix, but is actually an Opaque MCOS Reference (MATLAB Class Object System) to a string object at some location in the subsystem.
[0] Compressed (81 bytes, position = 128)
[0] Matrix (144 bytes, position = 0)
[0] UInt32[2] = [17, 0] // Opaque
[1] Int8[11] = ['emptyString'] // Variable Name
[2] Int8[4] = ['MCOS'] // Object Type
[3] Int8[6] = ['string'] // Class Name
[4] Matrix (72 bytes, position = 72)
[0] UInt32[2] = [13, 0] // UInt32
[1] Int32[2] = [6, 1] // Dimensions
[2] Int8[0] = [''] // Variable Name (not needed)
[3] UInt32[6] = [-587202560, 2, 1, 1, 1, 1] // Data (Reference Target)
(2) A UInt8 matrix without name (SciPy renamed this to __function_workspace__) at the end of the file. Aside from the missing name it looks like a standard matrix, but the data is actually another MAT file (with a reduced header) that contains the real data.
[1] Compressed (251 bytes, position = 217)
[0] Matrix (968 bytes, position = 0)
[0] UInt32[2] = [9, 0] // UInt8
[1] Int32[2] = [1, 920] // Dimensions
[2] Int8[0] = [''] // Variable Name
[3] ... 920 bytes ... // Data (Nested MAT File)
The format of the data is unfortunately completely undocumented and somewhat of a mess. I could post the contents of the Subsystem, but it gets somewhat overwhelming even for such a simple case. It's essentially a MAT file that contains a struct that contains a special variable (MCOS FileWrapper__) that contains a cell array with various values, including one that magically encodes various Object Properties.
Matt Bauman has done some great reverse engineering efforts (Parsing MAT files with class objects in them) that I believe all supporting implementations are based on. The MFL Java library contains a full (read-only) implementation of this (see McosFileWrapper.java).
Some updates on Matt Bauman's post that we found are:
The MCOS reference can refer to an array of handle objects and may have more than 6 values. It contains sizing information followed by an array of indices (see McosReference.java).
The Object Id field looks like a unique id, but the order seems random and sometimes doesn't match. I don't know what this value is, but completely ignoring it seems to work well :)
I've seen Segment 5 populated in .fig files, but I haven't been able to narrow down what's in there yet.
Edit: Fyi, once the string object is correctly parsed and all properties are filled in, the actual string value is encoded in yet another undocumented format (see testDoubleQuoteString)
I'm relatively new to matlab and would really appreciate any help.
Currently, I have a function (we'll call it readf) that reads in data from a single ascii file into a struct of multiple fields (we'll call it cdata).
names = cellstr(char('A','B','C','D','E','F','G'));
cdata = readf('filestring','dataNames',names);
The function works fine and gives me the correct output of a struct with these field names, with the value of each field name being a cell array of the corresponding data.
My task is to create a for loop that uses this readf function to read in a folder of these ascii files at once. I'm trying to work it so that the for loop creates a struct with an index of the different cdata structs. After trying a few different methods, I am stumped.
This is what I have so far.
files = struct2cell(dir('folderstring')); %creates a cell array of the names of the files withing the folder
for ii=length(files);
cdata(ii) = readf([folderstring,files(1,1:ii),names],'dataName',names);
end;
This is currently giving me the following error.
"Error using horzcat
Dimensions of matrices being concatenated are not consistent."
I am not sure what is wrong. How can I fix this code so i can read in all the data from a folder at once??? Is there a better and more efficient way to do this than making an index to this struct? Perhaps a cell array of different structures or even a structure of nested structures? Thanks!
Change:
for ii=length(files);
cdata(ii) = readf([folderstring,files(1,1:ii),names],'dataName',names);
end;
To:
for ii=1:length(files); % CHECK to make sure length(files) is giving you the right number
cdata(ii) = readf([folderstring,files{ii},names],'dataName',names);
end;
% CHECK files{ii}, with 1,2,3 etc. is giving you the correct file name.
MATLAB's methodsview tool is handy when exploring the API provided by external classes (Java, COM, etc.). Below is an example of how this function works:
myApp = actxserver('Excel.Application');
methodsview(myApp)
I want to keep the information in this window for future reference, by exporting it to a table, a cell array of strings, a .csv or another similar format, preferably without using external tools.
Some things I tried:
This window allows selecting one line at a time and doing "Ctrl+c Ctrl+v" on it, which results in a tab-separated text that looks like this:
Variant GetCustomListContents (handle, int32)
Such a strategy can work when there are only several methods, but not viable for (the usually-encountered) long lists.
I could not find a way to access the table data via the figure handle (w/o using external tools like findjobj or uiinspect), as findall(0,'Type','Figure') "do not see" the methodsview window/figure at all.
My MATLAB version is R2015a.
Fortunately, methodsview.m file is accessible and allows to get some insight on how the function works. Inside is the following comment:
%// Internal use only: option is optional and if present and equal to
%// 'noUI' this function returns methods information without displaying
%// the table. `
After some trial and error, I saw that the following works:
[titles,data] = methodsview(myApp,'noui');
... and returns two arrays of type java.lang.String[][].
From there I found a couple of ways to present the data in a meaningful way:
Table:
dataTable = cell2table(cell(data));
dataTable.Properties.VariableNames = matlab.lang.makeValidName(cell(titles));
Cell array:
dataCell = [cell(titles).'; cell(data)];
Important note: In the table case, the "Return Type" column title gets renamed to ReturnType, since table titles have to be valid MATLAB identifiers, as mentioned in the docs.
I want to create a structure with a variable name in a matlab script. The idea is to extract a part of an input string filled by the user and to create a structure with this name. For example:
CompleteCaseName = input('s');
USER WRITES '2013-06-12_test001_blabla';
CompleteCaseName = '2013-06-12_test001_blabla'
casename(12:18) = struct('x','y','z');
In this example, casename(12:18) gives me the result test001.
I would like to do this to allow me to compare easily two cases by importing the results of each case successively. So I could write, for instance :
plot(test001.x,test001.y,test002.x,test002.y);
The problem is that the line casename(12:18) = struct('x','y','z'); is invalid for Matlab because it makes me change a string to a struct. All the examples I find with struct are based on a definition like
S = struct('x','y','z');
And I can't find a way to make a dynamical name for S based on a string.
I hope someone understood what I write :) I checked on the FAQ and with Google but I wasn't able to find the same problem.
Use a structure with a dynamic field name.
For example,
mydata.(casename(12:18)) = struct;
will give you a struct mydata with a field test001.
You can then later add your x, y, z fields to this.
You can use the fields later either by mydata.test001.x, or by mydata.(casename(12:18)).x.
If at all possible, try to stay away from using eval, as another answer suggests. It makes things very difficult to debug, and the example given there, which directly evals user input:
eval('%s = struct(''x'',''y'',''z'');',casename(12:18));
is even a security risk - what happens if the user types in a string where the selected characters are system(''rm -r /''); a? Something bad, that's what.
As I already commented, the best case scenario is when all your x and y vectors have same length. In this case you can store all data from the different files into 2 matrices and call plot(x,y) to plot each column as a series.
Alternatively, you can use a cell array such that:
c = cell(2,nufiles);
for ii = 1:numfiles
c{1,ii} = import x data from file ii
c{2,ii} = import y data from file ii
end
plot(c{:})
A structure, on the other hand
s.('test001').x = ...
s.('test001').y = ...
Use eval:
eval(sprintf('%s = struct(''x'',''y'',''z'');',casename(12:18)));
Edit: apologies, forgot the sprintf.