I am trying to add a column called "Lifespan" into the dataset in my workspace entitled "options_20020208".
I need to do this multiple times via a loop (Since there are multiple tables)
My problem is that I need to insert "Name" and have matlab process it as "options_20020208":
Name = options_20020208
Start = cellstr(Name(:,5))
End = cellstr(Name(:,3))
Start = datenum(Start)
End = datenum(End)
Lifespan = wrkdydif(Start,End)
Name.Lifespan = nominal(Lifespan)
I need to make it such that matlab reads the above code is read as :
Start = cellstr(options_20020208(:,5))
End = cellstr(options_20020208(:,3))
Start = datenum(Start)
End = datenum(End)
Lifespan = wrkdydif(Start,End)
options_20020208.Lifespan = nominal(Lifespan)
This is a fairly basic question, I know.. but I'm a newbie and not really sure how to approach it.
Any advice would help!!
Name_string = 'options_20020208';
eval([Name_string,'.Lifespan = nominal(Lifespan);']);
For a better answer, please show the exact line defining Name in your actual code.
Related
First sorry for basic questions..
What I've done was importing ".csv" to matlab using "readtable. But I don't have idea as to making this 367 different time series to be independent .mat files.
result = readtable('price.csv');
result is shown in image file to help understanding..
How could I make this process automatically?? Please help me..
result = readtable('price.csv');
for i = 1:2:734
M = rmmissing(result(:,[i,i+1]));
str = M.Properties.VariableNames(2);
% str{1}(regexp(str{1}, 'x')) = [];
name = str{1};
save(['C:\Users\bok\Desktop\mat\',name],'M');
end
I am beginner in MATLAB. I would like to load 200 image files (size 192x192) in a specific folder by using a for loop.
The image names are '1.png', '2.png', '3.png' and so on.
My code is as below.
list = dir('C:/preds/*.png');
N = size(list,1);
sum_image = zeros(192,192,200);
for i = 1:N
sum_image(:,:,i) = imread('C:/preds/i.png');
end
Which part should I change ?
I would probably do it like the code below:
You are currently getting the list of filenames then not really doing much with it. Iterating over the list is safer otherwise if there is a missing number you could have issues. Also, the sort maybe unnecessary depending if you image numbering is zero-padded so they come out in the correct order ... but better safe than sorry. One other small change initializing the array to size N instead of hard-coding 200. This will make it more flexible.
searchDir = 'C:\preds\';
list = dir([searchDir '*.png']);
nameList = {list.name}; %Get array of names
imNum = str2double(strrep(nameList,'.png','')); %Get image number
[~,idx] = sort(imNum); %sort it
nameList = nameList(idx);
N = numel(nameList);
sum_image = zeros(192,192,N);
for i=1:N
sum_image(:,:,i) = imread(fullfile(searchDir,nameList{i}));
end
I would suggest changing the line within the loop to the following:
sum_image(:,:,i) = imread(['C:/preds/', num2str(i), '.png']);
MATLAB treats the i in your string as a character and not the variable i. The above line of code builds your string piece by piece.
If this isn't a homework problem, the right answer to this question is don't write this as a for loop. Use an imageDatastore:
https://www.mathworks.com/help/matlab/ref/imagedatastore.html
ds = imageDatastore('C:/preds/');
sumImageCellArray = readall(ds);
sumImage = cat(3,sumImageCellArray{:});
I have some problem converting simples VB scripts (formating) into MATLAB:
VB script:
Range("A1").Select
Selection.Font.Italic = True
With Selection.Borders(xlEdgeBottom)
.LineStyle = xlContinuous
End With
I tried:
xlswrite('test.xls',1,'A1');
Excel = actxserver('Excel.Application');
Excel.Workbooks.Open('test.xls');
Range = Excel.Range('A1');
Range.Font.Italic = True; % Doesnt work
Range.Border.Item('xlEdgeRight').LineStyle = 1; % Doesnt work
Excel.Visible = 1;
Any workaround? Thanks
The problem is probably this line:
Range = Excel.Range('A1');
Your Excel object is an Application object, which doesn't have a Range property. The VBA example you follow uses a (IMHO) poor practice of using the global default objects that are only available within the context of the application itself. You need to grab a reference to the Workbook returned by this call:
Excel.Workbooks.Open('test.xls');
After that, you need to get the worksheet from it's indexed Worksheets property, then get the Range from that. Also, "xlEdgeRight" is an enumeration member so external calls have to use the integer values for them instead of a string. You can replace xlEdgeRight with 10.
I know next to nothing about Matlab, but this is what the more explicit code would look like in VBA:
Dim book As Workbook, sheet As Worksheet, rng As Range
Set book = Application.Workbooks.Open("test.xls")
Set sheet = book.Worksheets("Sheet1")
Set rng = sheet.Range("A1")
rng.Font.Italic = True
rng.Borders.Item(10).LineStyle = 1
You should be able to get it from there.
I am aware many of you will think this should be easily solvable. However, I have no clue about MATLAB.
Here goes my problem: when trying to execute the following example in the Command Window through the command
getLogReturnExcel('ALL.xls', {'ALL'}, 37000, 38000)
the cell-type error appears for this function. From what I understand however, when using {} the function should be grabbing the type inside {} (String in this case?) instead of the cell itself, which would be being grabbed if we were to use (), so there should be no error? Or is there something much more elementary that I might be overseeing? Thanks in advance for every bit of help; as you can tell I very much need it.
Cheers,
Ben
Here goes the function getLogReturnExcel:
function [logreturn, datearray] = getLogReturnExcel( datafilename, ticker, begindate, enddate )
[aanumber, aatext] = xlsread(datafilename);
aaticker = aatext(:,1);
aadate = aanumber(:,2);
aaret = zeros(length(aaticker),1);
aaret(1,1) = 0;
for i = 2:length(aaret)
aaret(i,1) = ln(aanumber(i,3))-ln(aanumber(i-1,3));
end
aadate = aadate(strcmp(aaticker,ticker));
aaret = aaret(strcmp(aaticker,ticker));
logreturn = aaret(aadate>=begindate & aadate<=enddate);
datearray = aadate(aadate>=begindate & aadate<=enddate);
return
The file 'ALL.xls' contains 3 columns, one with strings (the acronym for stocks) and two with numbers (I'm assuming double), one for the date in Excel-format and one with each day's stock standing.
The string can be obtained by using:
ticker{:}
or else the comparison in the lines
aadate = aadate(strcmp(aaticker,ticker));
aaret = aaret(strcmp(aaticker,ticker));
will be between strings and cell array.
Here is some documentation to access elements of a cell array.
I was just wondering if there is a clean way to store a matrix after each iteration with a different name? I would like to be able to store each matrix (uMatrix) under a different name depending on which simulation I am on eg Sim1, Sim2, .... etc. SO that Sim1 = uMatrix after first run through, then Sim2 = uMatrix after 2nd run through. SO that each time I can store a different uMatrix for each different Simulation.
Any help would be much appreciated, and sorry if this turns out to be a silly question. Also any pointers on whether this code can be cleaned up would be great too
Code I am using below
d = 2;
kij = [1,1];
uMatrix = [];
RLABEL=[];
SimNum = 2;
for i =1:SimNum
Sim = ['Sim',num2str(i)] %Simulation number
for j=1:d
RLABEL = [RLABEL 'Row','',num2str(j) ' '];
Px = rand;
var = (5/12)*d*sum(kij);
invLam = sqrt(var);
u(j) = ((log(1-Px))*-invLam)+kij(1,j);
uMatrix(j,1) = j;
uMatrix(j,2) = u(j);
uMatrix(j,3) = kij(1,j);
uMatrix(j,4) = Px;
uMatrix(j,5) = invLam;
uMatrix(j,6) = var;
end
printmat(uMatrix,'Results',RLABEL,'SECTION u kij P(Tij<u) 1/Lambda Var')
end
There are really too many options. To go describe both putting data into, and getting data our of a few of these methods:
Encode in variable names
I really, really dislike this approach, but it seems to be what you are specifically asking for. To save uMatrix as a variable Sim5 (after the 5th run), add the following to your code at the end of the loop:
eval([Sim ' = uMatrix;']); %Where the variable "Sim" contains a string like 'Sim5'
To access the data
listOfStoredDataNames = who('Sim*')
someStoredDataItem = eval(listOfStoredDataNames {1}) %Ugghh
%or of you know the name already
someStoredDataItem = Sim1;
Now, please don't do this. Let me try and convince you that there are better ways.
Use a structure
To do the same thing, using a structure called (for example) simResults
simResults.(Sim) = uMatrix;
or even better
simResults.(genvarname(Sim)) = uMatrix;
To access the data
listOfStoredDataNames = fieldnames(simResults)
someStoredDataItem = simResults.(listOfStoredDataNames{1})
%or of you know the name already
someStoredDataItem = simResults.Sim1
This avoids the always problematic eval statement, and more importantly makes additional code much easier to write. For example you can easily pass all simResults into a function for further processing.
Use a Map
To use a map to do the same storage, first initialize the map
simResults = containers.Map('keyType','char','valueType','any');
Then at each iteration add the values to the map
simResults(Sim) = uMatrix;
To access the data
listOfStoredDataNames = simResults.keys
someStoredDataItem = simResults(listOfStoredDataNames{1})
%or of you know the name already
someStoredDataItem = simResults('Sim1')
Maps are a little more flexible in the strings which can be used for names, and are probably a better solution if you are comfortable.
Use a cell array
For simple, no nonsense storage of the results
simResults{i} = uMatrix;
To access the data
listOfStoredDataNames = {}; %Names are Not available using this method
someStoredDataItem = simResults{1}
Or, using a slight level of nonesense
simResults{i,1} = Sim; %Store the name in column 1
simResults{i,2} = uMatrix; %Store the result in column 2
To access the data
listOfStoredDataNames = simResults(:,1)
someStoredDataItem = simResults{1,2}
Just to add to the detailed answer given by #Pursuit, there is one further method I am fond of:
Use an array of structures
Each item in the array is a structure which stores the results and any additional information:
simResults(i).name = Sim; % store the name of the run
simResults(i).uMatrix = uMatrix; % store the results
simResults(i).time = toc; % store the time taken to do this run
etc. Each element in the array will need to have the same fields. You can use quick operations to extract all the elements from the array, for example to see the timings of each run at a glance you can do:
[simResults.time]
You can also use arrayfun to to a process on each element in the array:
anon_evaluation_func = #(x)( evaluate_uMatrix( x.uMatrix ) );
results = arrayfun( anon_evaluation_func, simResults );
or in a more simple syntax,
for i = 1:length(simResults)
simResults(i).result = evaluate_uMatrix( simResults(i).uMatrix );
end
I would try to use a map which stores a <name, matrix>.
the possible way to do it would be to use http://www.mathworks.com/help/matlab/map-containers.html