User:DukeEgr93/TechSupport

Questions and Answers

How can I dynamically load files?

You will want to use MATLAB:Flexible Programming for this. Given that the file names have strings in them, you will also likely want to use a cell array to store the color names. Here's some code to help you figure out what to do:

• Cell arrays are surrounded by curly brackets; you can put different-size strings in the elements of a cell array; for instance, you could have:

Colors = {'Red', 'White', 'Blue'}

To access the string, you would put an index in curly brackets after the name of the variable; for example

Colors{2}

would return the string White. To load a file with a color name in it, you could use flexible programming to create a string with the appropriate load command and then use eval to execute it. For example, if you needed to load data from a file called MyVals_White_3.mat where the 3 comes from some variable Set then what you really want is the command

load MyVals_White_3

To create that with sprintf, you could use:

sprintf('load MyVals_%s_%d', Colors{2}, Set)

To make this printed command run, put it in an eval function:

eval(sprintf('load MyVals_%s_%d', Colors{2}, Set))

How can I keep track of the matrices I load

Your data files each have a matrix called Voltages so if you run the command

load LED_01_BLUE

you will have a matrix called Voltages available to you. The problem is, if you then run

load LED_01_GREEN

the Voltages matrix from that file will overwrite the original. You will therefore need to figure out how to keep track of the correct files. There are several options:

• Load the file, then copy the data to a new file:

load LED_01_Blue
VoltagesBlue = Voltages

• Load the file into a struct:

BlueFile = load('LED_01_Blue')

At this point, there is a struct called BlueFile and within it, there is a variable called Voltages - since it is a struct, to access it, you would need to write something like

BlueFile.Voltages

Plotting the second column of data versus the first would therefore look like:

plot(BlueFile.Voltages(:,1), BlueFile.Voltages(:,2))

Really Fancy

You could get really fancy with structs by having a variable (in this example I call it AllVals) that has an index based on which set you are loading and what color you are using and then stores the voltages in a field called V. For instance:

load LED_01_Blue
AllVals(1,1).V = Voltages
load LED_02_Blue
AllVals(2,1).V = Voltages
load LED_01_Green
AllVals(1,2).V = Voltages
load LED_02_Green
AllVals(2,2).V = Voltages

will create a variable called AllVals that has four items in it. The first index would be which set and the second would relate to a color. If you wanted to plot set 2's Blue LED resistor voltage as a function of the total, that command would become:

plot(AllVals(2,1).V(:,1), AllVals(2,1).V(:,2))

How can I make button presses switch tabs?

Create a callback for when the button is pushed and then add code to it that looks like:

app.TabGroup.SelectedGroup = app.Tab2

where app.Tab2 will be the name of the tab you want to make active.

How can I put information into a data table?

Probably the easiest way to do this is to put strings in -- even if some of the information is numerical -- in order to have complete control over the formatting. Imagine you have a three-column data table and in each row of the table you want to have a word, a number formatted using scientific notation with three decimal digits (i.e. four significant figures), and a floating point number formatted with two decimal digits (i.e. three significant figures). You might have code that resembles:

app.UITable.ColumnName = {'Words', 'Scientific', 'Floating'}
app.UITable.ColumnFormat = {'char', 'char', 'char'}
Words = {'Lets', 'Go', 'Duke'}
Nums1 = 1000*rand(3,1);
Nums2 = randi([0 1000], 1, 3)/100
for k=1:3
    app.UITable.Data{k,1} = Words{k};
    app.UITable.Data{k,2} = sprintf('%0.3e', Nums1(k));
    app.UITable.Data{k,3} = sprintf('%0.2f', Nums2(k));
end