1. 1. Definition 2. Creating Cell Arrays 3. Augmenting Cell Arrays 4. Referencing Cell Arrays 5. Special case 6. Spreadsheets 1

2.  Recall the workspace frame in MATLAB. Currently, 4 types of data have been seen. They are called:  This chapter teaches how to operate more specifically with the cell array 2

3.  Data type that holds information indexed in containers called cells  A cell can hold any data type- string, integer, float, another cell array… 3 Simply It is an ARRAY of CELLS

4.  Create a cell array by using the {} brackets  Separate each element in the array with a comma 4 Curly braces – not parentheses, not brackets!

5.  Plot them using cellplot()! 5 FYI: It is just a representation. J is in the first box, o in the second, e in the third.

6.  Adding on a new cell to the array  Example, add on the string 'def'. 6

7.  { } are not used to augment. They are strictly used to create new cell-arrays from scratch.  The curly braces indicate ‘def’ is added OUTSIDE of the cell-array C – i.e. C is a completely new cell-array! 7 NOT what we wanted...

8.  Augment the same as with normal arrays: use brackets 8

9.  Can a 2D cell-array exist? Of course.  Still use the ; operator to add a new row. 9

10.  There are 2 ways to reference a cell array, depending on the task: 1. Get the entire container as a whole. (Do not open the doors to see the content)  to move the container  to extract/copy/replace the container  to delete the container 2. Get the content inside the container. (Open the doors, and use the content)  To change its content  To display/print its content 10

11. 1. Get the entire container as a whole. (Do not open the doors to see the content) 2. Get the content inside the container. (Open the doors, and use the content) 11 Parentheses () Curly Braces {}

12.  Assume C starts with: %option1: refer to & delete the 2 nd container 12

13.  Assume C starts with: %option1: refer to & delete the 2 nd container %option2: refer to & delete the content of the 2 nd container 13

14.  This is particularly important if you wish to use the values mathematically (equations, … )  For example:  Using the variable X mathematically creates issues... 14 The content (numerical value 2) is still inside the container, as indicated per the brackets.

15.  To use this variable X mathematically creates an error  After all, this is what MATLAB tries to execute: result = 2* + 5 15 ?

16.  Recall to use curly braces to access the CONTENT. 16 Use curly braces {}. Notice the lack of [] around the result.

17.  To conclude, also use curly braces to replace elements. 17 Initial data-base (name, age, weight) Fix the name

18.  What if there is an array within a cell? 18 1) max? 2) last score?

19.  What if there is an array within a cell?  "Max of the content of container 2". Use { }. 19 1) max?

20.  The following requires patient imagination skills, but it works and makes sense! 20 Simply: "Reference to the 3 rd element in the CONTENT of the 2 nd container" Simply: "Reference to the last element in the CONTENT of the 2 nd container"

21.  Most would prefer storing the content in a intermediate variable, then referencing that variable. 21

22.  Syntax: [NUM,TXT,RAW]=xlsread(FILE)  You can select which sheet you want to read into Matlab(the first sheet is the default)  Reads data from the first worksheet in the Microsoft Excel spreadsheet file named FILE  NUM is a matrix with just the numerical values found in the table.  TXT is a cell array with the textual information found in the table.  RAW is a cell array with numbers and text  Syntax: xlswrite(FILE,ARRAY) 22 Example!

23.  Syntax: RESULT = dlmread(FILENAME)  The delimiter is inferred from the formatting of the file.  All data in the input file must be numeric.  Fills empty delimited fields with zero  dlmread( ) cannot handle text data file properly 23

24.  Numbers have different precisions and formats delimiters (spaces, tabs, ;) separate columns Space delimiterComma delimiter 24 1 3.00 32 2 3.20 36 3 2.40 35 4 1.60 37 5 2.80 39 1, 3.00, 32 2, 3.20, 36 3, 2.40, 35 4, 1.60, 37 5, 2.80, 39

25.  Syntax: RESULT= importdata(FILENAME)  importdata( ) will separate the text columns and the numeric columns into separate fields in a structure  The contents of the structure can be copied into numeric variables for analysis 25

26.  Cells arrays are ‘cargo-ships’  Rectangular arrays allowing storage of different data-types into 1 variable.  Cell-arrays use all types of braces: Creating/hard-coding: Braces { } Referencing to content:Braces { } Augmenting:Brackets [ ] Referencing to container: Parentheses ()  For more useful information about Cell Arrays, please visit: http://www.mathworks.com/help/techdoc/matlab_pro g/br04bw6-98.html http://www.mathworks.com/help/techdoc/matlab_pro g/br04bw6-98.html 26 Most likely to be used often!

27. 1. Dialog Boxes: Overview 2. Inputdlg() 3. listdlg() 4. msgbox() 5. questdlg() 6. menu() 27

28.  Dialog boxes are “popup windows” that allows another means to communicate with the user.  There are dialog boxes to collect input: inputdlg(), listdlg(), menu(), questdlg()  And there are dialog boxes to produce output: msgbox(), warndlg() 28 99% of the time, the command deals with cell arrays, either as arguments, as return-values, or both!

29.  Timing wise:  Modal (“waiting”) – they prevent the program from continuing until the box is closed  Non-modal (“non-waiting”) – the program continues execution while the box remains open  Examples:  Input boxes are generally modal – the program waits for input before continuing. This is not changeable.  Output boxes default to non-modal (“non-waiting”) but can be made modal. 29

30.  inputdlg() – much like the input() function, except…  It is presented in a GUI form  There can be multiple prompts and multiple values provided by the user.  ALL user-provided information is returned as strings in a cell array! That’s why learning about cell-arrays is important! 30

31.  Prompt the user for the coefficients to the quadratic equation, then solve for the roots.  Requirements: Use a Graphical User Interface (GUI) to prompt the values, specifically inputdlg() 31 …

32.  Arguments  A cell array of strings: This is the set of prompts for the user. For example: prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}  Return Values  one (1) cell-array of strings: What the user provided in the boxes  Full Example prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}; coeffs = inputdlg(prompts); 32 Cell-array, indicated by the curly braces.

33. 33  When collecting numbers, use str2double() to convert the cell-array (cargo-ship) into a numerical vector: coeffs = str2double(coeffs);

34. 34 clear clc prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}; flag=1; % No invalid inputs, or imaginary roots while (flag) % Collect the coeff’s from the user coeffs = inputdlg(prompts); coeffs = str2double(coeffs); a = coeffs(1); b = coeffs(2); c = coeffs(3); if (a==0 || (b^2 - 4*a*c) < 0) % No invalid inputs, or imaginary roots fprintf('invalid values\n'); else flag=0; end %calculate roots roots(1) = (-b + sqrt(b*b-4*a*c))/(2*a); roots(2) = (-b - sqrt(b*b-4*a*c))/(2*a)

35. 35 clear clc prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}; flag=1; % No invalid inputs, or imaginary roots while (flag) % Collect the coeff’s from the user coeffs = inputdlg(prompts); coeffs = str2double(coeffs); a = coeffs(1); b = coeffs(2); c = coeffs(3); if (a==0 || (b*b - 4*a*c) < 0) % No invalid inputs, or imaginary roots fprintf('invalid values\n'); else flag=0; end %calculate roots roots(1) = (-b + sqrt(b*b-4*a*c))/(2*a); roots(2) = (-b - sqrt(b*b-4*a*c))/(2*a) Extract the values from the vector: Must this be done, or should it be done for convenience?

36. 36 clear clc prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}; flag=1; % No invalid inputs, or imaginary roots while (flag) % Collect the coeff’s from the user coeffs = inputdlg(prompts); coeffs = str2double(coeffs); if (coeffs(1)==0 || (coeffs(2)^2 - 4*coeffs(1)*coeffs(3)) < 0) % No invalid inputs, or imaginary roots fprintf('invalid values\n'); else flag=0; end %calculate roots roots(1) =(-coeffs(2) + sqrt(coeffs(2)^2- 4*coeffs(1)*coeffs(3)))/(2*coeffs(1)); roots(2) =(-coeffs(2) - sqrt(coeffs(2)^2- 4*coeffs(1)*coeffs(3)))/(2*coeffs(1)) Really.. 

37. 37 clear clc prompts={'Coeff "a":', 'Coeff "b":', 'Coeff "c":'}; flag=1; % No invalid inputs, or imaginary roots while (flag) % Collect the coeff’s from the user coeffs = inputdlg(prompts); coeffs = str2double(coeffs); a = coeffs(1); b = coeffs(2); c = coeffs(3); if (a==0 || (b*b - 4*a*c) < 0) % No invalid inputs, or imaginary roots fprintf('invalid values\n'); else flag=0; end %calculate roots roots(1) = (-b + sqrt(b*b-4*a*c))/(2*a); roots(2) = (-b - sqrt(b*b-4*a*c))/(2*a) Since the prompts do not change each time it loops, avoid having this line within the loop. Time & effort consuming for Matlab.

38. 38  Syntax: [SELECTION,OK]=listdlg('ListString',S)  Creates a modal list-selection dialog box  SELECTION is a vector of indices of the selected strings ▪ length 1 in the single selection mode ▪ This will be [] when OK is 0  OK=1 if you push the OK button,  OK=0 if you push the Cancel button or close the figure.

39. Inputs are in parameter/value pairs (i.e. they go 2 by 2): Parameter goes 1st, value of the parameter goes 2nd. The actual string: 39

40. myList is a CELL ARRAY of string: { } Why cell arrays? The length of each selection varies widely, and an regular-array would not be rectangular. 40

41. 41 The Select All button is gone.

42.  Syntax: msgbox(Message, Title, Icon)  Message is a string vector, string matrix or cell array.  Could be modal or non-modal  Title: specifies the title of the message box  Icon: specifies which Icon to display in the message box. ▪ Icon is 'none', 'error', 'help', 'warn', or 'custom'. The default is 'none'. 42

43.  Syntax: ButtonName = questdlg(Question, Title,Btn1,Btn2,Btn3,DEFAULT)  creates a modal dialog box that automatically wraps the cell array or string  Up to 3 custom button names may be specified  default = String that is the default button  button = string on the button that was clicked  If the dialog is closed without a valid selection, the return value is empty. 43

44.  button = string on the button that was clicked 44

45.  Syntax: button = menu('qstring','bt1','bt2',……,'btn')  qstring = question to ask user  bt1 = String to show on Button #1  bt2 = String to show on Button #2  Can have as many options as desired.  There is no default answer.  Return value: Button number clicked (not the string) 45

46. 46

47. 47

48.  Dialog boxes are user friendly but time taking  We saw:  inputdlg()  listdlg()  msgbox()  questdlg()  menu()  NEVER learn the syntax by heart. Practice it enough, then use the doc to remind yourself quickly! 48

49.  If you want to do more than fundamental dialog boxes, study the MATLAB help documentation.  http://www.mathworks.com/help/techdoc/ref/f 16-40727.html#f16-8026 49 F1 = Help