From fa32f4a3fdebd698b0ef5f176742aed1386e6802 Mon Sep 17 00:00:00 2001
From: Enrico Lumetti <enrico.lumetti@gmail.com>
Date: Mon, 15 Mar 2021 17:41:55 +0100
Subject: [PATCH] First commit

---
 BasicClass.m              | 25 +++++++++++++++
 basic_casting.m           |  9 ++++++
 cell_array.m              | 31 ++++++++++++++++++
 conditional_statements.m  | 51 +++++++++++++++++++++++++++++
 function_handles.m        |  7 ++++
 logic_datatypes.m         | 17 ++++++++++
 map_container.m           | 45 ++++++++++++++++++++++++++
 matrix_intro.m            | 57 +++++++++++++++++++++++++++++++++
 matrix_manipulation.m     | 67 +++++++++++++++++++++++++++++++++++++++
 matrix_reshape.m          |  8 +++++
 meta_functions.m          | 29 +++++++++++++++++
 multidimensional_arrays.m |  0
 objects.m                 | 32 +++++++++++++++++++
 scalar_types.m            | 16 ++++++++++
 string_operations.m       | 58 +++++++++++++++++++++++++++++++++
 struct_arrays.m           | 29 +++++++++++++++++
 tables.m                  |  0
 try_catch.m               |  0
 tseries.m                 |  0
 19 files changed, 481 insertions(+)
 create mode 100644 BasicClass.m
 create mode 100644 basic_casting.m
 create mode 100644 cell_array.m
 create mode 100644 conditional_statements.m
 create mode 100644 function_handles.m
 create mode 100644 logic_datatypes.m
 create mode 100644 map_container.m
 create mode 100644 matrix_intro.m
 create mode 100644 matrix_manipulation.m
 create mode 100644 matrix_reshape.m
 create mode 100644 meta_functions.m
 create mode 100644 multidimensional_arrays.m
 create mode 100644 objects.m
 create mode 100644 scalar_types.m
 create mode 100644 string_operations.m
 create mode 100644 struct_arrays.m
 create mode 100644 tables.m
 create mode 100644 try_catch.m
 create mode 100644 tseries.m

diff --git a/BasicClass.m b/BasicClass.m
new file mode 100644
index 0000000..fed3e1c
--- /dev/null
+++ b/BasicClass.m
@@ -0,0 +1,25 @@
+classdef BasicClass
+   properties
+      Value {mustBeNumeric}
+   end
+   methods
+      % contstructor
+      function obj = BasicClass(value)
+          % obj is by default an instance of BasicClass, no need to assign
+          if nargin == 1
+              obj.Value = value;
+          end
+      end
+      function r = roundOff(obj)
+         r = round([obj.Value],2);
+      end
+      function r = multiplyBy(obj,n)
+         r = [obj.Value] * n;
+      end
+      % operator overloading
+      function r = plus(o1, o2)
+          % [x.Value] used to support object arrays by default
+          r.Value = [o1.Value] + [o2.Value];
+      end
+   end
+end
\ No newline at end of file
diff --git a/basic_casting.m b/basic_casting.m
new file mode 100644
index 0000000..dc0a7f7
--- /dev/null
+++ b/basic_casting.m
@@ -0,0 +1,9 @@
+clear
+
+assert(str2double('3') == double(3));
+assert(str2double('3.4') == double(3.4));
+assert(all(str2num('1 2 3') == [1 2 3 ]));
+assert(isnan(str2double('1 2 3')));
+assert(all(int2str(1.2) == int2str(1)));
+assert(all(num2str(1.2) == '1.2'));
+assert(all(mat2str([1 2 3]) == '[1 2 3]'));
\ No newline at end of file
diff --git a/cell_array.m b/cell_array.m
new file mode 100644
index 0000000..eafae66
--- /dev/null
+++ b/cell_array.m
@@ -0,0 +1,31 @@
+clear
+
+% cell arrays are like n-dimensional arrays, but have hetergeneous
+% data-types inside
+
+a = {'p'};
+v = {1 'a'};
+D = {1 2; 't' [1 2]};
+
+% like vectors, scalars, and matrices, cell arrays are two-dimensional
+% by default
+assert(ndims(a) == 2);
+assert(ndims(v) == 2);
+assert(ndims(D) == 2);
+
+% indexing a cell array follows the same rules, and returns another cell
+% array (like indexing a matrix returns a matrix, remember that scalar
+% are 1x1 matrices
+assert(all(size(D(2, 2)) == [1 1]));
+
+% to unbox the cell values, index with {} instead of ()
+% this will return a matrix instead of a cell
+assert(D{2,1} == 't');
+assert(all(D{2, 2} == [1 2]));
+
+% equality check:
+cs = {1+3 2};
+assert(isequal(cs, {4 2}));
+
+% convert cell array to standard array
+assert(isequal(cell2mat(cs), [4 2]));
\ No newline at end of file
diff --git a/conditional_statements.m b/conditional_statements.m
new file mode 100644
index 0000000..896bacb
--- /dev/null
+++ b/conditional_statements.m
@@ -0,0 +1,51 @@
+% if statement
+a = randi(100);
+
+if a > 66
+    disp('a is greater than 66')
+elseif (a > 33) && (a <= 66)
+    disp('a is between (33, 66]')
+else
+    disp('a is between 1 and 33')
+end
+
+% switch/case
+choices = ['A', 'B', 'C', 'D'];
+idx = mod(a, numel(choices)) + 1;
+
+switch choices(idx)
+    case 'A'
+        disp('A choosen')
+    case 'B'
+        disp('B choosen')
+    case 'C'
+        disp('C choosen')
+    otherwise
+        disp('Invalid choice')
+end
+
+% for statement
+
+% this is intuitive
+for i = 1:3:10
+    disp("i = " + string(i));
+end
+
+% this as well
+v = [1 2 3];
+for el = v
+    disp("el = " + string(el));
+end
+
+% when you iterate on a matrix, you iterate by columns
+A = [1 2; 3 4; 5 6];
+for column = A
+    disp(column);
+end
+
+% to iterate by rows
+for row = A.'
+    disp(row);
+end
+
+% while loop: too easy
\ No newline at end of file
diff --git a/function_handles.m b/function_handles.m
new file mode 100644
index 0000000..7f4c8c7
--- /dev/null
+++ b/function_handles.m
@@ -0,0 +1,7 @@
+numbers = [1 2 3 4 5];
+
+% @name_of_existing_function
+arrayfun(@sqrt, numbers)
+
+% anonymous function
+arrayfun(@(n) n*n, numbers)
\ No newline at end of file
diff --git a/logic_datatypes.m b/logic_datatypes.m
new file mode 100644
index 0000000..389d8c9
--- /dev/null
+++ b/logic_datatypes.m
@@ -0,0 +1,17 @@
+clear
+
+a = true;
+array_of_logicals = [1 2 3] == [2 2 4];
+array_of_logicals ~= [false true false]; %[false true false]
+assert(all(array_of_logicals == [false true false]));
+
+true(1, 3); % = [true true true]
+
+islogical(true); % true
+islogical([true false]); % true
+
+% logical not
+assert(~true == false);
+
+% checking equality of complex types
+res = isequal(eye(3), [1 0 0; 0 1 0; 0 0 1]);
\ No newline at end of file
diff --git a/map_container.m b/map_container.m
new file mode 100644
index 0000000..eac8543
--- /dev/null
+++ b/map_container.m
@@ -0,0 +1,45 @@
+% a map is an instance of a Map class
+
+% creates an empty map
+emptyMap = containers.Map;
+
+% .Count: total number of key/value pairs
+assert(emptyMap.Count == 0);
+% .KeyType: class of the key value
+% by default set to 'char'
+assert(isequal(emptyMap.KeyType, 'char'));
+
+% .ValueType: class of the values
+% by default set to 'any'
+assert(isequal(emptyMap.ValueType, 'any'));
+
+% create initalized map
+% note: keys can only be
+% - integers scalars
+% - 1xN char arrays
+% - double or single scalars
+pairs = containers.Map({'Name', 'Msg'}, {"Enrico", "Hello"});
+assert(pairs.Count == 2);
+assert(isequal(pairs.KeyType, 'char'));
+assert(isequal(pairs.ValueType, 'any')); % this didn't change
+
+% size(map, 1) is equivalent to .Count
+assert(pairs.Count == size(pairs, 1));
+
+% size(map, 2) = size(map, 3) = ... = 1 (map is sort of nx1)
+assert(size(pairs, 23) == 1);
+
+% size(map) returns [map.Count 1]
+assert(isequal( size(pairs), [pairs.Count 1] ));
+
+% keys() returns the sorted keys as a cell array
+assert(isequal( keys(pairs) , sort({'Name', 'Msg'})));
+
+% values() returns the map values, sorted as the corresponding keys
+assert(isequal( values(pairs), {"Hello", "Enrico"} ));
+
+% index map by key
+assert(isequal( pairs('Msg'), "Hello" ));
+
+% change a value
+pairs('Msg') = "World";
\ No newline at end of file
diff --git a/matrix_intro.m b/matrix_intro.m
new file mode 100644
index 0000000..4661df8
--- /dev/null
+++ b/matrix_intro.m
@@ -0,0 +1,57 @@
+clear
+
+% scalar and vectors are matrices
+a =  13;
+assert(a(1,1) == 13);
+    
+v = [1 2 3]; % vectors are row vector by default
+t = [4,5,6]; % can also use comma to separate values
+assert(v(1,2) == 2);
+assert(v(2) == 2);
+t_col = t.'; % column vector given by transpose
+assert(t_col(3, 1) == 6);
+
+% complex transpose (adjoint matrix)
+s = [1+1i 3-1i];
+assert(all(s' == [1-1i 3+1i].'));
+
+% size() finds the matrix dimensions of something
+assert(all(size(a) == [1 1]));
+assert(all(size(v) == [1 3]));
+assert(all(size(v') == [3 1]));
+
+% length() returns the largest dimension given by size()
+assert(length(a) == 1);
+assert(length(v) == 3);
+assert(length(v.') == 3);
+
+% isempty() is equivalent to length(X) == 0
+assert(isempty(a) == false);
+assert(isempty([]) == true);
+
+% ndims() is equivalent so length(size(v))
+% this proves that scalars and vectors are matrices
+assert(ndims(a) == 2);
+assert(ndims(v) == 2);
+assert(ndims(v.') == 2);
+
+% create a 3x3 matrix: rows separated by ;
+M = [1 2 3; 4 5 6; 0 -1 -2];
+
+assert(M(2, 3) == 6);
+all(M' == [1 4 0; 2 5 -1; 3 6 -2]); % all operates on the first dimensions
+                                    % returns [1 1 1];
+% check all elements (i.e. all dimensions) by doing
+assert(all(M.' == [1 4 0; 2 5 -1; 3 6 -2], 'all'));
+% can be done better by doing
+assert(isequal(M.', [1 4 0; 2 5 -1; 3 6 -2]));
+
+% note: length on a matrix is not the number of elements
+%       but the size of the max dimension
+assert(length(M) == 3);
+
+% numel() is equivalent to multiplying the entries given by size()
+% returns the number of scalar elements
+assert(numel(a) == 1);
+assert(numel(v) == 3);
+assert(numel(M) == 9);
diff --git a/matrix_manipulation.m b/matrix_manipulation.m
new file mode 100644
index 0000000..e098784
--- /dev/null
+++ b/matrix_manipulation.m
@@ -0,0 +1,67 @@
+clear
+
+a1 = [1 2 3];
+a2 = [4, 9, 10];
+
+% create 3x2 matrix by joining columns
+% two equivalent ways:
+A = [a1.', a2.'];
+A = horzcat(a1.', a2.');
+A = cat(2, a1.', a2.'); % 2 selects the dimension that varies
+                        % which is the dimension along which it concatenates
+                        % 2 == column
+
+% create a 2x3 matrix by joining rows
+B = [a1; a2];
+B = vertcat(a1, a2);
+B = cat(1, a1, a2); % columns stay the same
+
+% note:
+assert(all(horzcat(a1, a2) == [1 2 3 4 9 10])); % not as above!
+
+% also, comparision of row and column vectors gives non obvious result:
+assert(all(a1 == a2.' == false(3), 'all'));
+
+% ranges
+assert(all(1:3 == [1 2 3]));
+assert(all((1:3).' == [1 2 3]'));
+
+% non integer ranges
+% default step is 1
+assert(all(1.5:3.5 == [1.5 2.5 3.5]));
+% different step: note that 10 is included
+assert(all(1 : 3 : 10 == [1 4 7 10]));
+assert(all(1.3 : 2.2 : 5 == [1.3 3.5]));
+
+C = [A [2 9 8].'];
+
+% select one element
+assert(C(2, 1) == 2);
+% select element 1 and 3 on the second row
+assert(all(C(2, [1 3]) == [2 9]));
+% select element 1 and 3 on the first column
+% note that the resulting entries are in a column vector
+assert(all(C([1 3], 1) == [1 3].'));
+
+% select the whole third row: progressively smarter
+assert(all(C(3, [1, 2, 3]) == [3 10 8]));
+assert(all(C(3, 1:3) == [3 10 8]));
+assert(all(C(3, :) == [3 10 8]));
+
+assert(all(C(:, :) == C, 'all'));
+
+% select the whole second column
+assert(all(C(:, 2) == [4 9 10].'));
+
+% select the first and the third column, joining them
+assert(all(C(:, [1 3]) == [1 2 3; 2 9 8].', 'all'));
+
+
+% todo: linear indexing and logical indexing
+%       sub2ind ind2sub
+assert(all(A(:) == [1 2 3 4 9 10].'));
+
+% remove elements from an array
+D = [1, 3, 6, 2, 3, 1];
+D(D == 3) = []; % remove all threes
+assert(isequal(D, [1, 6, 2, 1]));
\ No newline at end of file
diff --git a/matrix_reshape.m b/matrix_reshape.m
new file mode 100644
index 0000000..570601d
--- /dev/null
+++ b/matrix_reshape.m
@@ -0,0 +1,8 @@
+clear
+
+v = 1:12;
+
+% reshape v as 4x3 matrix
+M = reshape(v, [4,3]);
+% note: M(:) is a column vector
+assert(all(M(:) == v.'));
\ No newline at end of file
diff --git a/meta_functions.m b/meta_functions.m
new file mode 100644
index 0000000..912e970
--- /dev/null
+++ b/meta_functions.m
@@ -0,0 +1,29 @@
+clear
+
+A = [1 2 3];
+b = true;
+
+% print the list of variables in the workspace
+who
+% if saved to a variable, saves the variables as a nx1 cell
+vars = who;
+
+% prints all variables along with class, size, byes, attributes
+whos
+
+% prints info for a single var
+whos A
+% identify the type of a variable
+class(A)
+class(b)
+c = int32(3); % class doesn't work with literals :(
+class(c)
+
+% test for data type
+isinteger(c)
+isnumeric(A), isnumeric(c)
+ismatrix(c)
+isa(A, 'numeric')
+
+% find the file where a user or built-in function is defined
+which eye;
\ No newline at end of file
diff --git a/multidimensional_arrays.m b/multidimensional_arrays.m
new file mode 100644
index 0000000..e69de29
diff --git a/objects.m b/objects.m
new file mode 100644
index 0000000..ffee69c
--- /dev/null
+++ b/objects.m
@@ -0,0 +1,32 @@
+% instantiate an object of type BasicClass (see BasicClass.m)
+obj = BasicClass;
+
+assert(isempty(obj.Value));
+
+obj.Value = 3;
+obj.Value = [3 4.5];
+
+% methods can be called in two ways
+roundOff(obj);
+% or dot notation
+obj.roundOff();
+
+% use the constructor
+v = BasicClass(42);
+assert(v.Value == 42);
+
+% object arrays are presto supported
+objs(1) = BasicClass(44);
+objs(2) = BasicClass(33);
+
+% [objs.Value] expands to [objs(1).Value ...]
+assert(isequal( [objs.Value], [44 33] ));
+
+% you can also do this with a cell array
+assert(isequal( {objs.Value}, {44, 33} ));
+
+% operator overloading
+obj + objs(1);
+
+% also works for object arrays
+[objs] + [objs]
\ No newline at end of file
diff --git a/scalar_types.m b/scalar_types.m
new file mode 100644
index 0000000..5c28226
--- /dev/null
+++ b/scalar_types.m
@@ -0,0 +1,16 @@
+clear
+
+% by default everything is double floating precision
+a = 3;
+assert(isequal(class(a), 'double'));
+
+% specify a different scalar type
+b = int8(100);
+assert(isequal(class(b), 'int8'));
+
+% also unsigned
+c = uint16(291);
+assert(isequal(class(c), 'uint16'));
+
+% a matrix of int32
+int32_matrix = int32([1 2; 3 4]);
\ No newline at end of file
diff --git a/string_operations.m b/string_operations.m
new file mode 100644
index 0000000..f810f13
--- /dev/null
+++ b/string_operations.m
@@ -0,0 +1,58 @@
+clear
+
+% two types for representing text:
+% 'char' arrays and 'string' arrays
+
+char_scalar = 'a';
+char_array = 'abc';
+% 'abc' is the same as ['a' 'b' 'c']
+assert(all(char_array == ['a' 'b' 'c']));
+assert(all(size(char_array) == [1 3]));
+
+char_matrix = ['abc'; 'def'];
+assert(numel(char_matrix) == 6);
+
+% string arrays provide functions to deal with them
+% this two are not equivalent!
+string_scalar = "Hello World!"; % < 1x1 string array
+string_array = ["Hello", "World"]; % < 1x2 string array
+assert(all(string_scalar ~= string_array));
+
+% convert a char array to a string
+msg = string(char_array);
+assert(ischar(char_array));
+assert(isstring(msg));
+
+% convert a number to a char array (despite the name!!)
+one = int2str(1);
+pi = num2str(3.14);
+arr = num2str([1 3]);
+
+assert(all(one == '1'));
+assert(all(pi == '3.14'));
+assert(all(arr == '1  3'));
+
+% convert something to a string
+one_s = string(1);
+pi_s = string(3.14);
+arr_s = string([1 3]);
+cell_s = string({1 10}); % cannot do this with num2str
+
+assert(one_s == "1");
+assert(pi_s == "3.14");
+assert(all(arr_s == ["1", "3"]));
+assert(isequal(cell_s, ["1", "10"])); % note that the result is a string array
+
+% get a char array length
+assert(numel('abc') == 3); % obvious
+% get a string length: less obvious
+assert(numel("abc") == 1);
+assert(strlength("abc") == 3);
+
+% concatenate strings: lot of ways (char, strings, cell of strings... plus
+% dimensionality)
+
+% basic way:
+assert(isequal("Hello" + " World", "Hello World"));
+% more correct (deals with char arrays and cell arrays of strings)
+assert(isequal(append("Hello", ' ', "World"), "Hello World"));
\ No newline at end of file
diff --git a/struct_arrays.m b/struct_arrays.m
new file mode 100644
index 0000000..0520ea1
--- /dev/null
+++ b/struct_arrays.m
@@ -0,0 +1,29 @@
+clear
+
+% create a struct array
+patient(1).name = 'John Doe';
+patient(1).billing = 127.00;
+patient(1).test = [79, 75, 73; 180, 178, 177.5; 220, 210, 205];
+
+% add an entry to the struct array
+patient(2).name = 'Ann Lane';
+patient(2).billing = 28.50;
+patient(2).test = [68, 70, 68; 118, 118, 119; 172, 170, 169];
+
+% creates a new records 'age'; this will be created in all the other
+% entries; fields not specified here are set to []
+patient(3).name = 'New Name';
+patient(3).age = 21;
+
+% creates a new struct array with the same layout
+customer(1).name = 'Enrico';
+customer(1).billing = 30.0;
+customer(1).test = [];
+customer(1).age = 25;
+
+% concatenates patient and customer to create a new struct array
+v = [patient customer]; % or [patient, customer]
+
+% can also concatenate in a matrix layout: this create a 2x2 struct matrix
+M = [patient(1:2); [customer patient(3)]];
+assert(all(M(2, 1).name == 'Enrico'));
diff --git a/tables.m b/tables.m
new file mode 100644
index 0000000..e69de29
diff --git a/try_catch.m b/try_catch.m
new file mode 100644
index 0000000..e69de29
diff --git a/tseries.m b/tseries.m
new file mode 100644
index 0000000..e69de29