A table consists of several row variables and several column variables. Each variable in a table can have a different data type and size, but there is one restriction: each variable must have the same number of rows.
Creating Tables
Use the table function to create a table based on existing variables, or use the readtable function to create a table based on a file.
Use the table function to create a table based on existing variables, or use the readtable function to create a table based on a file.
1. Creating a Table from Workspace Variables
[Example 2-68]
First create workspace variables with the same number of rows.
ID = {'1';'2';'3';'4'};
Name = {'张三';'李四';'杨二';'王五'};
Age = [18;19;17;20];
Height = [162;169;164;167];
Weight = [116;103;131;133];
Then use the table function to create the table. Use the 'RowNames' name-value pair below to specify the row names as the values of ID.
T=table(Name,Age,Height,Weight, 'RowNames',ID)
T =
Name Age Height Weight
____ ___ ______ ______
1 '张三' 18 162 116
2 '李四' 19 169 103
3 '杨二' 17 164 131
4 '王五' 20 167 1332. Creating Table Content and Specifying Variable Names
[Example 2-69]
First create the content of the table, then use the 'VariableNames' name-value pair to specify the variable names.
>> T = table(categorical({'张三';'李四';'杨二';'王五'}),{'M';'F';'M';'F'},[18;19;17;25],...
[162;169;164;167],logical([0;0;0;1]),...
'VariableNames',{'Name' 'Gender' 'Age' 'Height' 'Married'})
>> T =
Name Gender Age Height Married
____ ______ ___ ______ _______
张三 'M' 18 162 false
李四 'F' 19 169 false
杨二 'M' 17 164 false
王五 'F' 25 167 true3. Creating a Table Using Object Reference
[Example 2-70]
This method first creates an empty table object, then specifies variable names and values using object reference.
Enter in the Command Window:
ID = {'1';'2';'3';'4'};
Name = {'张三';'李四';'杨二';'王五'};
Age = [18;19;17;20];
Height = [162;169;164;167];
Weight = [116;103;131;133];
T=table;
T.ID=ID;
T.Name=Name;
T.Age=Age;
T.Height=Height;
T.Weight=Weight
T =
ID Name Age Height Weight
___ ____ ___ ______ ______
'1' '张三' 18 162 116
'2' '李四' 19 169 103
'3' '杨二' 17 164 131
'4' '王五' 20 167 1334. Creating a Table Using the readtable Function
[Example 2-71]
First use Notepad to create a text file containing table data, as shown in Figure 2-4. Save the file in the examples\matlab subdirectory of the MATLAB installation directory, named demo.dat.
Figure 2-4: Text File Containing Table Data
Enter in the Command Window:
filename = fullfile(matlabroot,'examples','matlab','demo.dat');
T=readtable(filename)
Generate table:
T =
ID Name Age Height Weight
__ ____ ___ ______ ______
1 '张三' 18 162 116
2 '李四' 19 169 103
3 '杨二' 17 164 131
4 '王五' 20 167 133Use the writetable function to write the table to a file.
Table Operations and Associations
In MATLAB, you can conveniently perform intersection, difference, exclusive OR (XOR), and union operations on tables.
[Example 2-72]
Create the following two tables.
A = table(categorical({'1';'2';'3';'4'}),{'张三';'李四';'杨二';'王五'},{'M';'F';'M';'F'},[18;19;17;25],...
[162;169;164;167],logical([0;0;0;1]),...
'VariableNames',{'ID' 'Name' 'Gender' 'Age' 'Height' 'Married'})
A =
ID Name Gender Age Height Married
__ ____ ______ ___ ______ _______
1 '张三' 'M' 18 162 false
2 '李四' 'F' 19 169 false
3 '杨二' 'M' 17 164 false
4 '王五' 'F' 25 167 true
B = table(categorical({'3';'6';'8';'10'}),{'杨二';'赵旭';'东方允';'夏东'},{'M';'M';'M';'M'},[17;20;18;23],...
[164;159;162;165],logical([0;0;0;1]),...
'VariableNames',{'ID' 'Name' 'Gender' 'Age' 'Height' 'Married'})
B =
ID Name Gender Age Height Married
__ _____ ______ ___ ______ _______
3 '杨二' 'M' 17 164 false
6 '赵旭' 'M' 20 159 false
8 '东方允' 'M' 18 162 false
10 '夏东' 'M' 23 165 true1. Finding the Intersection of Two Tables
Use the intersect function to find the intersection of two tables below.
C=intersect(A,B)
C =
ID Name Gender Age Height Married
__ ____ ______ ___ ______ _______
3 '杨二' 'M' 17 164 false2. Finding the Difference of Two Tables
Use the setdiff function to find the difference of two tables below. The difference of tables A and B is the result of removing the intersection of A and B from A.
C=setdiff(A,B)
C =
ID Name Gender Age Height Married
__ ____ ______ ___ ______ _______
1 '张三' 'M' 18 162 false
2 '李四' 'F' 19 169 false
4 '王五' 'F' 25 167 true3. Finding the Union of Two Tables
Use the union function to find the union of two tables below.
C=union(A,B)
C =
ID Name Gender Age Height Married
__ _____ ______ ___ ______ _______
1 '张三' 'M' 18 162 false
2 '李四' 'F' 19 169 false
3 '杨二' 'M' 17 164 false
4 '王五' 'F' 25 167 true
10 '夏东' 'M' 23 165 true
6 '赵旭' 'M' 20 159 false
8 '东方允' 'M' 18 162 false4. Finding the Exclusive OR (XOR) of Two Tables
Use the setxor function to find the exclusive OR of two tables below. The result of the XOR operation on two tables is the data not in the intersection of the two tables, excluding duplicates.
C=setxor(A,B)
C =
ID Name Gender Age Height Married
__ _____ ______ ___ ______ _______
1 '张三' 'M' 18 162 false
2 '李四' 'F' 19 169 false
4 '王五' 'F' 25 167 true
10 '夏东' 'M' 23 165 true
6 '赵旭' 'M' 20 159 false
8 '东方允' 'M' 18 162 falseTable Conversion
Use the array2table and table2array functions to convert between tables and arrays.
[Example 2-73]
For array A:
A=[1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9Use the array2table function to convert array A to a table.
T=array2table(A)
T =
A1 A2 A3
__ __ __
1 2 3
4 5 6
7 8 9For table T:
T = table([1;2;3],[2 5; 6 9; 6 10], 'VariableNames',{'One' 'Two'})
T =
One Two
___ _______
1 2 5
2 6 9
3 6 10Use the table2array function to convert table T to an array.
A=table2array(T)
A =
1 2 5
2 6 9
3 6 10Functions for converting between tables, timetables, structures, and cell arrays are shown in Table 2-11.
Table 2-11: Functions for Converting Between Tables, Timetables, Structures, and Cell Arrays
| Function | Description |
|---|---|
| cell2table | Convert cell array to table. |
| struct2table | Convert structure to table. |
| table2cell | Convert table to cell array. |
| table2struct | Convert table to structure. |
| timetable2table | Convert timetable to table. |
| table2timetable | Convert table to timetable. |
A=table2array(T)
A =
1 2 5
2 6 9
3 6 10Functions for converting between tables, timetables, structures, and cell arrays are shown in Table 2-11.