sortrows

Sort rows of matrix or table

Syntax

B = sortrows(A)

B = sortrows(A,column)

B = sortrows(A,___,direction)

B = sortrows(A,___,Name,Value)

[B,index] = sortrows(A,___)

tblB = sortrows(tblA)

tblB = sortrows(tblA,'RowNames')

tblB = sortrows(tblA,rowDimName)

tblB = sortrows(tblA,vars)

tblB = sortrows(tblA,___,direction)

tblB = sortrows(tblA,___,Name,Value)

[tblB,index] = sortrows(tblA,___)

Description

Array Data

B = sortrows(A) sorts the rows of an array based on the elements in the first column. By default, sortrows uses ascending sorted order. When the first column contains repeated elements, sortrows sorts according to the values in the next column and repeats this behavior for succeeding equal values.

B = sortrows(A,column) specifies the columns by which to sort the rows. For example, sortrows(A,[4 6]) first sorts the rows of A based on elements in the fourth column, then based on elements in the sixth column to break ties.

B = sortrows(A,___,direction) specifies the sorting direction for any of the previous syntaxes. For example, sortrows(A,'descend') uses descending sorting order.

B = sortrows(A,___,Name,Value) specifies additional parameters for sorting rows. For example, sortrows(A,'ComparisonMethod','abs') sorts the elements in A by magnitude.

[B,index] = sortrows(A,___) also returns an index vector that describes the rearrangement of rows such that B = A(index,:).

Table Data

tblB = sortrows(tblA) sorts the rows of a table or timetable.

• If tblA is a table, then sortrows sorts tblA in ascending order based on the values in the first variable. If elements in the first variable are repeated, then sortrows sorts by the elements in the second variable, and so on.

• If tblA is a timetable, then sortrows sorts the rows of tblA in ascending order based on its row times. However, the rows are sorted only with respect to the row times. If row times are repeated, then sortrows does not sort by the elements in the timetable variables.

tblB = sortrows(tblA,'RowNames') sorts a table based on its row names. Row names of a table label the rows along the first dimension of the table. If tblA does not have row names, that is, if tblA.Properties.RowNames is empty, then sortrows returns tblA.

This syntax is not supported when tblA is a timetable.

tblB = sortrows(tblA,rowDimName) sorts based on row labels along the first dimension.

• If tblA is a table, then row labels are row names.

• If tblA is a timetable, then row labels are row times.

tblB = sortrows(tblA,vars) sorts based on the specified table variables. For example, sortrows(tblA,{'Var1','Var2'}) first sorts the rows of tblA based on the elements in Var1, then by the elements in Var2.

• If tblA is a table and it has row names, then vars can include the row names.

• If tblA is a timetable, then vars can include the row times.

tblB = sortrows(tblA,___,direction) sorts the rows in tblA in specified direction for any of the previous table syntaxes.

tblB = sortrows(tblA,___,Name,Value) specifies additional parameters for sorting rows of a table or timetable. For example, sortrows(tblA,'Var1','MissingPlacement','first') sorts based on the elements in Var1, ordering missing elements such as NaN at the beginning of the table.

[tblB,index] = sortrows(tblA,___) also returns an index vector such that tblB = tblA(index,:).

Examples

Sort Rows of Matrix

Create a matrix and sort its rows in ascending order based on the elements in the first column. When the first column contains repeated elements, sortrows looks to the elements in the second column to break the tie. For repeated elements in the second column, sortrows looks to the third column, and so on.

rng default;
A = floor(rand([6 7])*100);
A(1:4,1) = 95;  A(5:6,1) = 76;  A(2:4,2) = 7;  A(3,3) = 48

A = 6×7

    95    27    95    79    67    70    69
    95     7    48    95    75     3    31
    95     7    48    65    74    27    95
    95     7    14     3    39     4     3
    76    15    42    84    65     9    43
    76    97    91    93    17    82    38

B = sortrows(A) 

B = 6×7

    76    15    42    84    65     9    43
    76    97    91    93    17    82    38
    95     7    14     3    39     4     3
    95     7    48    65    74    27    95
    95     7    48    95    75     3    31
    95    27    95    79    67    70    69

Sort the rows of A based on the values in the second column. When the specified column has repeated elements, the corresponding rows maintain their original order.

C = sortrows(A,2)

C = 6×7

    95     7    48    95    75     3    31
    95     7    48    65    74    27    95
    95     7    14     3    39     4     3
    76    15    42    84    65     9    43
    95    27    95    79    67    70    69
    76    97    91    93    17    82    38

Sort the rows of A based on the elements in the first column, and look to the seventh column to break any ties.

D = sortrows(A,[1 7])

D = 6×7

    76    97    91    93    17    82    38
    76    15    42    84    65     9    43
    95     7    14     3    39     4     3
    95     7    48    95    75     3    31
    95    27    95    79    67    70    69
    95     7    48    65    74    27    95

Sort the rows of A in descending order based on the elements in the fourth column, and display the output vector index to see how the rows were rearranged.

[E,index] = sortrows(A,4,'descend')

E = 6×7

    95     7    48    95    75     3    31
    76    97    91    93    17    82    38
    76    15    42    84    65     9    43
    95    27    95    79    67    70    69
    95     7    48    65    74    27    95
    95     7    14     3    39     4     3

index = 6×1

     2
     6
     5
     1
     3
     4

Complex Matrix

Create a matrix containing complex numbers, and sort the rows of the matrix in ascending order based on the elements in the first column. Since the magnitudes of A(1,1) and A(3,1) are equal, sortrows computes their angles to break the tie.

A = [1+2i 3+i i; 2+10i 6i 2+5i; 2+i 4 3+3i]

A = 3×3 complex

   1.0000 + 2.0000i   3.0000 + 1.0000i   0.0000 + 1.0000i
   2.0000 +10.0000i   0.0000 + 6.0000i   2.0000 + 5.0000i
   2.0000 + 1.0000i   4.0000 + 0.0000i   3.0000 + 3.0000i

B = sortrows(A)

B = 3×3 complex

   2.0000 + 1.0000i   4.0000 + 0.0000i   3.0000 + 3.0000i
   1.0000 + 2.0000i   3.0000 + 1.0000i   0.0000 + 1.0000i
   2.0000 +10.0000i   0.0000 + 6.0000i   2.0000 + 5.0000i

angle(A(1,1))

ans = 
1.1071

angle(A(3,1))

ans = 
0.4636

Use the 'real' option to sort the rows of A by their real part. Since A(2,1) and A(3,1) have equal real parts, sortrows uses the imaginary part to break the tie.

C = sortrows(A,'ComparisonMethod','real')

C = 3×3 complex

   1.0000 + 2.0000i   3.0000 + 1.0000i   0.0000 + 1.0000i
   2.0000 + 1.0000i   4.0000 + 0.0000i   3.0000 + 3.0000i
   2.0000 +10.0000i   0.0000 + 6.0000i   2.0000 + 5.0000i

imag(A(2,1))

ans = 
10

imag(A(3,1))

ans = 
1

Sort Rows of String Array

Create a 6-by-2 string array. Sort its rows in ascending alphabetical order based on the elements in the first column. When the first column contains repeated elements, use the second column to break the tie.

A = ["B" "Y"; "B" "Z"; "A" "Z"; ...
     "B" "X"; "A" "Y"; "A" "X"];
B1 = sortrows(A)

B1 = 6×2 string
    "A"    "X"
    "A"    "Y"
    "A"    "Z"
    "B"    "X"
    "B"    "Y"
    "B"    "Z"

Sort the rows again. This time, break the tie for elements in the first column by sorting the elements in the second column in descending alphabetical order.

B2 = sortrows(A,[1 2],["ascend" "descend"])

B2 = 6×2 string
    "A"    "Z"
    "A"    "Y"
    "A"    "X"
    "B"    "Z"
    "B"    "Y"
    "B"    "X"

Sort Rows of Table

Sort the rows of a table by variable values.

Create a table with four variables listing patient information for five people.

LastName = {'Smith';'Johnson';'Williams';'Jones';'Brown'};
Age = [38;43;38;40;49];
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];

tblA = table(Age,Height,Weight,BloodPressure,'RowNames',LastName)

tblA=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Smith       38       71       176       124     93  
    Johnson     43       69       163       109     77  
    Williams    38       64       131       125     83  
    Jones       40       67       133       117     75  
    Brown       49       64       119       122     80  

Sort the rows of the table. The sortrows function sorts the rows in ascending order first by the variable Age, and then by the variable Height to break the tie between the two rows with equal ages.

tblB = sortrows(tblA)

tblB=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Williams    38       64       131       125     83  
    Smith       38       71       176       124     93  
    Jones       40       67       133       117     75  
    Johnson     43       69       163       109     77  
    Brown       49       64       119       122     80  

Sort Rows of Table by Row Names

Create a table with four variables listing patient information for five people.

LastName = {'Smith';'Johnson';'Williams';'Jones';'Brown'};
Age = [38;43;38;40;49];
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];

tblA = table(Age,Height,Weight,BloodPressure,'RowNames',LastName)

tblA=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Smith       38       71       176       124     93  
    Johnson     43       69       163       109     77  
    Williams    38       64       131       125     83  
    Jones       40       67       133       117     75  
    Brown       49       64       119       122     80  

Sort the rows of the table in ascending order based on the row names, and return the index vector that describes how the rows were rearranged.

[tblB,index] = sortrows(tblA,'RowNames')

tblB=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Brown       49       64       119       122     80  
    Johnson     43       69       163       109     77  
    Jones       40       67       133       117     75  
    Smith       38       71       176       124     93  
    Williams    38       64       131       125     83  

index = 5×1

     5
     2
     4
     1
     3

Sort Rows of Table by Variables

Create a table with four variables listing patient information for five people.

LastName = {'Sweet';'Jacobson';'Wang';'Joiner';'Berger'};
Age = [38;43;38;40;49];
Height = [71;69;64;67;64];
Weight = [176;163;131;133;119];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];

tblA = table(Age,Height,Weight,BloodPressure,'RowNames',LastName)

tblA=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Sweet       38       71       176       124     93  
    Jacobson    43       69       163       109     77  
    Wang        38       64       131       125     83  
    Joiner      40       67       133       117     75  
    Berger      49       64       119       122     80  

Sort the rows of the table in ascending order by Height, and then in descending order by Weight.

tblB = sortrows(tblA,{'Height','Weight'},{'ascend','descend'})

tblB=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Wang        38       64       131       125     83  
    Berger      49       64       119       122     80  
    Joiner      40       67       133       117     75  
    Jacobson    43       69       163       109     77  
    Sweet       38       71       176       124     93  

Table with Missing Elements

Create a table with four variables listing patient information for five people. The Weight variable contains missing values.

LastName = {'Sweet';'Jacobson';'Wang';'Joiner';'Berger'};
Age = [38;43;38;40;49];
Height = [71;69;64;67;64];
Weight = [176;NaN;131;133;NaN];
BloodPressure = [124 93; 109 77; 125 83; 117 75; 122 80];
tblA = table(Age,Height,Weight,BloodPressure,'RowNames',LastName)

tblA=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Sweet       38       71       176       124     93  
    Jacobson    43       69       NaN       109     77  
    Wang        38       64       131       125     83  
    Joiner      40       67       133       117     75  
    Berger      49       64       NaN       122     80  

Sort the rows of the table in ascending order by Weight, placing the rows containing NaN first.

tblB = sortrows(tblA,'Weight','MissingPlacement','first')

tblB=5×4 table
                Age    Height    Weight    BloodPressure
                ___    ______    ______    _____________

    Jacobson    43       69       NaN       109     77  
    Berger      49       64       NaN       122     80  
    Wang        38       64       131       125     83  
    Joiner      40       67       133       117     75  
    Sweet       38       71       176       124     93  

Sort Rows of Timetable

Create a timetable, and sort the rows by row times.

TimeDuration = [hours(3) hours(2) hours(1) hours(5) hours(6)]';
TT = timetable(TimeDuration,[98;97.5;97.9;98.1;101],[120;111;119;117;118]);
           
B = sortrows(TT,'TimeDuration')

B=5×2 timetable
    TimeDuration    Var1    Var2
    ____________    ____    ____

    1 hr            97.9    119 
    2 hr            97.5    111 
    3 hr              98    120 
    5 hr            98.1    117 
    6 hr             101    118 

Input Arguments

A — Input array

column vector | matrix

Input array, specified as a column vector or matrix.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | cell | categorical | datetime | duration
Complex Number Support: Yes

column — Column sorting vector

nonzero integer scalar | vector of nonzero integers

Column sorting vector, specified as a nonzero integer scalar or vector of nonzero integers. Each specified integer value indicates a column to sort by. Negative integers indicate that the sort order is descending.

direction — Sorting direction

'ascend' (default) | 'descend' | string array | cell array of character vectors

Sorting direction, specified as either 'ascend', 'descend', or a string array or cell array of character vectors that specifies some combination of these values.

If direction is 'ascend' or 'descend', then the sorting direction applies for all column sorting vectors or sorting variables. If direction is a string array or cell array of character vectors, then each entry corresponds to a column sorting vector or a sorting variable.

If you specify both column and direction, then the direction determines the sorting direction and sortrows ignores the signs of the elements in column.

Example: sortrows(X,[2 3],{'ascend' 'descend'}) first sorts rows in ascending order according to column 2 of X. Then, rows with equal entries in column 2 are sorted in descending order according to column 3.

tblA — Input table

table | timetable

Input table, specified as a table or timetable. Each variable in tblA must be a valid input to sort or sortrows.

rowDimName — Name of first dimension of input table or timetable

string scalar | character vector

Name of the first dimension of the input table or timetable, specified as a string scalar or character vector.

• If tblA is a table with row names, then rowDimName is the name of the first dimension of the table. By default, the name of the first dimension is "Row". Dimension names are a property of tables. You can access the dimension names of tblA using tblA.Properties.DimensionNames.

• If tblA is a timetable, then rowDimName is the name of the vector of row times. You can specify its name when you create a timetable, such as Time or Date. You can also access the dimension names using tblA.Properties.DimensionNames.

Example: If a table T has row names, and you changed the name of the first dimension using T.Properties.DimensionName{1} = "Name", then sortrows(T,"Name") sorts the table by row name.

Example: If a timetable TT has a time vector named Date, then sortrows(TT,"Date") sorts the timetable on the dates and times that Date contains.

Data Types: string | char

vars — Sorting variables

scalar integer | vector of integers | variable name | string array of variable names | cell array of variable names | pattern scalar | logical vector

Sorting variables, specified as a scalar integer, vector of integers, variable name, string array of variable names, cell array of variable names, pattern scalar, or logical vector. vars indicates the table variables to sort by.

If you do not specify the direction argument, the sign of the elements in vars determines the sorting direction of the variables. If an element is a positive integer, then sortrows sorts the corresponding variable in tblA in ascending order. If an element is a negative integer, then sortrows sorts the corresponding variable in tblA in descending order. Otherwise, if you specify the direction argument, sortrows ignores the sign of vars and sorts the specified variables according to direction.

Example: sortrows(tblA,["Height","Weight"]) sorts the rows of tblA in ascending order, first by the variable Height, then by the variable Weight to break ties.

Example: sortrows(tblA,"X" + wildcardPattern) sorts the rows of tblA are in ascending order by the table variables whose names begin with the letter "X", using a wildcard pattern to match the remaining letters in their names.

Example: sortrows(tblA,[1 4]) sorts by the first variable of tblA in ascending order, then sorts by the fourth variable to break ties.

Example: sortrows(TT,["Time","X"]) sorts the row times of timetable TT in ascending order first, then sorts by the table variable X to break ties.

Data Types: double | single | string | char | cell | pattern | logical

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: sortrows(A,'MissingPlacement','last')

MissingPlacement — Placement of missing values

'auto' (default) | 'first' | 'last'

Placement of missing values (NaN, NaT, <undefined>, and missing) specified as the comma-separated pair consisting of 'MissingPlacement' and one of the following:

• 'auto' — Missing elements are placed last for ascending order and first for descending order.

• 'first' — Missing elements are placed first.

• 'last' — Missing elements are placed last.

ComparisonMethod — Element comparison method

'auto' (default) | 'real' | 'abs'

Element comparison method for numeric input, specified as 'ComparisonMethod' and one of these values:

• 'auto' — Sort rows of A by real(A) when A is real, and sort by abs(A) when A is complex.

• 'real' — Sort rows of A by real(A) when A is real or complex. If a column of A has elements with equal real parts, then use imag(A) to break ties.

• 'abs' — Sort rows of A by abs(A) when A is real or complex. If a column of A has elements with equal magnitude, then use angle(A) in the interval (-π,π] to break ties.

Output Arguments

B — Sorted array

column vector | matrix

Sorted array, returned as a column vector or matrix. B is the same size as A.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | cell | categorical | datetime | duration

tblB — Sorted table

table | timetable

Sorted table, returned as a table or timetable with the same variables as tblA.

index — Sort index

column vector

Sort index, returned as a column vector. The sort index describes the rearrangement of the rows in the input such that B = A(index,:).

The sortrows function uses a stable sorting algorithm. So, when the input contains repeated values, the sort index preserves the original order from the input, regardless of sorting direction. For example, if A = [1 1; 2 2; 1 2; 2 2], then [Ba,Ia] = sortrows(A,'ascend') returns the sort index Ia = [1; 3; 2; 4] and [Bd,Id] = sortrows(A,'descend') returns the sort index Id = [2; 4; 3; 1].

Data Types: double

Extended Capabilities

Tall Arrays

Calculate with arrays that have more rows than fit in memory.

The sortrows function supports tall arrays with the following usage notes and limitations:

• Sorting by row names is not supported.

For more information, see Tall Arrays.

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• Cell or string input array is not supported.

• If A is complex with all zero imaginary parts, then MATLAB^® might convert A to real(A) before calling sortrows(A). In this case, MATLAB sorts the rows of A by real(A), but the generated code sorts the rows of A by abs(A). To make the generated code match MATLAB, use sortrows(real(A)) or sortrows(A,'ComparisonMethod','real'). See Code Generation for Complex Data with Zero-Valued Imaginary Parts (MATLAB Coder).

• If tblA is a table or timetable, then the input argument vars must be constant.

• If tblA is a table or timetable, and it has a variable that is a cell array of character vectors with multiple columns, then you cannot sort tblA using the values in that variable.

• The vars input argument does not support pattern expressions.

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Usage notes and limitations:

• The first input argument must not be a cell array.

• If A is complex with all zero imaginary parts, then MATLAB might convert A to real(A) before calling sortrows(A). In this case, MATLAB sorts the rows of A by real(A), but the generated code sorts the rows of A by abs(A). To make the generated code match MATLAB, use sortrows(real(A)) or sortrows(A,'ComparisonMethod','real').

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The sortrows function supports GPU array input with these usage notes and limitations:

• Sorting cell arrays is not supported.

• Sparse inputs are not supported.

For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

Usage notes and limitations:

• Sorting cell arrays is not supported.

• Table, timetable, datetime and duration inputs are not supported.

For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a