Reorient table or timetable so that rows become variables
collapse all in page
Syntax
T2 = rows2vars(T1)
T2 = rows2vars(T1,Name,Value)
Description
example
T2 = rows2vars(T1) reorients the rows of T1, so that they become variables in the output table T2. If rows2vars can concatenate the contents of the rows of T1, then the corresponding variables of T2 are arrays. Otherwise, the variables of T2 are cell arrays. The rows2vars function copies the names of the variables of T1 to a new variable of T2. The output is always a table, though T1 can be either a table or a timetable.
For example, if T1 has two rows and five variables, then T2 has five rows, two variables containing the original data from T1, and a new variable named OriginalVariableNames. In T2, the variable OriginalVariableNames contains the names of the table variables from T1.
If T1 has row names or row times, then those names or times become the variable names of T2. Otherwise, rows2vars generates names Var1,…,VarN as the variable names of T2.
Conceptually, you can think of T2 as being like a transpose of T1. Technically, T2 is not a true transpose of the input table because rows2vars adds a new variable to T2. Also, the variables of T1 might have incompatible data types, in which case the "transposed" rows from T1 become cell arrays in T2.
example
T2 = rows2vars(T1,Name,Value) specifies additional arguments using one or more name-value pair arguments. For example, you can use the 'VariableNamesSource' name-value pair argument to specify the source of the variable names of T2.
Examples
collapse all
Reorient Rows as Variables
Open Live Script
Create tables, and then reorient their rows to be variables in new tables.
Load arrays of data from the patients.mat file. Create a table that contains the LastName, Gender, Age, Height, and Weight variables.
load patientsT1 = table(LastName,Gender,Age,Height,Weight);head(T1,3) LastName Gender Age Height Weight ____________ __________ ___ ______ ______ {'Smith' } {'Male' } 38 71 176 {'Johnson' } {'Male' } 43 69 163 {'Williams'} {'Female'} 38 64 131 Reorient the rows of T1 to be the variables of the output table.
T2 = rows2vars(T1);
Display the first four variables of T2. The first variable of T2 contains the names of the variables of T1. The remaining variables of T2 correspond to rows of T1. Since T1 did not have any row labels, the variables of T2 have default names, Var1 to VarN for N variables.
T2(:,1:4)
ans=5×4 table OriginalVariableNames Var1 Var2 Var3 _____________________ _________ ___________ ____________ {'LastName'} {'Smith'} {'Johnson'} {'Williams'} {'Gender' } {'Male' } {'Male' } {'Female' } {'Age' } {[ 38]} {[ 43]} {[ 38]} {'Height' } {[ 71]} {[ 69]} {[ 64]} {'Weight' } {[ 176]} {[ 163]} {[ 131]}Create a table with row names. If a table has row names, then rows2vars turns the row names into the names of variables.
T3 = table(Gender,Age,Height,Weight,'RowNames',LastName);head(T3,3) Gender Age Height Weight __________ ___ ______ ______ Smith {'Male' } 38 71 176 Johnson {'Male' } 43 69 163 Williams {'Female'} 38 64 131 Reorient the rows of T3.
T4 = rows2vars(T3);T4(:,1:4)
ans=4×4 table OriginalVariableNames Smith Johnson Williams _____________________ ________ ________ __________ {'Gender'} {'Male'} {'Male'} {'Female'} {'Age' } {[ 38]} {[ 43]} {[ 38]} {'Height'} {[ 71]} {[ 69]} {[ 64]} {'Weight'} {[ 176]} {[ 163]} {[ 131]}Reorient Timetable Rows
Open Live Script
Load a timetable and display it.
load bostonTTBostonBoston=6×3 timetable Time Temp WindSpeed Rain ___________________ ____ _________ ____ 2016-06-09 06:03:00 59.5 0.1 0.05 2016-06-09 12:00:23 63 2.3 0.08 2016-06-09 18:02:57 61.7 3.1 0.13 2016-06-10 06:01:47 55.4 5.7 0.15 2016-06-10 12:06:00 62.3 2.6 0.87 2016-06-10 18:02:57 58.8 6.2 0.33Reorient it so that its rows become variables in the output. The rows2vars function turns the row times into names, but modifies them so that they are valid variable names. Also, the output argument returned by rows2vars is always a table, even when the input argument is a timetable.
T = rows2vars(Boston)
Warning: Table variable names that were not valid MATLAB identifiers have been modified. Since table variable names must be unique, any table variable names that happened to match the new identifiers also have been modified.To use the original row names as new variable names, set 'VariableNamingRule' to 'preserve'.
T=3×7 table OriginalVariableNames x2016_06_0906_03_00 x2016_06_0912_00_23 x2016_06_0918_02_57 x2016_06_1006_01_47 x2016_06_1012_06_00 x2016_06_1018_02_57 _____________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ {'Temp' } 59.5 63 61.7 55.4 62.3 58.8 {'WindSpeed'} 0.1 2.3 3.1 5.7 2.6 6.2 {'Rain' } 0.05 0.08 0.13 0.15 0.87 0.33 Preserve Original Names
Open Live Script
Starting in R2020a, you can take names from the input table or timetable and use them as variable names in the output table without modification. To preserve the original names, use the 'VariableNamingRule' name-value pair argument.
Load a timetable and display it.
load bostonTTBostonBoston=6×3 timetable Time Temp WindSpeed Rain ___________________ ____ _________ ____ 2016-06-09 06:03:00 59.5 0.1 0.05 2016-06-09 12:00:23 63 2.3 0.08 2016-06-09 18:02:57 61.7 3.1 0.13 2016-06-10 06:01:47 55.4 5.7 0.15 2016-06-10 12:06:00 62.3 2.6 0.87 2016-06-10 18:02:57 58.8 6.2 0.33Reorient the timetable so that its row times become variable names in the output table. Convert the datetime values to strings and preserve the resulting names using the 'VariableNamingRule' name-value pair.
T = rows2vars(Boston,'VariableNamingRule','preserve')
T=3×7 table OriginalVariableNames 2016-06-09 06:03:00 2016-06-09 12:00:23 2016-06-09 18:02:57 2016-06-10 06:01:47 2016-06-10 12:06:00 2016-06-10 18:02:57 _____________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ {'Temp' } 59.5 63 61.7 55.4 62.3 58.8 {'WindSpeed'} 0.1 2.3 3.1 5.7 2.6 6.2 {'Rain' } 0.05 0.08 0.13 0.15 0.87 0.33 The variable names in T are not valid MATLAB® identifiers because the dates start with a number. However, you can use dot notation to refer to such variables, using parentheses.
T.('2016-06-09 06:03:00')ans = 3×1 59.5000 0.1000 0.0500Names of Output Table Variables
Open Live Script
Read data from a spreadsheet into a table. Display the first three rows.
T1 = readtable('patients.xls');head(T1,3) LastName Gender Age Location Height Weight Smoker Systolic Diastolic SelfAssessedHealthStatus ____________ __________ ___ _____________________________ ______ ______ ______ ________ _________ ________________________ {'Smith' } {'Male' } 38 {'County General Hospital' } 71 176 true 124 93 {'Excellent'} {'Johnson' } {'Male' } 43 {'VA Hospital' } 69 163 false 109 77 {'Fair' } {'Williams'} {'Female'} 38 {'St. Mary's Medical Center'} 64 131 false 125 83 {'Good' } Reorient the rows of T1 to be variables of a new table, T2. Specify that the LastName variable from T1 is the source of the names of the variables of T2.
T2 = rows2vars(T1,'VariableNamesSource','LastName');
Display the first four variables of T2. The first variable of T2 contains the names of the variables of T1. The remaining variables of T2 correspond to rows of T1.
T2(:,1:4)
ans=9×4 table OriginalVariableNames Smith Johnson Williams ____________________________ ___________________________ _______________ _____________________________ {'Gender' } {'Male' } {'Male' } {'Female' } {'Age' } {[ 38]} {[ 43]} {[ 38]} {'Location' } {'County General Hospital'} {'VA Hospital'} {'St. Mary's Medical Center'} {'Height' } {[ 71]} {[ 69]} {[ 64]} {'Weight' } {[ 176]} {[ 163]} {[ 131]} {'Smoker' } {[ 1]} {[ 0]} {[ 0]} {'Systolic' } {[ 124]} {[ 109]} {[ 125]} {'Diastolic' } {[ 93]} {[ 77]} {[ 83]} {'SelfAssessedHealthStatus'} {'Excellent' } {'Fair' } {'Good' }Display the data in T2.Smith. In this example, every variable of T2 is a 9-by-1 cell array, because the values in the rows of T1 cannot be concatenated into arrays.
T2.Smith
ans=9×1 cell array {'Male' } {[ 38]} {'County General Hospital'} {[ 71]} {[ 176]} {[ 1]} {[ 124]} {[ 93]} {'Excellent' }Specify Data Variables
Open Live Script
Read data from a spreadsheet into a table. Use the first column of the spreadsheet as the row names of the table. Display the first three rows.
T1 = readtable('patients.xls','ReadRowNames',true);head(T1,3)
Gender Age Location Height Weight Smoker Systolic Diastolic SelfAssessedHealthStatus __________ ___ _____________________________ ______ ______ ______ ________ _________ ________________________ Smith {'Male' } 38 {'County General Hospital' } 71 176 true 124 93 {'Excellent'} Johnson {'Male' } 43 {'VA Hospital' } 69 163 false 109 77 {'Fair' } Williams {'Female'} 38 {'St. Mary's Medical Center'} 64 131 false 125 83 {'Good' } Reorient specified variables from T1 and discard the rest. To specify data variables by name, use a cell array of character vectors.
T2 = rows2vars(T1,'DataVariables',{'Gender','Age','Height','Weight'});T2(:,1:4)
ans=4×4 table OriginalVariableNames Smith Johnson Williams _____________________ ________ ________ __________ {'Gender'} {'Male'} {'Male'} {'Female'} {'Age' } {[ 38]} {[ 43]} {[ 38]} {'Height'} {[ 71]} {[ 69]} {[ 64]} {'Weight'} {[ 176]} {[ 163]} {[ 131]}You also can specify data variables by position in the input table. To specify positions of variables, use a numeric array.
T3 = rows2vars(T1,'DataVariables',[1 2 6:9]);T3(:,1:4)ans=6×4 table OriginalVariableNames Smith Johnson Williams ____________________________ _____________ ________ __________ {'Gender' } {'Male' } {'Male'} {'Female'} {'Age' } {[ 38]} {[ 43]} {[ 38]} {'Smoker' } {[ 1]} {[ 0]} {[ 0]} {'Systolic' } {[ 124]} {[ 109]} {[ 125]} {'Diastolic' } {[ 93]} {[ 77]} {[ 83]} {'SelfAssessedHealthStatus'} {'Excellent'} {'Fair'} {'Good' }Input Arguments
collapse all
T1 — Input table
table | timetable
Input table, specified as a table or timetable.
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: 'VariableNamingRule','preserve' preserves original names taken from T1, without modifying them to be valid MATLAB® identifiers.
VariableNamesSource — Variable in T1 that contains variable names
character vector | string scalar | positive integer | logical vector
Variable in T1 that contains variable names, specified as the comma-separated pair consisting of 'VariableNamesSource' and a character vector, string scalar, positive integer, or logical vector. The rows2vars function interprets the value of 'VariableNamesSource' as shown in the table.
Value of | Meaning |
|---|---|
Character vector or string scalar | Name of a variable in the input table |
Integer | The nth variable in T1. |
Logical vector, whose length equals the number of variables in | The |
While the value of 'VariableNamesSource' must be a name, number, or logical array that specifies a table variable, the variable itself can have any data type, with these limitations.
The values contained in the specified table variable must have a data type that allows the values to be converted to strings. For example, the value of
'VariableNamesSource'can be the name of a table variable that contains adatetimearray, becausedatetimevalues can be converted to strings.The number of names taken from the specified table variable must match the number of rows of the input table.
DataVariables — Selected variables from T1
string array | character vector | cell array of character vectors | pattern scalar | positive integer | vector of positive integers | logical vector | subscript object
Selected variables from T1, specified as the comma-separated pair consisting of 'DataVariables' and a string array, character vector, cell array of character vectors, pattern scalar, positive integer, vector of positive integers, logical vector, or subscript object. The rows2vars function selects the variables specified by the value of 'DataVariables' and reorients only those variables to become the rows of T2. The remaining variables of T1 are discarded.
VariableNamingRule — Rule for naming variables in T2
'modify' (default) | 'preserve'
Rule for naming variables in T2, specified as the comma-separated pair consisting of 'VariableNamingRule' and either the value 'modify' or 'preserve'.
The values of 'VariableNamingRule' specify the following rules for naming variable in the output table or timetable.
Value of | Rule |
|---|---|
| Modify names taken from the input table or timetable so that the corresponding variable names in the output are also valid MATLAB identifiers. |
| Preserve original names taken from the input table or timetable. The corresponding variable names in the output can have any Unicode® characters, including spaces and non-ASCII characters. Note: In some cases,
|
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
Timetables are not supported.
The input table cannot be variable-size.
The
'VariableNamesSource'name-value argument is not supported.The value of the
'DataVariables'name-value argument must be constant.The value of the
'DataVariables'name-value argument does not support pattern expressions.The value of the
'VariableNamingRule'name-value argument must be constant.If you assign row names to the input table, then the vector of row names must be constant.
Thread-Based Environment
Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.
Version History
Introduced in R2018a
See Also
inner2outer | innerjoin | join | outerjoin | stack | unstack | vartype
MATLAB Command
You clicked a link that corresponds to this MATLAB command:
Run the command by entering it in the MATLAB Command Window. Web browsers do not support MATLAB commands.
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
You can also select a web site from the following list:
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
Europe
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- Deutsch
- English
- Français
- United Kingdom (English)
Contact your local office
