rows2vars
Reorient table or timetable so that rows become variables
Description
T2 = rows2vars(T1)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.
T2 = rows2vars(T1,Name=Value)T2, set VariableNamesSource to the
variable of T1 that will provide the names of the variables of
T2.
Examples
Create tables, and then reorient their rows to be variables in new tables.
Load arrays of sample patient data from the patients.mat file. Create a table that contains the Age, Height, and Weight arrays from the sample file. Then create a subtable that has only the first five rows of the original table.
load patients
T1 = table(Age,Height,Weight);
T1 = T1(1:5,:)T1=5×3 table
Age Height Weight
___ ______ ______
38 71 176
43 69 163
38 64 131
40 67 133
49 64 119
To reorient the rows of T1, use the rows2vars function. Because the input table does not have any row names, the variables of the output table have default names, Var1 to VarN for N variables.
T2 = rows2vars(T1)
T2=3×6 table
OriginalVariableNames Var1 Var2 Var3 Var4 Var5
_____________________ ____ ____ ____ ____ ____
{'Age' } 38 43 38 40 49
{'Height'} 71 69 64 67 64
{'Weight'} 176 163 131 133 119
Create a table with row names using the LastName array from patients.mat. Again create a subtable that has only the first five rows of the original table.
T3 = table(Age,Height,Weight,RowNames=LastName); T3 = T3(1:5,:)
T3=5×3 table
Age Height Weight
___ ______ ______
Smith 38 71 176
Johnson 43 69 163
Williams 38 64 131
Jones 40 67 133
Brown 49 64 119
Reorient the rows of T3. If the input table has row names, then rows2vars turns the row names into the names of variables of the output table.
T4 = rows2vars(T3)
T4=3×6 table
OriginalVariableNames Smith Johnson Williams Jones Brown
_____________________ _____ _______ ________ _____ _____
{'Age' } 38 43 38 40 49
{'Height'} 71 69 64 67 64
{'Weight'} 176 163 131 133 119
Load a timetable from a sample MAT-file and display it.
load bostonTT.mat
BostonBoston=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 0.33
Reorient 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
To preserve original names from the input when rows2vars sets variable names of the output, use the VariableNamingRule name-value argument.
Load a timetable from a sample MAT-file and display it.
load bostonTT
BostonBoston=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 0.33
Reorient 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 by setting VariableNamingRule to "preserve".
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 access such variables using parentheses.
T.("2016-06-09 06:03:00")ans = 3×1
59.5000
0.1000
0.0500
Load arrays of sample patient data from the patients.mat file. Create a table that contains the Age, Height, Weight, LastName, and Location arrays from the sample file. Then create a subtable that has only the first five rows of the original table.
load patients
T1 = table(Age,Height,Weight,LastName,Location);
T1 = T1(1:5,:)T1=5×5 table
Age Height Weight LastName Location
___ ______ ______ ____________ _____________________________
38 71 176 {'Smith' } {'County General Hospital' }
43 69 163 {'Johnson' } {'VA Hospital' }
38 64 131 {'Williams'} {'St. Mary's Medical Center'}
40 67 133 {'Jones' } {'VA Hospital' }
49 64 119 {'Brown' } {'County General Hospital' }
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. The variables of this output table are cell arrays. They contain values that cannot be concatenated into arrays because they have incompatible data types.
T2 = rows2vars(T1,VariableNamesSource="LastName")T2=4×6 table
OriginalVariableNames Smith Johnson Williams Jones Brown
_____________________ ___________________________ _______________ _____________________________ _______________ ___________________________
{'Age' } {[ 38]} {[ 43]} {[ 38]} {[ 40]} {[ 49]}
{'Height' } {[ 71]} {[ 69]} {[ 64]} {[ 67]} {[ 64]}
{'Weight' } {[ 176]} {[ 163]} {[ 131]} {[ 133]} {[ 119]}
{'Location'} {'County General Hospital'} {'VA Hospital'} {'St. Mary's Medical Center'} {'VA Hospital'} {'County General Hospital'}
Load arrays of sample patient data from the patients.mat file. Create a table that contains the Age, Height, Weight, Smoker, and Location arrays from the sample file and uses the LastName array as row names. Then create a subtable that has only the first five rows of the original table.
load patients
T1 = table(Age,Height,Weight,Smoker,Location,RowNames=LastName);
T1 = T1(1:5,:)T1=5×5 table
Age Height Weight Smoker Location
___ ______ ______ ______ _____________________________
Smith 38 71 176 true {'County General Hospital' }
Johnson 43 69 163 false {'VA Hospital' }
Williams 38 64 131 false {'St. Mary's Medical Center'}
Jones 40 67 133 false {'VA Hospital' }
Brown 49 64 119 false {'County General Hospital' }
Reorient specified variables from T1 and discard the rest.
T2 = rows2vars(T1,DataVariables=["Age" "Height" "Weight"])
T2=3×6 table
OriginalVariableNames Smith Johnson Williams Jones Brown
_____________________ _____ _______ ________ _____ _____
{'Age' } 38 43 38 40 49
{'Height'} 71 69 64 67 64
{'Weight'} 176 163 131 133 119
You also can specify data variables by position in the input table. To specify positions, use a numeric array.
T3 = rows2vars(T1,DataVariables=1:3)
T3=3×6 table
OriginalVariableNames Smith Johnson Williams Jones Brown
_____________________ _____ _______ ________ _____ _____
{'Age' } 38 43 38 40 49
{'Height'} 71 69 64 67 64
{'Weight'} 176 163 131 133 119
Input Arguments
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.
Example: VariableNamingRule="preserve" preserves original names
taken from T1, without modifying them to be valid MATLAB® identifiers.
Variable in T1 that contains variable names,
specified as a string scalar, character vector, positive integer, or
logical vector. The rows2vars function interprets
the value of VariableNamesSource as shown in the
table.
Value of
| Meaning |
|---|---|
String scalar or character vector | 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
table 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
VariableNamesSourcecan 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.
The value of VariableNamesSource cannot specify a
variable that is also specified by the DataVariables
name-value argument.
Selected variables from T1, specified as a string
array, character vector, cell array of character vectors, pattern
scalar, positive integer, vector of positive integers, or logical
vector. 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.
The value of DataVariables cannot specify a
variable that is also specified by the
VariableNamesSource name-value argument.
Rule for naming variables in T2, specified as
"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,
|
Output Arguments
Reoriented output table.
If the input is a timetable, then the output is a table whose variable names represent the row times of the input timetable.
Extended Capabilities
Usage notes and limitations:
Timetables are not supported.
The input table cannot be variable-size.
The
VariableNamesSourcename-value argument is not supported.The value of the
DataVariablesname-value argument must be constant.The value of the
DataVariablesname-value argument does not support pattern expressions.The value of the
VariableNamingRulename-value argument must be constant.If you assign row names to the input table, then the vector of row names must be constant.
Refer to the usage notes and limitations in the C/C++ Code Generation section. The same usage notes and limitations apply to GPU code generation.
Thread-Based Environment
Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.
Version History
Introduced in R2018a
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
How to Get Best Site Performance
Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.
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
- United Kingdom (English)