mergevars

Combine table or timetable variables into multicolumn variable

Syntax

T2 = mergevars(T1,vars)

T2 = mergevars(T1,vars,Name,Value)

Description

T2 = mergevars(T1,vars) combines the table variables specified by vars to create one multicolumn variable in T2. All other variables from T1 are unaltered. You can specify variables by name, by position, or using logical indices.

For example, if T1 has variables named var3 and var5, then you can combine them into a variable that has two columns by using T2 = mergevars(T1,["var3","var5"]).

By default, the name of the merged variable in T2 takes the form VarN, where N is the position of the merged variable. For example, if the merged variable is the third variable in T2, then its name is Var3.

To split multicolumn variables, use the splitvars function.

T2 = mergevars(T1,vars,Name,Value) specifies options using one or more name-value arguments in addition to the input arguments in the previous syntax. For example, to specify a name for the merged variable, set NewVariableName to the name that you specify.

Examples

Merge Variables

Create a table from workspace variables.

A = [1:3]';
B = [5 11 12]';
C = [3.14 2.72 1.37]';
D = ["a";"b";"c"];
T1 = table(A,B,C,D)

T1=3×4 table
    A    B      C       D 
    _    __    ____    ___

    1     5    3.14    "a"
    2    11    2.72    "b"
    3    12    1.37    "c"

Merge the second and third variables. The new variable has two columns.

T2 = mergevars(T1,[2 3])

T2=3×3 table
    A       Var2        D 
    _    __________    ___

    1     5    3.14    "a"
    2    11    2.72    "b"
    3    12    1.37    "c"

New Name for Merged Variable

Create a table using arrays of data from the patients.mat file.

load patients
T1 = table(Age,Height,Weight,Systolic,Diastolic)

T1=100×5 table
    Age    Height    Weight    Systolic    Diastolic
    ___    ______    ______    ________    _________

    38       71       176        124          93    
    43       69       163        109          77    
    38       64       131        125          83    
    40       67       133        117          75    
    49       64       119        122          80    
    46       68       142        121          70    
    33       64       142        130          88    
    40       68       180        115          82    
    28       68       183        115          78    
    31       66       132        118          86    
    45       68       128        114          77    
    42       66       137        115          68    
    25       71       174        127          74    
    39       72       202        130          95    
    36       65       129        114          79    
    48       71       181        130          92    
      ⋮

Merge the variables Systolic and Diastolic into one variable with two columns. Name it BloodPressure.

T2 = mergevars(T1,["Systolic","Diastolic"], ...
               "NewVariableName","BloodPressure")

T2=100×4 table
    Age    Height    Weight    BloodPressure
    ___    ______    ______    _____________

    38       71       176       124     93  
    43       69       163       109     77  
    38       64       131       125     83  
    40       67       133       117     75  
    49       64       119       122     80  
    46       68       142       121     70  
    33       64       142       130     88  
    40       68       180       115     82  
    28       68       183       115     78  
    31       66       132       118     86  
    45       68       128       114     77  
    42       66       137       115     68  
    25       71       174       127     74  
    39       72       202       130     95  
    36       65       129       114     79  
    48       71       181       130     92  
      ⋮

Merged Variable into Table

Read a table from a spreadsheet. To specify the data types of the columns that you read from the spreadsheet, use an import options object. Display the first eight rows of the output table.

opts = detectImportOptions("outages.csv");
opts.VariableTypes = ["categorical","datetime","double", ...
                      "double","datetime","categorical"];
T1 = readtable("outages.csv",opts)

T1=1468×6 table
     Region         OutageTime        Loss     Customers     RestorationTime          Cause     
    _________    ________________    ______    __________    ________________    _______________

    SouthWest    2002-02-01 12:18    458.98    1.8202e+06    2002-02-07 16:50    winter storm   
    SouthEast    2003-01-23 00:49    530.14    2.1204e+05                 NaT    winter storm   
    SouthEast    2003-02-07 21:15     289.4    1.4294e+05    2003-02-17 08:14    winter storm   
    West         2004-04-06 05:44    434.81    3.4037e+05    2004-04-06 06:10    equipment fault
    MidWest      2002-03-16 06:18    186.44    2.1275e+05    2002-03-18 23:23    severe storm   
    West         2003-06-18 02:49         0             0    2003-06-18 10:54    attack         
    West         2004-06-20 14:39    231.29           NaN    2004-06-20 19:16    equipment fault
    West         2002-06-06 19:28    311.86           NaN    2002-06-07 00:51    equipment fault
    NorthEast    2003-07-16 16:23    239.93         49434    2003-07-17 01:12    fire           
    MidWest      2004-09-27 11:09    286.72         66104    2004-09-27 16:37    equipment fault
    SouthEast    2004-09-05 17:48    73.387         36073    2004-09-05 20:46    equipment fault
    West         2004-05-21 21:45    159.99           NaN    2004-05-22 04:23    equipment fault
    SouthEast    2002-09-01 18:22    95.917         36759    2002-09-01 19:12    severe storm   
    SouthEast    2003-09-27 07:32       NaN    3.5517e+05    2003-10-04 07:02    severe storm   
    West         2003-11-12 06:12    254.09    9.2429e+05    2003-11-17 02:04    winter storm   
    NorthEast    2004-09-18 05:54         0             0                 NaT    equipment fault
      ⋮

Merge Cause, Loss, and RestorationTime. Because these variables have different types, merge them into a table that is nested in the output table.

T2 = mergevars(T1,["Cause","Loss","RestorationTime"],...
               "NewVariableName","LossData","MergeAsTable",true)

T2=1468×4 table
     Region         OutageTime       Customers                       LossData                   
    _________    ________________    __________    _____________________________________________

                                                        Cause          Loss     RestorationTime 
                                                   _______________    ______    ________________
                                                                                                
    SouthWest    2002-02-01 12:18    1.8202e+06    winter storm       458.98    2002-02-07 16:50
    SouthEast    2003-01-23 00:49    2.1204e+05    winter storm       530.14                 NaT
    SouthEast    2003-02-07 21:15    1.4294e+05    winter storm        289.4    2003-02-17 08:14
    West         2004-04-06 05:44    3.4037e+05    equipment fault    434.81    2004-04-06 06:10
    MidWest      2002-03-16 06:18    2.1275e+05    severe storm       186.44    2002-03-18 23:23
    West         2003-06-18 02:49             0    attack                  0    2003-06-18 10:54
    West         2004-06-20 14:39           NaN    equipment fault    231.29    2004-06-20 19:16
    West         2002-06-06 19:28           NaN    equipment fault    311.86    2002-06-07 00:51
    NorthEast    2003-07-16 16:23         49434    fire               239.93    2003-07-17 01:12
    MidWest      2004-09-27 11:09         66104    equipment fault    286.72    2004-09-27 16:37
    SouthEast    2004-09-05 17:48         36073    equipment fault    73.387    2004-09-05 20:46
    West         2004-05-21 21:45           NaN    equipment fault    159.99    2004-05-22 04:23
    SouthEast    2002-09-01 18:22         36759    severe storm       95.917    2002-09-01 19:12
    SouthEast    2003-09-27 07:32    3.5517e+05    severe storm          NaN    2003-10-04 07:02
    West         2003-11-12 06:12    9.2429e+05    winter storm       254.09    2003-11-17 02:04
    NorthEast    2004-09-18 05:54             0    equipment fault         0                 NaT
      ⋮

Input Arguments

T1 — Input table

table | timetable

Input table, specified as a table or timetable.

vars — Variables in input table

string array | character vector | cell array of character vectors | pattern scalar | numeric array | logical array

Variables in the input table, specified as a string array, character vector, cell array of character vectors, pattern scalar, numeric array, or logical array.

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: T2 = mergevars(T1,vars,NewVariableName="MergedResults")

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

Example: T2 = mergevars(T1,vars,"MergeAsTable",true)

NewVariableName — Name of merged variable

character vector | string scalar

Name of the merged variable, specified as a character vector or string scalar.

MergeAsTable — Flag to merge variables into table

false or 0 (default) | true or 1

Flag to merge variables into a table, specified as a numeric or logical 1 (true) or 0 (false). Set this flag to true or 1 to merge the specified variables into a table that is nested into a variable of the output table. Use this argument to combine variables that cannot be concatenated into an array.

The default value of false causes mergevars to merge the specified variables into one multicolumn array that is a variable of the output table.

Extended Capabilities

Tall Arrays

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

The mergevars function fully supports tall arrays. For more information, see Tall Arrays.

C/C++ Code Generation

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

Usage notes and limitations:

• The vars input argument does not support pattern expressions.

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.

Version History

Introduced in R2018a