array2timetable

Convert homogeneous array to timetable

Syntax

TT = array2timetable(X,'RowTimes',rowTimes)

TT = array2timetable(X,'SampleRate',Fs)

TT = array2timetable(X,'TimeStep',dt)

TT = array2timetable(___,'StartTime',t0)

T = array2timetable(X,Name,Value)

Description

TT = array2timetable(X,'RowTimes',rowTimes) converts an input array to a timetable. The input array X is an M-by-N array and the vector rowTimes is an M-by-1 vector of datetime or duration values. Each column of X becomes a variable of TT. The time values in rowTimes label the rows of the timetable. TT is an M-by-N timetable.

For more information on creating and using timetables, see Timetables.

TT = array2timetable(X,'SampleRate',Fs) uses the sample rate Fs to calculate regularly spaced row times. Fs is a numeric scalar that specifies the number of samples per second (Hz). The first row time is zero seconds.

TT = array2timetable(X,'TimeStep',dt) uses the time step dt to calculate regularly spaced row times. dt is a duration or calendar duration value that specifies the length of time between consecutive row times. The first row time is zero seconds.

TT = array2timetable(___,'StartTime',t0) specifies start time t0, instead of zero seconds, as the first row time. You can use this syntax when you create a regular timetable using either the 'SampleRate' or 'TimeStep' name-value pair arguments from either of the previous two syntaxes.

T = array2timetable(X,Name,Value) creates a timetable from an array, X, with additional options specified by one or more Name,Value pair arguments.

For example, you can specify variable names to include in the timetable.

Examples

Convert Array to Timetable

Convert an array to a timetable. Add a vector of durations as the row times.

X = rand(5,3);
Time = seconds(1:5);
TT = array2timetable(X,'RowTimes',Time)

TT=5×3 timetable
    Time       X1         X2         X3   
    _____    _______    _______    _______

    1 sec    0.81472    0.09754    0.15761
    2 sec    0.90579     0.2785    0.97059
    3 sec    0.12699    0.54688    0.95717
    4 sec    0.91338    0.95751    0.48538
    5 sec    0.63236    0.96489    0.80028

Return the size of the timetable. TT contains five rows and three variables. The set of row times is a table property. The row times are not contained in a table variable.

size(TT)

ans = 1×2

     5     3

Specify Sample Rate

Specify a sample rate of 500 Hz, and convert an array to a timetable.

X = rand(5,3);
TT = array2timetable(X,'SampleRate',500)

TT=5×3 timetable
      Time         X1         X2         X3   
    _________    _______    _______    _______

    0 sec        0.81472    0.09754    0.15761
    0.002 sec    0.90579     0.2785    0.97059
    0.004 sec    0.12699    0.54688    0.95717
    0.006 sec    0.91338    0.95751    0.48538
    0.008 sec    0.63236    0.96489    0.80028

Specify Time Step

Specify a time step of 0.5 seconds, and convert an array to a timetable.

X = rand(5,3);
TT = array2timetable(X,'TimeStep',seconds(0.5))

TT=5×3 timetable
     Time        X1         X2         X3   
    _______    _______    _______    _______

    0 sec      0.81472    0.09754    0.15761
    0.5 sec    0.90579     0.2785    0.97059
    1 sec      0.12699    0.54688    0.95717
    1.5 sec    0.91338    0.95751    0.48538
    2 sec      0.63236    0.96489    0.80028

Specify Start Time

Specify a time step of 15 seconds, and a start time of 5 minutes.

X = rand(5,3);
TT = array2timetable(X,'TimeStep',seconds(15),'StartTime',minutes(5))

TT=5×3 timetable
      Time        X1         X2         X3   
    ________    _______    _______    _______

    5 min       0.81472    0.09754    0.15761
    5.25 min    0.90579     0.2785    0.97059
    5.5 min     0.12699    0.54688    0.95717
    5.75 min    0.91338    0.95751    0.48538
    6 min       0.63236    0.96489    0.80028

Specify Variable Names

Convert an array to a timetable. Specify the row times as a datetime vector. Specify names for the timetable variables.

X = randi([70 90],5,3);
Time = datetime(2016,7,1:5);
varNames = {'Temp1','Temp2','Temp3'};
TT = array2timetable(X,'RowTimes',Time,'VariableNames',varNames)

TT=5×3 timetable
       Time        Temp1    Temp2    Temp3
    ___________    _____    _____    _____

    01-Jul-2016     87       72       73  
    02-Jul-2016     89       75       90  
    03-Jul-2016     72       81       90  
    04-Jul-2016     89       90       80  
    05-Jul-2016     83       90       86  

Input Arguments

X — Input matrix

matrix

Input matrix.

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

rowTimes — Times associated with rows of timetable

datetime vector | duration vector

Times associated with rows of a timetable, specified as a datetime vector or a duration vector. Each time labels a row in the output timetable. The time values in rowTimes do not need to be unique, sorted, or regular.

Fs — Sample rate

numeric scalar

Sample rate, specified as a numeric scalar. Fs specifies the number of samples per second (Hz).

dt — Time step

duration scalar | calendar duration scalar

Time step, specified as a duration or calendar duration scalar.

Data Types: duration | calendarDuration

t0 — Start time

datetime scalar | duration scalar

Start time, specified as a datetime scalar or duration scalar.

• If t0 is a datetime value, then the row times of TT are datetime values.

• If t0 is a duration, then the row times are durations.

If the time step dt is a calendar duration value, then t0 must be a datetime value.

Data Types: datetime | duration

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: TT = array2timetable(X,'RowTimes',Time,'VariableNames',{'Latitude','Longitude'}) creates a timetable from input array X, with row times specified by Time, and names the corresponding timetable variables Latitude and Longitude.

VariableNames — Variable names

cell array of character vectors | string array

Variable names, specified as a cell array of character vectors or a string array, whose elements are nonempty and distinct. The number of variable names must equal the number of columns of the input array.

Variable names can have any Unicode^® characters, including spaces and non-ASCII characters. However, a variable name cannot match any table dimension name or the reserved names 'Properties', 'RowNames', 'VariableNames', or ':'.

DimensionNames — Dimension names

two-element cell array of character vectors | two-element string array

Since R2021a

Dimension names, specified as a two-element cell array of character vectors or two-element string array whose elements are nonempty and distinct.

Dimension names can have any Unicode characters, including spaces and non-ASCII characters. However, a dimension name cannot match any table variable name or the reserved names 'Properties', 'RowNames', 'VariableNames', or ':'.

As an alternative, in all releases you can specify dimension names by setting the DimensionNames property of the table.

Output Arguments

TT — Output timetable

timetable

Output timetable. The timetable can store metadata such as descriptions, variable units, variable names, and row times. For more information, see the Properties section of timetable.

Tips

• In certain cases, you can call array2timetable with a syntax that specifies a regular time step between row times, and yet array2timetable returns an irregular timetable. This result occurs when you specify the time step using a calendar unit of time and there is a row time that introduces an irregular step. For example, if you create a timetable with a time step of one calendar month, starting on January 31, 2019, then it is irregular with respect to months.

  stime = datetime(2019,1,31);
  tstep = calmonths(1);
  X = [1:3]';
  TT = array2timetable(X,'TimeStep',tstep,'StartTime',stime)
  

  TT =
  
    3×1 timetable
  
         Time        X
      ___________    _
  
      31-Jan-2019    1
      28-Feb-2019    2
      31-Mar-2019    3
  

  There are other cases where irregularities are due to shifts from Daylight Saving Time (DST) or to datetime values that are leap seconds. This table specifies the dates, times, and time steps that can produce irregular results unexpectedly.

  Row Time Value	Time Step
  Start time specified as the 29th, 30th, or 31st day of the month.	Number of calendar months or quarters.
  Start time specified as February 29.	Number of calendar years.
  Any datetime value occurring between 1:00 a.m. and 2:00 a.m. on a day shifting from DST to standard time (when such values have a time zone that observes DST).	Number of calendar days or months.
  Any datetime value that is a leap second (when the time zone for such values is the UTCLeapSeconds time zone). For the list of leap seconds, see leapseconds.	Time step specified in any calendar unit (days, weeks, months, quarters, or years).

Extended Capabilities

Tall Arrays

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

The array2timetable 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:

• In generated code, you must specify the 'VariableNames' name-value pair argument when using this function.

• If you specify regular row times by using the 'SampleRate', 'TimeStep', or 'StartTime' name-value pair argument, then the value must be a constant at compile time for the row times to be regular. Otherwise, the row times are considered to be irregular in generated code.

For more information, see Code Generation for Timetables (MATLAB Coder) and Timetable Limitations for Code Generation (MATLAB Coder).

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

Version History

Introduced in R2016b

R2021a: 'SamplingRate' will be removed

The 'SamplingRate' name-value argument will be removed in a future release. Use 'SampleRate' instead. The corresponding timetable property is also named SampleRate.

For backward compatibility, you still can specify 'SamplingRate' as the name of the name-value argument. However, the value is assigned to the SampleRate property.

R2019b: Variable names can contain leading and trailing whitespace characters

Table and timetable variable names with leading or trailing whitespace characters are not modified.

In previous releases, leading and trailing whitespace characters were deleted from variable names when you specified them using the 'VariableNames' name-value pair argument, or assigned them to the VariableNames property.

To manually remove such characters, first use the strtrim function on the names, then assign them as variable names to the table or timetable.