tabulate

Frequency table

Syntax

tabulate(x)

tbl = tabulate(x)

Description

tabulate(x) displays a frequency table of the data in the vector x. For each unique value in x, the tabulate function shows the number of instances and percentage of that value in x. See tbl.

tbl = tabulate(x) returns the frequency table tbl as a numeric matrix when x is numeric and as a cell array otherwise.

Examples

Tabulate Data Vector

Create a frequency table for a vector of data.

Load the patients data set. Display the first five entries of the Gender variable. Each value indicates the gender of a patient.

load patients
Gender(1:5)

ans = 5x1 cell array
    {'Male'  }
    {'Male'  }
    {'Female'}
    {'Female'}
    {'Female'}

Generate a frequency table that shows the number and percentage of Male and Female patients in the data set.

tabulate(Gender)

   Value    Count   Percent
    Male       47     47.00%
  Female       53     53.00%

Tabulate Positive Integer Vector

Create a frequency table for a vector of positive integers. By default, if a vector x contains only positive integers, then tabulate returns 0 counts for the integers between 1 and max(x) that do not appear in x. To avoid this behavior, convert the vector x to a categorical vector before calling tabulate.

Load the patients data set. Display the first five entries of the Height variable. Each value indicates the height, in inches, of a patient.

load patients
Height(1:5)

ans = 5×1

    71
    69
    64
    67
    64

Create a frequency table that shows, in its second and third columns, the number and percentage of patients in the data set that have a particular height. Display the first five entries and the last five entries of the matrix that tabulate returns. tbl contains one row for each height between 1 and 72 inches, where 72 is the maximum height value in Height.

tbl = tabulate(Height);
first = tbl(1:5,:)

first = 5×3

     1     0     0
     2     0     0
     3     0     0
     4     0     0
     5     0     0

last = tbl(end-4:end,:)

last = 5×3

    68    15    15
    69     8     8
    70    11    11
    71    10    10
    72     4     4

Generate a frequency table that shows Count and Percent values only for heights that appear in the Height variable. Convert Height to a categorical variable, and then call the tabulate function.

newHeight = categorical(Height);
tabulate(newHeight)

  Value    Count   Percent
     60        1      1.00%
     62        3      3.00%
     63        7      7.00%
     64       12     12.00%
     65        8      8.00%
     66       15     15.00%
     67        6      6.00%
     68       15     15.00%
     69        8      8.00%
     70       11     11.00%
     71       10     10.00%
     72        4      4.00%

Create Table Array from Tabulated Data

Create a frequency table from a character array by using tabulate. Convert the resulting cell array to a table array, and visualize the results.

Load the carsmall data set. Tabulate the data in the Origin variable, which shows the country of origin of each car in the data set. Convert the resulting cell array tbl to a table array t. Change the Value column to a categorical vector.

load carsmall
tbl = tabulate(Origin);
t = cell2table(tbl,'VariableNames', ...
    {'Value','Count','Percent'});
t.Value = categorical(t.Value)

t=6×3 table
     Value     Count    Percent
    _______    _____    _______

    USA         69        69   
    France       4         4   
    Japan       15        15   
    Germany      9         9   
    Sweden       2         2   
    Italy        1         1   

Create a bar graph from the frequency table.

bar(t.Value,t.Count)
xlabel('Country of Origin')
ylabel('Number of Cars')

Tabulate Data with Missing Values

Create a frequency table from a numeric vector with NaN values.

Load the carsmall data set. The MPG variable contains the miles per gallon measurement of 100 cars. For six of the cars, the MPG value is missing (NaN).

load carsmall
numcars = length(MPG)

numcars = 100

nanindex = isnan(MPG);
numMissingMPG = length(MPG(nanindex))

numMissingMPG = 6

Create a frequency table using MPG. Convert the matrix output from tabulate to a table, and label the table columns.

tbl = tabulate(MPG);
t = array2table(tbl,'VariableNames', ...
    {'Value','Count','Percent'})

t=37×3 table
    Value    Count    Percent
    _____    _____    _______

       9       1      1.0638 
      10       2      2.1277 
      11       1      1.0638 
      13       4      4.2553 
      14       5      5.3191 
    14.5       1      1.0638 
      15       5      5.3191 
    15.5       1      1.0638 
      16       2      2.1277 
    16.5       2      2.1277 
      17       1      1.0638 
    17.5       2      2.1277 
      18       4      4.2553 
    18.5       1      1.0638 
      19       2      2.1277 
      20       2      2.1277 
      ⋮

The frequency table displays data only for the 94 cars with numeric MPG values. tabulate calculates the percentage of each MPG value in this subset of cars, not the entire set of 100 cars.

tnumcars = sum(t.Count)

tnumcars = 94

Input Arguments

x — Input data

numeric vector | logical vector | categorical vector | character array | string array | cell array of character vectors

Input data, specified as a numeric vector, logical vector, categorical vector, character array, string array, or cell array of character vectors.

• If x is a numeric vector, then tbl is a numeric matrix.

• If x is a logical vector, categorical vector, character array, string array, or cell array of character vectors, then tbl is a cell array.

Note

If the elements of x are positive integers, then the frequency table includes 0 counts for the integers between 1 and max(x) that do not appear in x. For an example, see Tabulate Positive Integer Vector.

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

Output Arguments

tbl — Frequency table

numeric matrix | cell array

Frequency table, returned as a numeric matrix or cell array. tbl includes the following information.

Column	Description
1st column (Value)	Unique values of x
2nd column (Count)	Number of instances of each value
3rd column (Percent)	Percentage of each value

Extended Capabilities

Tall Arrays

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

This function fully supports tall arrays. For more information, see Tall Arrays (MATLAB).