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standardizeMissing

Insert standard missing-value indicators

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Syntax

  • B = standardizeMissing(A,indicator)
    example
  • B = standardizeMissing(A,indicator,'DataVariables',vars)
    example

Description

example

B = standardizeMissing(A,indicator) replaces values specified in indicator with standard missing-value indicators in an array or table.

Standard missing-value indicators depend on the data type:

  • NaN for double, single, duration, and calendarDuration

  • NaT for datetime

  • <missing> for string

  • <undefined> for categorical

  • ' ' for char

  • {''} for cell of character arrays

example

B = standardizeMissing(A,indicator,'DataVariables',vars) replaces values only in the table variables specified by vars.

Examples

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Open Script

Create a row vector and replace all instances of -99 with the standard missing value for double data types, NaN.

A = [0 1 5 -99 8 3 4 -99 16];
B = standardizeMissing(A,-99)

B =

     0     1     5   NaN     8     3     4   NaN    16
Open Script

Create a table containing Inf and 'N/A' to represent missing values.

dblVar = [NaN;3;Inf;7;9];
cellstrVar = {'one';'three';'';'N/A';'nine'};
charVar = ['A';'C';'E';' ';'I'];
categoryVar = categorical({'red';'yellow';'blue';'violet';''});

A = table(dblVar,cellstrVar,charVar,categoryVar)

A = 

    dblVar    cellstrVar    charVar    categoryVar
    ______    __________    _______    ___________

    NaN       'one'         A          red        
      3       'three'       C          yellow     
    Inf       ''            E          blue       
      7       'N/A'                    violet     
      9       'nine'        I          <undefined>

Replace all instances of Inf with NaN and replace all instances of 'N/A' with the empty character vector, ''.

B = standardizeMissing(A,{Inf,'N/A'})

B = 

    dblVar    cellstrVar    charVar    categoryVar
    ______    __________    _______    ___________

    NaN       'one'         A          red        
      3       'three'       C          yellow     
    NaN       ''            E          blue       
      7       ''                       violet     
      9       'nine'        I          <undefined>
Open Script

Replace instances of Inf and 'N/A' occurring in specified variables of a table with the standard missing value indicators.

Create a table containing Inf and 'N/A' to represent missing values.

a = {'alpha';'bravo';'charlie';'';'N/A'};
x = [1;NaN;3;Inf;5];
y = [57;732;93;1398;Inf];

A = table(a,x,y)

A = 

        a         x      y  
    _________    ___    ____

    'alpha'        1      57
    'bravo'      NaN     732
    'charlie'      3      93
    ''           Inf    1398
    'N/A'          5     Inf

For the variables a and x, replace instances of Inf with NaN and 'N/A' with the empty character vector, ''.

B = standardizeMissing(A,{Inf,'N/A'},'DataVariables',{'a','x'})

B = 

        a         x      y  
    _________    ___    ____

    'alpha'        1      57
    'bravo'      NaN     732
    'charlie'      3      93
    ''           NaN    1398
    ''             5     Inf

Inf in the variable y remains unchanged because y is not included in the 'DataVariables' name-value pair argument.

Input Arguments

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Input data, specified as a vector, matrix, multidimensional array, table, or timetable. If A is a timetable, then ismissing operates on the table data only and ignores NaT and NaN values in the vector of row times.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | cell | table | timetable | categorical | datetime | duration | calendarDuration

Nonstandard missing-value indicators, specified as a vector or cell array. The elements of indicator define the values that standardizeMissing treats as missing. If A is an array, then indicator must be a vector. If A is a table, then indicator can also be a cell array with entries of multiple data types.

The data types specified in indicator match data types in the corresponding entries of A. The following are additional data type matches between the elements of indicator and elements of A:

  • double indicators match double, single, integer, and logical entries of A.

  • string and char indicators match categorical entries of A.

Example: B = standardizeMissing(A,'N/A') replaces the character vector 'N/A' with the empty character vector, ''.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | cell | datetime | duration

Table variables to standardize, specified as a variable name, a cell array of variable names, a numeric vector, a logical vector, or a function handle. vars can be one of the following:

  • A character vector specifying a single table variable name

  • A cell array of character vectors where each element is a table variable name

  • A vector of table variable indices

  • A logical vector whose elements each correspond to a table variable, where true includes the corresponding variable and false excludes it

  • A function handle that returns a logical scalar, such as @isnumeric

Example: 'Age'

Example: {'Height','Weight'}

Example: @iscategorical

Data Types: char | cell | single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | function_handle

Output Arguments

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Standardized array or table, specified as a vector, matrix, multidimensional array, table, or timetable. B has the same size as A.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | cell | table | timetable | categorical | datetime | duration | calendarDuration

More About

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Tall Array Support

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

Algorithms

standardizeMissing treats leading and trailing white space differently for cell arrays of character vectors, character arrays, and categorical arrays.

  • For cell arrays of character vectors, standardizeMissing does not ignore white space. All character vectors must match exactly a character vector specified in indicator.

  • For character arrays, standardizeMissing ignores trailing white space.

  • For categorical arrays, standardizeMissing ignores leading and trailing white space.

See Also

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Introduced in R2013b

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