Text Formatting in MATLAB

In the real-world data can be any form. This data may be in binary, numeric, text, array, and so on. And this data can be converted into text. In Matlab, the text can be formatted using a formatting operator along with formatting functions such as sprintf, numstr, fprintf, compose. These functions/operators control the text notation, significant digit, text alignment, and so on. 

In this article, we will see, how you can format the text in MATLAB.

A formatting operator has six criteria that include a numeric identifier, flags, field width, precision, subtype, and a conversion character.  In the figure there is space between the operator but while writing code, make sure there are no space characters allowed in the operator. Out of the six field conversion character is only the required field which means it cannot be ignored while formatting text in Matlab. And this conversion character must start by a % percent sign.

Fields of Formatting Operator:

Conversion Character: Just like C programming, Matlab requires a format specifier so that it specifies the notation of the output. The format specifier and meaning is given below:

S.No.	Format Specifier	Meaning
1.	c	Single character(char)
2.	d	Decimal notation (signed)
3.	u	Decimal notation (unsigned).
4.	e	Exponential notation (using a lowercase e, as in 3.1415e+00).
5.	E	Exponential notation (using an uppercase E, as in 3.1415E+00).
6.	f	Fixed-point notation
7.	x	Hexadecimal notation (unsigned, using lowercase letters a–f).
8.	g	The more compact of %e or %f
9.	G	Similar to %g
10.	o	Octal notation (unsigned).
11.	s	String array

Example 1:

Matlab

% MATLAB program for sprintf()
A = 57*ones(1,5);
txt = sprintf('%d %f %o %X %u', A)

Output:

txt = 57 57.00000 71 39 57

Subtype: Before the conversion character, the subtype is the field is represented by a single alphabetic character. It mainly has two types:

S.No.	Subtype specifier	Description
1.	t	The input data are single-precision floating-point values rather than unsigned integers.
2.	b	The input data are double-precision floating-point values rather than unsigned integers.

Example 2:

Matlab

% MATLAB code for subtype
subtype_ = 19;
final_sub = sprintf('%tu',subtype_)

Output:

final_sub = 1100480512

Precision: The next field of formatting operators is a precision field. It is usually denoted with dot notation, it is a nonnegative integer that immediately follows a period.

Example 3:

Matlab

% MATLAB code for check Precision
check_decimal = sprintf('%g   %.2g   %f   %.2f', [1 2 3 4])

Output:

check_decimal = 1 2 3.000000 4.00

We took two g and 2 f format specifiers and can see what a Precision does to the decimal point. 

Field Width: A Field Width is a non-negative integer that specifies the number of digits or characters in the output. Specify different field widths. To show the width for each output, use the | character. For example, in the operator %5.1f, the field width is 5 and 0.1 precision.

Example 4:

Matlab

% MATLAB code for check Field Width
text = sprintf('|%e|%6e|%f|%12f|',[0.455312 12345 2223 0.111123])

Output:

text = '|4.553120e-01|1.2345e+04|2223000000|      0.111123|'

Flags: The flags field is optional. If used then it mainly controls the formatting of the output. Additionally, it is used to describe padding, text alignment, and spacing.

S.No.	Char	Meaning	Example
1.	–	Left-justify the output text	%-7.4d
2.	+	Right-justify the output text	%+7.4d
3.	0	Zero Padding	%06.3f
4.	#	Numeric conversions: For %o, %x, or %X, print 0, 0x, or 0X prefix. For %f, %e, or %E, a print decimal point even when precision is 0. For %g or %G, do not remove trailing zeroes or decimal points.	%#4.0f
5.	Space	Insert a space before the value.	% 4.2f

Identifier: Identifiers are declared after the % and before the $ special characters. It is an integer value to produce the output in a specified order. sprintf by default prints in sequential order, using Identifier we can arrange output in the custom order.

Example 5:

Matlab

% MATLAB code for identifier
sprintf('%3$s %2$s %1$s',...
        'Geeks','Premier','League')

Output:

ans = 'League Premier Geeks'

Formatting Text With compose():

The compose function is used to format the array data into multiple strings. 

Syntax:

var_name = compose(format_specifier,var_name)
str = compose(format_specifier,A,b,...,N)

Example: 

Matlab

% MATLAB code for compose()
compose_str1 = compose("%.5f",45.566)
compose_str2 = compose("%.1f",45.566)

Output:

"compose_str1 = 45.56600"
"compose_str1 = 45.6"

Formatting Text With num2str():

The num2str function is used to format the number into a character array.

Syntax:

new_var = num2str(int_var)
new_var = num2str(int_var,precision)
new_var = num2str(int_var,format_specifier)

Example:

Matlab

% MATLAB code for num2str()
num = 92;
chr = num2str(num)

Output:

chr = '92'