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xline

Vertical line with constant x-value

Description

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xline(x) creates a vertical line at one or more x-coordinates in the current axes. For example, xline(2) creates a line at x=2.

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xline(x,LineSpec) specifies the line style, the line color, or both. For example, xline([12 20 33],'--b') creates three dashed blue lines.

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xline(x,LineSpec,labels) adds labels to the lines.

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xline(___,Name,Value) specifies constant line properties using one or more name-value pair arguments. For a list of properties, see ConstantLine Properties. Specify name-value pairs after all other input arguments.

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xline(ax,___) creates the lines in the specified axes instead of the current axes.

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xl = xline(___) returns a ConstantLine object or an array of ConstantLine objects. Use xl to modify or query properties of the line after it is created.

Examples

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Create a vertical line at x = 3.

xline(3);

Figure contains an axes object. The axes object contains an object of type constantline.

To create a line with a label, you must also specify the line style. The default line style is a solid line, '-'.

x = linspace(0,6,100);
y = exp(x);
plot(x,y)
xline(4.5,'-',{'Acceptable','Limit'});

Figure contains an axes object. The axes object contains 2 objects of type line, constantline.

Create a vector of normally distributed random numbers and display them in a histogram. Then create three vertical lines with labels at the average value, one standard deviation below the average, and one standard deviation above the average.

data = 5 * randn(1,500) + 20;
histogram(data,'FaceAlpha',0.1,'EdgeAlpha',0.1);
m = mean(data);
s = std(data);
xline([m-s m m+s],'-',{'-1 Standard Dev.','Average','+1 Standard Dev.'})

Figure contains an axes object. The axes object contains 4 objects of type histogram, constantline.

Create a red dashed line at x = 5.

xline(5,'--r');

Figure contains an axes object. The axes object contains an object of type constantline.

Create a vertical dash-dot line with both a label and a display name for a legend.

y = [3187 2693 1771 1826 1958 3222 1645];
barh(y,'DisplayName','Daily Sales')
xl = xline(2328,'-.','Average','DisplayName','Average Sales');

Figure contains an axes object. The axes object contains 2 objects of type bar, constantline. These objects represent Daily Sales, Average Sales.

Adjust the vertical and horizontal alignment of the label, then display the legend.

xl.LabelVerticalAlignment = 'middle';
xl.LabelHorizontalAlignment = 'center';
legend('show');

Figure contains an axes object. The axes object contains 2 objects of type bar, constantline. These objects represent Daily Sales, Average Sales.

Call the tiledlayout function to create a 2-by-1 tiled chart layout. Call the nexttile function to create the axes objects ax1 and ax2. Then plot into each of the axes. Add a dotted vertical line and label to each plot by passing the axes to the xline function.

tiledlayout(2,1)
ax1 =nexttile;
x = linspace(0,10,200);
y1 = cos(x); 
plot(ax1,x,y1)

ax2 = nexttile;
y2 = sin(x); 
plot(ax2,x,y2)

xline(ax1,pi/2,':','cos(\pi/2)=0');
xline(ax2,pi,':','sin(\pi)=0');

Figure contains 2 axes objects. Axes object 1 contains 2 objects of type line, constantline. Axes object 2 contains 2 objects of type line, constantline.

Input Arguments

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x-coordinates, specified as a scalar or a vector containing numeric, categorical, datetime, or duration values. The data type of x must match the data type of the x-axis.

Example: xline(10) displays a line at x=10.

Example: xline([13 20 33]) displays lines at x=13, x=20, and x=33.

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

Line style and color, specified as a character vector or string scalar containing characters and symbols. The characters and symbols can appear in any order. You can specify the line style, line color, or both. Marker symbols such as 'o' are ignored.

Example: '--g' is a green dashed line.

Line StyleDescriptionResulting Line
'-'Solid line

Sample of solid line

'--'Dashed line

Sample of dashed line

':'Dotted line

Sample of dotted line

'-.'Dash-dotted line

Sample of dash-dotted line, with alternating dashes and dots

Color NameShort NameAppearance
'red''r'

Sample of the color red

'green''g'

Sample of the color green

'blue''b'

Sample of the color blue

'cyan' 'c'

Sample of the color cyan

'magenta''m'

Sample of the color magenta

'yellow''y'

Sample of the color yellow

'black''k'

Sample of the color black

'white''w'

Sample of the color white

Target axes, specified as an Axes object. Use this argument if you want xline to plot in axes other than the current axes.

Line labels, specified as a character vector, string scalar, cell array of character vectors, or string array.

Create a Label for One Line

Specify a character vector or a string scalar to display one line of text. To display multiple lines of text, specify a cell array of character vectors or a string array.

PresentationHow to Specify labelsExample
One line of textSpecify a character vector or a string scalar.

xline(12,'-','Sample')

A vertical line in an axes with a label.

Multiline textSpecify a cell array of character vectors or a string array. Each element in the array is a different line of text.
xline(12,'-',{'Sample','x=12'})

A vertical line in an axes with a label that has two lines of text.

Create Labels for Multiple Lines

Specify a character vector or a string scalar to display the same label next to all the lines. Specify a cell array of character vectors or a string array to display different labels for each line.

PresentationHow to Specify labelsExample
One shared text labelSpecify a character vector or a string scalar.

xline([13 20 33],'-','Sample')

Three vertical lines in an axes with matching labels.

Different labels for each lineSpecify a cell array of character vectors or a string array. Each element in the array is a label for a different line. The number of elements in the labels array must match the length of x.
label = {'Sample 1','Sample 2','Sample 3'};
xline([13 20 33],'-',label)

Three vertical lines in an axes with different labels.

Different labels with some multiline labelsCreate a cell array of character vectors or a string array. Use the sprintf function to insert newline characters ('\n') in the text.
label = {'Sample 1',sprintf('Sample 2\nx=20'),'Sample 3'};
xline([13 20 33],'-',label)

Three vertical lines in an axes with different labels. The label for the second line has two lines of text.

Name-Value Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: xline(5,'LabelVerticalAlignment','middle') specifies the vertical alignment of the label as 'middle'.

Note

The properties listed here are only a subset. For a complete list, see ConstantLine Properties.

Line color, specified as an RGB triplet, a hexadecimal color code, a color name, or a short name.

For a custom color, specify an RGB triplet or a hexadecimal color code.

  • An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1]; for example, [0.4 0.6 0.7].

  • A hexadecimal color code is a character vector or a string scalar that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Thus, the color codes '#FF8800', '#ff8800', '#F80', and '#f80' are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
'red''r'[1 0 0]'#FF0000'

Sample of the color red

'green''g'[0 1 0]'#00FF00'

Sample of the color green

'blue''b'[0 0 1]'#0000FF'

Sample of the color blue

'cyan' 'c'[0 1 1]'#00FFFF'

Sample of the color cyan

'magenta''m'[1 0 1]'#FF00FF'

Sample of the color magenta

'yellow''y'[1 1 0]'#FFFF00'

Sample of the color yellow

'black''k'[0 0 0]'#000000'

Sample of the color black

'white''w'[1 1 1]'#FFFFFF'

Sample of the color white

'none'Not applicableNot applicableNot applicableNo color

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB® uses in many types of plots.

RGB TripletHexadecimal Color CodeAppearance
[0 0.4470 0.7410]'#0072BD'

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue

[0.8500 0.3250 0.0980]'#D95319'

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange

[0.9290 0.6940 0.1250]'#EDB120'

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow

[0.4940 0.1840 0.5560]'#7E2F8E'

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple

[0.4660 0.6740 0.1880]'#77AC30'

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green

[0.3010 0.7450 0.9330]'#4DBEEE'

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue

[0.6350 0.0780 0.1840]'#A2142F'

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Example: 'g'

Example: [0.6 0.2 0.5]

Example: '#D2F9A7'

Line width, specified as a positive value in points.

Legend label, specified as a character vector or string scalar. The legend does not display until you call the legend command. If you do not specify the text, then legend sets the label using the form 'dataN'.

Horizontal alignment of the label with respect to the line, specified as one of the options in the table.

OptionDescriptionExample
'right'Right side of the line.

'left'Left side of the line.

'center'Center of the line. The label segments the line.

Vertical alignment of the label with respect to the line, specified as one of the options in the table.

OptionDescriptionExample
'top'Top of the line

'middle'Middle of the line

'bottom'Bottom of the line

Label orientation, specified as 'aligned' or 'horizontal'. Examples are shown in the table.

OrientationDescriptionExample
'aligned'Label has the same orientation as the line.

'horizontal'Label is horizontal, regardless of the line orientation.

Algorithms

In a 3-D view of the axes, the constant line appears in the x-y plane at the midpoint of the z-axis limits. If the axes are rotated, then the constant line rotates accordingly.

See Also

Functions

Properties

Introduced in R2018b