contourf
Filled 2D contour plot
Syntax
Description
contourf(
creates a filled contour plot
containing the isolines of matrix Z
)Z
, where Z
contains height values on the xy plane. MATLAB^{®} automatically selects the contour lines to display. The column and row indices
of Z
are the x and y coordinates
in the plane, respectively.
contourf(___,
specifies the
contour lines to display as the last argument in any of the previous syntaxes. Specify
levels
)levels
as a scalar value n
to display the contour
lines at n
automatically chosen levels (heights). To draw the contour
lines at specific heights, specify levels
as a vector of monotonically
increasing values. To draw the contours at one height (k
), specify
levels
as a twoelement row vector [k k]
.
contourf(___,
specifies
additional options for the contour plot using one or more namevalue pair arguments. Specify
the options after all other input arguments. For a list of properties, see Contour Properties.Name,Value
)
contourf(
displays the
contour plot in the target axes. Specify the axes as the first argument in any of the
previous syntaxes.ax
,___)
returns the
contour matrix M
= contourf(___)M
, which contains the (x,
y) coordinates of the vertices at each level.
Examples
Contours of Peaks Function
Define Z
as a function of two variables. In this case, call the peaks
function to create Z
. Then display a filled contour plot of Z
, letting MATLAB® choose the contour levels.
Z = peaks; contourf(Z)
Contours at Ten Levels
Define Z
as a function of two variables, X
and Y
. Then display contours at 10 levels of Z
.
x = linspace(2*pi,2*pi); y = linspace(0,4*pi); [X,Y] = meshgrid(x,y); Z = sin(X) + cos(Y); contourf(X,Y,Z,10)
Contours at Specific Levels with Labels
Define Z
as a function of X
and Y
. In this case, call the peaks
function to create X
, Y
, and Z
. Then display contours at levels 2
and 3
.
The white region corresponds to the heights less than 2
. The purple region corresponds to heights between 2
and 3
. And the yellow region corresponds to heights that are greater than 3
.
[X,Y,Z] = peaks(50); contourf(X,Y,Z,[2 3],'ShowText','on')
Contours at One Level
Define Z
as a function of X
and Y
. In this case, call the peaks
function to create X
, Y
, and Z
. Then display contours at Z = 2
.
[X,Y,Z] = peaks; contourf(X,Y,Z,[2 2])
Dashed Contour Lines
Create a contour plot, and specify the dashed line style.
[X,Y,Z] = peaks;
contourf(X,Y,Z,'')
Custom Line Width
Create a filled contour plot. Make the contour lines thicker by setting the LineWidth
property to 3
.
Z = peaks; [M,c] = contourf(Z); c.LineWidth = 3;
Contours Over Discontinuous Surface
Insert NaN
values wherever there are discontinuities on a surface. The contourf
function does not draw contour lines in those regions.
Define matrix Z
as a sampling of the peaks
function. Replace all values in column 26
with NaN
values. Then plot the contours of the modified Z
matrix.
Z = peaks; Z(:,26) = NaN; contourf(Z)
Input Arguments
X
— xcoordinates
matrix  vector
xcoordinates, specified as a matrix the same size as
Z
, or as a vector with length n
, where
[m,n] = size(Z)
. The default value of X
is the
vector (1:n)
.
When X
is a matrix, the values must be strictly increasing or
decreasing along one dimension and remain constant along the other dimension. The
dimension that varies must be the opposite of the dimension that varies in
Y
. You can use the meshgrid
function to create X
and
Y
matrices.
When X
is a vector, the values must be strictly increasing or
decreasing.
Example: X = 1:10
Example: X = [1 2 3; 1 2 3; 1 2 3]
Example: [X,Y] = meshgrid(1:10)
The XData
property of the Contour
object
stores the xcoordinates.
Data Types: single
 double
 int8
 int16
 int32
 int64
 uint8
 uint16
 uint32
 uint64
Y
— ycoordinates
matrix  vector
ycoordinates, specified as a matrix the same size as
Z
, or as a vector with length m
, where
[m,n] = size(Z)
. The default value of Y
is the
vector (1:m)
.
When Y
is a matrix, the values must be strictly increasing or
decreasing along one dimension and remain constant along the other dimension. The
dimension that varies must be the opposite of the dimension that varies in
X
. You can use the meshgrid
function to create the X
and
Y
matrices.
When Y
is a vector, the values must be strictly increasing or
decreasing.
Example: Y = 1:10
Example: Y = [1 1 1; 2 2 2; 3 3 3]
Example: [X,Y] = meshgrid(1:10)
The YData
property of the Contour
object
stores the ycoordinates.
Data Types: single
 double
 int8
 int16
 int32
 int64
 uint8
 uint16
 uint32
 uint64
Z
— zcoordinates
matrix
zcoordinates, specified as a matrix. This matrix must have at least two rows and two columns, and it must contain at least two different values.
Example: Z = peaks(20)
The ZData
property of the Contour
object
stores the zcoordinates.
Data Types: single
 double
 int8
 int16
 int32
 int64
 uint8
 uint16
 uint32
 uint64
levels
— Levels
scalar  vector
Contour levels, specified as a scalar whole number or a vector. Use this argument to
control the number and location of the contour lines. When you do not specify the
levels, the contourf
function chooses the levels automatically.
To draw contour lines at n automatically chosen heights, specify
levels
as the scalar value n.To draw the contour lines at specific heights, specify
levels
as a vector of monotonically increasing values.To draw contour lines at a single height
k
, specifylevels
as a twoelement row vector[k k]
.
The contourf
function uses the current colormap to fill the
spaces between the levels in the plot. The first color fills the space between the
lowest level and the level above it. The last color corresponds to
Z
values that are greater than the highest level in the plot. If
Z
contains values that are smaller than the lowest level
displayed in the plot, the region between the lowest level and the smallest
Z
value is white.
Example: contourf(peaks,10)
draws contour lines at 10
automatically chosen heights on the peaks
function.
Example: contourf(peaks,[4 0 4])
draws contour lines at 3
specific heights on the peaks
function: 4
,
0
, and 4
.
Example: contourf(peaks,[3 3])
draws contour lines to show where
the height of the peaks
function is
3
.
Data Types: single
 double
 int8
 int16
 int32
 int64
 uint8
 uint16
 uint32
 uint64
LineSpec
— Line style and color
character vector  string scalar
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 Style  Description  Resulting Line 

''  Solid line 

''  Dashed line 

':'  Dotted line 

'.'  Dashdotted line 

Color Name  Short Name  Appearance 

'red'  'r' 

'green'  'g' 

'blue'  'b' 

'cyan'
 'c' 

'magenta'  'm' 

'yellow'  'y' 

'black'  'k' 

'white'  'w' 

ax
— Target axes
Axes
object
Target axes, specified as an Axes
object. If you do not specify
the axes, then contourf
plots into the current axes.
NameValue Arguments
Specify optional
commaseparated 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
.
contourf(Z,'ShowText','on')
displays the contour line
labels.Note
The properties listed here are only a subset. For a complete list, see Contour Properties.
ShowText
— Contour line labels
'off'
(default)  on/off logical value
Contour line labels, specified as 'on'
or 'off'
,
or as numeric or logical 1
(true
) or
0
(false
). A value of 'on'
is equivalent to true
, and 'off'
is equivalent to
false
. Thus, you can use the value of this property as a logical
value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState
.
'on'
— Display the height values along the contour lines.'off'
— Do not label the contour lines.
LineWidth
— Line Width
0.5
(default)  positive value
Contour line width, specified as a positive value in points. One point equals 1/72 inch.
LabelSpacing
— Label spacing
144
(default)  scalar
Label spacing along the contour lines, specified as a scalar value in points, where one point is 1/72 inch. Use this property to control the number of contour labels along the contour lines. Smaller values produce more labels.
You must set the ShowText
property to 'on'
for
the LabelSpacing
property to have an effect.
If you use the clabel
function to display the labels,
then the LabelSpacing
property has no effect and the plot displays
one label per line.
Output Arguments
M
— Contour matrix
matrix
Contour matrix, returned as tworow matrix. This matrix contains the contour levels (heights) and the coordinates of the vertices at each level. The data is arranged sequentially in n sets of columns for n contour lines:
The first column in each set contains the contour level and the number of vertices at that level. The top number is the contour level, and the bottom number is the number of vertices.
Subsequent columns in the set are the (x, y) coordinates of the vertices. Each column represents an ordered pair. The top number is the xcoordinate, and the bottom number is the ycoordinate.
For example, here are the first few columns of the contour matrix M =
contour(peaks(3))
:
The ContourMatrix
property of the Contour
object stores the contour matrix.
c
— Contour object
Contour
object
Contour
object. Use this object to set properties after
displaying the contour plot.
Extended Capabilities
GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.
Usage notes and limitations:
This function accepts GPU arrays, but does not run on a GPU.
For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).
Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.
Usage notes and limitations:
This function operates on distributed arrays, but executes in the client MATLAB.
For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).
See Also
Functions
Properties
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