To create a visualization of **3-Dimensional plots** in **2-Dimensional space** we use contour plots in Matplotlib. Contour plots are also known as** Level Plots**.

- Suppose there are
**two variables X and Y**and you want**to plot them**then the response of**two variables**will be**Z**and it will be plotted as slices on the**X-Y plane**due to**which contours**are also referred to as**Z-slices**or**iso-response**. - We should use
**contour plot**if you want to see how the value of**Z**changes as a function of two inputs that is**X and Y**, like this**Z = f(X,Y)**. - A
**contour line**or**isoline of a function**of two variables is**basically a curve along**which the**function has a constant value**. - There are two functions in Matplotlib that is
`contour()`

(this is used**to draw the contour lines**) and`contourf()`

(this is used**to draw filled contours**).

### Uses of Contour Plot:

There are some uses of contour plot given below:

- To
**visualize density**. - To visualize the
**meteorological department**. - To visualize
**the heights of mountains**.

## Matplotlib `contour()`

Function

The function `matplotlib.pyplot.contour()`

is useful when **Z = f(X, Y)** here, **Z** changes as a function of input **X and Y**.

A `contourf()`

function is also available in matplotlib which **allows us to draw filled contours.**

This method returns a** QuadContourSet.** The required **syntax** for the same is given below:

` matplotlib.pyplot.contour([X, Y, ] Z, [levels], **kwargs)`

Let us discuss the parameters of this function:

**1. X, Y**

This parameter indicates **2-D NumPy arrays** with having same shape as Z or same like 1-D arrays in a manner such that `len(X)==M`

and `len(Y)==N`

(where M are rows and N are columns of Z)

**2. Z**

This parameter indicates the height values over which the contour is drawn. The shape is (M, N).

**3. levels**

This parameter is used to determine the number and position of the contour lines.

Let us cover some Examples of this function.

## Simple Contour Lines Example:

In this example we will plot contour lines with the help of `contour()`

function:

Let’s take another example for contour plot.

## Filled Contour Plot Example:

Now let us draw a filled contour with the help of `contourf()`

function: