# 5 Best Ways to Plot 3D Graphs Using Python Matplotlib

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π‘ Problem Formulation: Plotting 3D graphs in Python is an essential skill for data visualization, especially in fields like physics, chemistry, and engineering, where understanding multi-dimensional data is crucial. Given sets of data points, we want to generate a 3D visualization to observe trends, clusters, and patterns that are not apparent in 2D plots. The desired output is an interactive 3D graph that allows rotation and zooming for better analysis.

## Method 1: Basic 3D Scatter Plot

One of the most straightforward ways to create a 3D graph in matplotlib is a scatter plot. A scatter plot in 3D allows for the visualization of data points in three dimensions using dots in space. This method is particularly useful for identifying relationships and distributions of data points in a three-dimensional space.

Here’s an example:

```import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Sample data
x = [1, 2, 3, 4, 5]
y = [5, 6, 2, 3, 13]
z = [2, 3, 3, 3, 5]

ax.scatter(x, y, z)

plt.show()
```

The output is a 3D scatter plot with the data points plotted at the respective (x, y, z) coordinates.

This code snippet initializes a 3D plotting environment using matplotlib’s Axes3D object. It then creates a simple scatter plot with sample (x, y, z) data points and finally displays the plot using `plt.show()`. Itβs a great way to start with 3D plotting due to its simplicity.

## Method 2: 3D Line Plot

To visualize the trajectory or a series of connected points in three-dimensional space, a 3D line plot can be quite effective. It extends the concept of a 2D line graph by adding an additional z-axis, allowing for the representation of data with three variables.

Here’s an example:

```import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Sample data
x = [1, 2, 3, 4, 5]
y = [5, 6, 2, 3, 13]
z = [2, 3, 3, 3, 5]

ax.plot(x, y, z)

plt.show()
```

The output is a 3D line graph connecting the points sequentially in the order they are defined.

The code snippet creates a 3D line plot using the `plot()` method instead of `scatter()`. It connects the series of (x, y, z) data points in order, illustrating the path or trajectory between them. It’s excellent for time series or any sequential data.

## Method 3: 3D Surface Plot

A 3D surface plot shows a functional relationship between three continuous variables by creating a surface in a three-dimensional space. It is useful for understanding topological patterns in the data or visualizing landscapes and other three-dimensional surfaces.

Here’s an example:

```import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import numpy as np

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Create meshgrid
x = np.linspace(-5, 5, 50)
y = np.linspace(-5, 5, 50)
x, y = np.meshgrid(x, y)
z = np.sin(np.sqrt(x**2 + y**2))

# Plot a 3D surface
ax.plot_surface(x, y, z, cmap='viridis')

plt.show()
```

The output is a 3D surface plot visualizing a three-dimensional sine function.

The code creates a 3D surface plot by first generating a meshgrid with `x` and `y` values. It computes `z` by applying a function to `x` and `y`, and then it plots the surface with a gradient color map. This method is perfect for mathematical functions and landscape data.

## Method 4: 3D Contour Plot

To feel the topography or levels of a three-dimensional surface, contour plots are incredibly useful. Representing slices of the surface at specific intervals, 3D contour plots can help in understanding the changes in gradient or value along the surface.

Here’s an example:

```import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import numpy as np

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Sample data
x = np.linspace(-5, 5, 50)
y = np.linspace(-5, 5, 50)
x, y = np.meshgrid(x, y)
z = x**2 - y**2

# Create a 3D contour plot
ax.contour3D(x, y, z, 50, cmap='binary')

plt.show()
```

The output is a 3D contour plot with 50 levels of contours, providing a layered view of the surface.

The code snippet sets up a contour plot in 3D with `contour3D()`. Just like the surface plot, it utilizes a meshgrid to calculate values, but instead of a continuous surface, it shows discrete layers or contours, which are great for visualizing elevation maps and other similar data.

## Bonus One-Liner Method 5: Interactive 3D Scatter Plot with Plotly

For a more interactive experience, Plotly’s interactive plotting capabilities can be used to create 3D scatter plots with functionalities like zooming and rotating. It’s a simple one-liner when using Plotly Express.

Here’s an example:

```import plotly.express as px

fig = px.scatter_3d(x=[1, 2, 3, 4, 5], y=[10, 11, 12, 13, 14], z=[101, 102, 103, 104, 105])
fig.show()
```

The output is an interactive 3D scatter plot that you can manipulate in the browser.

This code uses Plotly Express to create an interactive 3D scatter plot, taking arrays of `x`, `y`, and `z` as its arguments. The resulting plot is rendered in a web browser, offering a high degree of interactivity. It’s an excellent choice for presentations and exploratory data analysis.

## Summary/Discussion

• Method 1: Basic 3D Scatter Plot. Simple and direct method for plotting 3D points. Not suitable for depicting relationships between points.
• Method 2: 3D Line Plot. Great for showing relationships and trends between points, but can be confusing if too many lines overlap.
• Method 3: 3D Surface Plot. Effective at showing landscapes and functions. Can be complicated to set up the meshgrid for complex surfaces.
• Method 4: 3D Contour Plot. Useful for understanding gradients and levels. Can be less intuitive than surface plots for some data sets.
• Method 5: Interactive 3D Scatter Plot with Plotly. Offers a high degree of interactivity, very engaging, but requires an external library and browser support.