# Mastering Matplotlib: Filling in Areas Between Values in Plots

Have you ever wondered how to fill in areas between values on your Matplotlib plot? Whether it’s the area under a curve or between two horizontal or vertical lines, this article will guide you through the process.

With the help of the `fill_between()` and `fill_betweenx()` methods, you can easily add color and emphasis to specific regions of your plot. In this article, we will explore four subtopics in detail, providing you with the necessary steps and primary keywords to help you understand and execute them.

## Filling in areas between values in Matplotlib plot

### 1. Filling in area between two horizontal lines

If you have a plot with horizontal lines for which you want to fill in the area between them, you can use the `fill_between()` method in Matplotlib. Here are the steps:

1. ### Import Matplotlib:

First, you need to import the Matplotlib library to access the `fill_between()` method.

2. ### Create a plot:

Create your plot with x and y values, including the horizontal lines for which you want to fill the area between.

3. ### Determine x and y values:

Assign the x and y values to the `fill_between()` method, specifying the region between the horizontal curves.

4. ### Choose the color:

Choose the color you want to fill in the area between the horizontal lines.

By following these steps, you can fill the area between two horizontal lines on your Matplotlib plot.

The primary keywords for this subtopic include `fill_between()`, horizontal curves, x values, and y values.

### 2. Filling in area under a curve

To fill the area under a curve, you first need to plot the curve. In Matplotlib, you can use the `fill_between()` method to color the area beneath the curve.

1. ### Create a plot:

Create a plot with x and y values, including the curve you want to fill the area under.

2. ### Determine x and y values:

Assign the x and y values to the `fill_between()` method, specifying the area under the curve.

3. ### Choose the color:

Choose the color you want to fill the area under the curve.

By following these steps, you can fill the area under a curve on your Matplotlib plot. The primary keywords for this subtopic include `fill_between()`, under a curve, x values, and y values.

### 3. Filling in area above a curve

Similar to filling in the area under a curve, you can also fill in the area above a curve using the `fill_between()` method.

1. ### Create a plot:

Create a plot with x and y values, including the curve you want to fill the area above.

2. ### Determine x and y values:

Assign the x and y values to the `fill_between()` method, specifying the area above the curve.

3. ### Choose the color:

Choose the color you want to fill the area above the curve.

By following these steps, you can fill the area above a curve on your Matplotlib plot.

The primary keywords for this subtopic include `fill_between()`, above a curve, x values, and y values.

### 4. Filling in area between two vertical lines

To fill the area between two vertical lines on a Matplotlib plot, you can use the `fill_betweenx()` method.

1. ### Create a plot:

Create your plot with x and y values, including the vertical lines for which you want to fill the area between.

2. ### Determine x and y values:

Assign the x and y values to the `fill_betweenx()` method, specifying the region between the vertical curves.

3. ### Choose the color:

Choose the color you want to fill the area between the vertical lines.

By following these steps, you can fill the area between two vertical lines on your Matplotlib plot.

The primary keywords for this subtopic include `fill_betweenx()`, vertical curves, x values, and y values.

## Conclusion:

In summary, filling in areas between values on a Matplotlib plot is a simple process that can add emphasis and color to specific regions.

With the `fill_between()` and `fill_betweenx()` methods, you can easily fill areas under or above a curve, between horizontal or vertical lines, or any other region you desire. By following the steps provided in this article and using the primary keywords, you can master this technique and create visually appealing plots with clear and defined regions.

In conclusion, filling in areas between values using Matplotlib is a simple yet essential technique for emphasizing regions of interest in a plot. This article has highlighted four subtopics, including filling in areas between two horizontal lines, under and above a curve, and between two vertical lines, with the necessary steps and primary keywords.

By following the provided instructions, readers can use the `fill_between()` and `fill_betweenx()` methods to create visually appealing and informative plots with ease. The importance of this technique cannot be overemphasized, and mastering it is essential for anyone involved in data visualization.

Keep practicing and implementing these techniques to create more impactful and informative plots.