# Line Chart With Two Y Axis Matplotlib

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Line charts are a popular type of visualization used to display data trends over time. They are particularly useful for showing the relationship between two variables. In some cases, it may be necessary to have two y axes on a line chart to compare two different sets of data that have different scales. This is where matplotlib, a popular Python library for data visualization, comes in handy.

## How to create a line chart with two y axes using matplotlib

To create a line chart with two y axes using matplotlib, you will need to follow these steps:

### Step 1: Import the necessary libraries

Before you can start creating your line chart, you will need to import the necessary libraries. In this case, you will need to import the matplotlib library as well as the numpy library, which will be used for data manipulation.

### Step 2: Generate the data

Next, you will need to generate the data that you want to plot on your line chart. This can be done using the numpy library. You can create two separate arrays for the x and y values.

### Step 3: Create the figure and axes

Now, you can create the figure and axes for your line chart using the matplotlib library. You can use the `plt.subplots()` function to create a figure and a set of subplots. The number of subplots will depend on the number of y axes you want to have on your line chart.

### Step 4: Plot the data

Once you have created the figure and axes, you can plot your data on the line chart. You can use the `ax.plot()` function to plot the data on the axes. You will need to specify the x and y values as well as the line style and color.

### Step 5: Set the y axis labels

Since you have two y axes on your line chart, you will need to set the labels for each of them. You can use the `ax.set_ylabel()` function to set the label for each y axis. You can also specify the font size, font weight, and other formatting options for the labels.

### Step 6: Set the y axis limits

Depending on the scales of your data, you may need to set the limits for each y axis. You can use the `ax.set_ylim()` function to set the minimum and maximum values for each y axis. This will ensure that your data fits within the specified limits.

### Step 7: Add a legend

If you have multiple lines on your line chart, you may want to add a legend to identify each line. You can use the `ax.legend()` function to add a legend to your line chart. You can specify the labels for each line as well as the location and formatting options for the legend.

### Step 8: Customize the appearance of the chart

Finally, you can customize the appearance of your line chart using various formatting options. You can use the `ax.set_title()` function to set the title of your chart, the `ax.set_xlabel()` function to set the x axis label, and the `ax.grid()` function to add gridlines to your chart. You can also specify the line styles, colors, and markers for each line.

## Sample “Line chart with two y axis matplotlib”

Here are 5 sample line charts with two y axes created using matplotlib:

### Chart 1: Temperature and rainfall over time

This line chart shows the relationship between temperature and rainfall over time. The temperature values are shown on the left y axis, while the rainfall values are shown on the right y axis.

### Chart 2: Sales and profit over time

This line chart shows the relationship between sales and profit over time. The sales values are shown on the left y axis, while the profit values are shown on the right y axis.

### Chart 3: Stock price and volume over time

This line chart shows the relationship between stock price and volume over time. The stock price values are shown on the left y axis, while the volume values are shown on the right y axis.

### Chart 4: Website traffic and conversions over time

This line chart shows the relationship between website traffic and conversions over time. The website traffic values are shown on the left y axis, while the conversion values are shown on the right y axis.

### Chart 5: Population and GDP over time

This line chart shows the relationship between population and GDP over time. The population values are shown on the left y axis, while the GDP values are shown on the right y axis.

## Frequently Asked Questions (FAQ) about “Line chart with two y axis matplotlib”

1. How do I create a line chart with two y axes using matplotlib?

2. Can I have more than two y axes on a line chart?

3. How do I set the labels for the y axes?

4. How do I set the limits for the y axes?

5. How do I add a legend to my line chart?

6. How do I customize the appearance of my line chart?

7. Can I change the line styles, colors, and markers for each line?

8. How do I add gridlines to my line chart?

9. Can I change the font size and font weight of the y axis labels?

10. How do I save my line chart as an image file?

## Tags:

line chart, two y axis, matplotlib, data visualization, python, numpy, line chart with two y axis, line chart with two y axes, line chart with multiple y axes

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