add label to x axis matplotlib code example

Example 1: set axis labels python

# Basic syntax:
plt.xlabel("X axis label") # Add ", fontsize = #" to control fontsize
plt.ylabel("Y axis label")

# Example usage:
plt.plot(range(5))
plt.xlabel("X axis label")
plt.ylabel("Y axis label")
plt.title("Figure title", fontsize = 20)

# Note, xlabel and ylabel come from matplotlib.pyplot and plt is an 
# 	abbreviation for this, e.g. import matplotlib.pyplot as plt

Example 2: adding label to navigation bar

if let navigationBar = self.navigationController?.navigationBar {
    let firstFrame = CGRect(x: 0, y: 0, width: navigationBar.frame.width/2, height: navigationBar.frame.height)
    let secondFrame = CGRect(x: navigationBar.frame.width/2, y: 0, width: navigationBar.frame.width/2, height: navigationBar.frame.height)

    let firstLabel = UILabel(frame: firstFrame)
    firstLabel.text = "First"

    let secondLabel = UILabel(frame: secondFrame)
    secondLabel.text = "Second"

    navigationBar.addSubview(firstLabel)
    navigationBar.addSubview(secondLabel)
}