线#

初始化线类#

使用以下构造函数创建线跟踪器：

Line(port)

此构造函数使用一个参数：

范围

描述

port

线路跟踪器连接到的 3 线端口，无论它是 大脑 上的端口，还是 3 线扩展器 上的端口。

必须先创建 Brain 或 3-Wire Expander，然后才能使用 Line Class 构造函数创建对象。

# Create the Brain.
brain = Brain()
# Construct a Line Tracker "line" with the Line class.
line = Line(brain.three_wire_port.a)

This line object will be used in all subsequent examples throughout this API documentation when referring to Line class methods.

类方法#

reflectivity()#

The reflectivity(units) method returns the reflectivity measured by the Line Tracker. The reflectivity of the Line Tracker is an estimation based on the raw value of the sensor. A reflectivity of 0% is a raw value of 3000 or greater. A reflectivity of 100% is a raw value of 0.

参数

描述

单位

Optional. The only valid unit for reflectivity is PERCENT.

**返回：**线跟踪器测量的反射率，范围为 0 - 100%。

# Print the reflectivity of the Line Tracker to the
# Brain's screen.
brain.screen.print(line.reflectivity())

changed()#

The changed(callback, arg) method registers a callback function for when the value of the Line Tracker changes.

参数

描述

打回来

当线跟踪器的值改变时调用的回调函数。

arg

**可选。**传递给回调函数的参数元组。

**返回：**无。

# Define a function line_changed().
def line_changed():
    # The Brain will print that the value detected by the
    # Line Tracker changed on the Brain's screen.
    brain.screen.print("Line Tracker changed")	
# Run line_changed when the value of the Line Tracker changes.
line.changed(line_changed)
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