Question

考虑一下这个颜色解析器的玩具示例。它解析用户输入的颜色，然后描述该颜色。对于此玩具示例，描述颜色意味着仅返回字符串。无论如何，这仅适用于一种颜色，但不适用于多种颜色。

class Colorparser():

  def describe_color(self, val):
    """Describe a color """
    color = parse_color(val)
    desc = "A description" # The real script does some crazy stuff here ;)
    return desc

  def describe_palette(self, vals):
    """Describe colors in palette"""
    descs = [describe_color(v) for v in vals]
    return descs

  def parse_color(self, val):
    """Returns an RGB tupple if color is RGB,
    and converts a hex color to RGB otherwise """

    if type(val) == str:
      color = hex_to_rgb(val)
    elif type(val) == list:
      color = val
    return color

  def hex_to_rgb(self, color):
    """Convertes a hex color to rgb"""
    value = color.lstrip('#')
    lv = len(value)
    return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))

现在这是我的程序：

c = Colorparser()

color = "#F7F7F7"
colors = ["#F7F7F7", "#F7F7F7"]

c.describe_color(color) # works
c.describe_palette(colors) # does not work

我得到了错误：

 NameError                                 Traceback (most recent call last)
<ipython-input-77-4264da0e7d08> in <module>()
     40
     41 c.describe_color(color) # works
---> 42 c.describe_palette(colors) # does not work

1 frames
<ipython-input-77-4264da0e7d08> in <listcomp>(.0)
     13     Describe colors in palette
     14     """
---> 15     descs = [describe_color(v) for v in vals]
     16     return descs
     17   def hex_to_rgb(self, color):

NameError: name 'describe_color' is not defined

有人知道为什么describe_color(color)有效但describe_palette(colors)不有效吗？

Answer 1

您必须从describe_palette方法返回值。另外，您必须使用self.

调用类实例方法

这是更正的程序：


class Colorparser:

    def describe_color(self, val):
        """Describe a color """
        color = self.parse_color(val)
        desc = "A description" # The real script does some crazy stuff here ;)
        return desc

    def describe_palette(self, vals):
        """Describe colors in palette"""
        descs = [self.describe_color(v) for v in vals]
        return descs

    def parse_color(self, val):
        """Returns an RGB tupple if color is RGB,
        and converts a hex color to RGB otherwise """

        if type(val) == str:
            color = self.hex_to_rgb(val)
        elif type(val) == list:
            color = val
        return color

    def hex_to_rgb(self, color):
        """Convertes a hex color to rgb"""
        value = color.lstrip('#')
        lv = len(value)
        return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))


c = Colorparser()

color = "#F7F7F7"
colors = ["#F7F7F7", "#F7F7F7"]

c.describe_color(color)
c.describe_palette(colors)

Answer 2

Python需要引用与“ self”相同的对象。以下应该起作用：

class Colorparser():

  def describe_color(self, val):
    """Describe a color """
    color = parse_color(val)
    desc = "A description" # The real script does some crazy stuff here ;)
    return desc 

  def describe_palette(self, vals):
    """Describe colors in palette"""
    descs = [self.describe_color(v) for v in vals] # <-- change in this line
    return descs

  def parse_color(self, val):
    """Returns an RGB tupple if color is RGB, 
    and converts a hex color to RGB otherwise """

    if type(val) == str:
      color = hex_to_rgb(val)
    elif type(val) == list:
      color = val
    return color 

  def hex_to_rgb(self, color):
    """Convertes a hex color to rgb"""
    value = color.lstrip('#')
    lv = len(value)
    return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))

我认为您从“ describe_color”进行的“ parse_color”调用也需要“ self”。字首。

为什么这个简单的颜色解析器不起作用？

2 个答案: