将移动的水平线添加到ipython交互式小部件

Question

根据找到here的教程，我试图创建一个IPython 2.0小部件，它可以让我向图像添加一条或多条水平线，然后根据滑块的运动垂直移动它们。我当前的尝试看起来像（来自IPython 2.0笔记本）：

from IPython.html.widgets import interact, interactive, fixed
from IPython.display import display
import skimage
from skimage import data, filter, io

i = data.coffee()
io.Image(i)

def add_lines(image, line1 = 100, line2 = 200):
  new_image = image
  new_image[line1,:,:] = 0
  new_image[line2,:,:] = 0
  new_image = io.Image(new_image)
  display(new_image)
  return new_image

lims = (0,400,2)
w = interactive(add_lines, image=fixed(i), line1 = lims, line2 = lims)
display(w)

结果如下：

相反，我希望图像使用相同的背景图像重绘，并根据滑块值更新行位置。使用IPython交互式窗口小部件机制，有没有办法重用“基础”图像并用新行重新绘制它？

如果重要，我当前安装的版本是：

$ ipython --version

2.0.0

$ python --version

Python 2.7.6 :: Anaconda 1.9.0（x86_64）

Answer 1

您应该处理原始图像的副本，如下所示：

from IPython.html.widgets import interact, interactive, fixed
from IPython.display import display
import skimage
from skimage import data, filter, io

i = data.coffee()

def add_lines(image, line1 = 100, line2 = 200):
  new_image = image.copy()  # Work on a copy
  new_image[line1,:,:] = 0
  new_image[line2,:,:] = 0
  new_image = io.Image(new_image)
  display(new_image)

lims = (0,400,2)
interactive(add_lines, image=fixed(i), line1 = lims, line2 = lims)