具有流的HoloViews DynamicMap仅将显示输出传递给IPython一次

Question

我在流函数内部的代码上苦苦挣扎，只将其传递给IPython一次。换句话说，从DynamicMap进行的display()调用仅执行一次（click = hv.DynamicMap(interactive_click, streams=[SingleTap()])）。

这只是一个简单的示例，但是在我的实际用例中，我那里需要执行display(Javascript(''))代码。

# problem: display statement not returned to Jupyter Notebook
import numpy as np
import holoviews as hv
from holoviews import opts
from holoviews.streams import SingleTap
# from IPython.display import Javascript
hv.extension('bokeh')

# triggered when clicking on a plot
def interactive_click(x, y):
    # problem: Only executed once
    display("init")
    if None not in [x, y]:
        # problem: never executed, because `display()` is not passed to Jupyter Notebook
        display(x)
    else:
        x = 0
    return hv.VLine(x).opts(color='green')

# random plot: http://holoviews.org/reference/elements/bokeh/Image.html
ls = np.linspace(0, 10, 200)
xx, yy = np.meshgrid(ls, ls)

bounds=(-1,-1,1,1)   # Coordinate system: (left, bottom, right, top)
img = hv.Image(np.sin(xx)*np.cos(yy), bounds=bounds)

# do something when clicked on plot
click = hv.DynamicMap(interactive_click, streams=[SingleTap()])

# show plot and trigger code on-press
img * click

display("init")仅在输出单元格中显示一次，display(x)从不显示（因为第一个输入为(None, None)）。这只是一个简单的示例，但是在我的情况下，我想执行Javascript，但是只有在display()输出传递到IPython内核时才能执行。

我知道代码已执行，因为图中的绿线移动了：

问题

任何人都知道如何在给定的示例中使display(x)显示输出（这意味着显示输出将传递到Jupyter Notebook中的IPython内核）？

Answer 1

在pyviz Gitter上@philippjfr暗示，display_id使解决方案成为可能。

我们在def interactive_click(x, y)上方添加以下代码：

# create a display that we later update
display("None", display_id="click_value")

并将display(x)更新为display(x, display_id="click_value")

如果现在单击图，我们将看到鼠标单击的x值“无”更改。

这也适用于Javascript： display(Javascript('element.text("test");'), display_id="click_value")

---

完整代码：

# problem: display statement not returned to Jupyter Notebook
import numpy as np
import holoviews as hv
from holoviews import opts
from holoviews.streams import SingleTap
# from IPython.display import Javascript
hv.extension('bokeh')

# create a display that we later update
display("None", display_id="click_value")

# triggered when clicking on a plot
def interactive_click(x, y):
    # problem: Only executed once
    # display("init")
    if None not in [x, y]:
        # problem solved
        display(x, display_id="click_value")
        # display(Javascript('element.text("test");'), display_id="click_value")
    else:
        x = 0
    return hv.VLine(x).opts(color='green')

# random plot: http://holoviews.org/reference/elements/bokeh/Image.html
ls = np.linspace(0, 10, 200)
xx, yy = np.meshgrid(ls, ls)

bounds=(-1,-1,1,1)   # Coordinate system: (left, bottom, right, top)
img = hv.Image(np.sin(xx)*np.cos(yy), bounds=bounds)

# do something when clicked on plot
click = hv.DynamicMap(interactive_click, streams=[SingleTap()])

# show plot and trigger code on-press
img * click