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HoloViews provides a really powerful link_selections transformation that automates the process of setting up linked selections across plots. This is a fairly sophisticated function that understands the semantics of how each plot type was generated from a source data set, and how selections in the plot’s local coordinates represent symbolic expressions that can be used to filter the original dataset. For more information, see the Linked Brushing section in the HoloViews documentation.,It’s even possible to combine the link_selections and datashade transformations to create linked visualizations across large datasets. This example shows how the two previous examples can be combined to support linking selections across a histogram and a datashaded scatter plot of 1.5 million points.,Dolly: Dolly occurs when the user’s point of view gets closer to (or further from) a UI element. Imagine a person with a camera walking up to a flower to get a closer shot.,The relationship between motion design and the UX of digital products is rapidly maturing. A principled approach to motion prevents undue reliance on the fleeting utility of trends, tools, and techniques. Better still, it spans the divide between the abstract motion of elements on 2D screens and the perception of movement in a 3D world.,With HoloViews, the datashade transformation can simply be applied to a scatter element without the need to write any callbacks defining how to re-evaluate the datashading operation in response to viewport changes.,Dimensionality makes it seem as though UI elements have multiple interactive sides, just like objects in the physical world. The behavior is achieved by making elements appear as if they are foldable, flippable, floating, or bestowed with realistic depth properties.,Now, the thing is that there is no single on/off switch in your body that inhibits all your motor neurons at once. Instead, the subsystems of your brain that handle sleep need to wrestle control from the subsystems that handle wakefulness. And sometimes, during this wrestling match, some motor neurons are fired randomly, causing your body to twitch.,For HoloViews users, Dash provides a new deployment technology with excellent scalability characteristics. In contrast to other technologies that can be used to deploy HoloViews dashboards (Bokeh, Panel, and Voila), Dash is unique in that it stores all user-level session data exclusively in the user’s web browser. This means that server memory requirements depend only on the app itself, and they do not increase linearly with the number of simultaneous users.,Interactive experiences demand motion in all its spry and subtle forms. When the principles of motion design are upheld, even the most rudimentary UI elements become sophisticated agents of human communication. When the principles are ignored, movement embodies characteristics not found in the natural world. No amount of aesthetic splendor can overcome the resulting clumsiness.,While the Plotly.js WebGL accelerated scatter trace can handle hundreds of thousands of points, Datashader can handle tens to hundreds of millions. The difference is that rather than passing the entire data set from the Python server to the browser for rendering, Datashader rasterizes the data set to a heatmap or image, and only transfers this heatmap or image to the browser for rendering.,Zoom: With zoom, the user’s point of view and the UI element remain fixed, but the element increases (or decreases) in size within the user’s screen. Now imagine that the person stays put and uses the camera’s zoom feature to make the flower appear larger.,Thanks to Dash HoloViews, the full power of the link_selections transformation can be used in Dash. Here is an example of linking a scatter plot to a histogram to visualize the classic iris data set.,Not only does Dash’s architecture make it possible for a single server to support many simultaneous users, it also makes it easy to horizontally scale an application across multiple servers using a load balancer like NGINX or Dash Enterprise Kubernetes.,To effectively use Datashader in an interactive context, it’s necessary to re-render the data set each time the figure viewport changes. This can already be accomplished in Dash by installing a callback function that listens for changes to the relayoutData prop, but coordinating the full update process is not straightforward.,Obscuration works the same way. It presents users with an interface that calls for interaction while simultaneously revealing a hint of the screen to follow. Navigation menus, passcode screens, and folder/file windows are common examples.