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NYC Taxi Crossfilter

Introduction

This vignette demonstrates a complex multi-view dashboard with crossfilter interactions. The example visualizes 1 million NYC taxi rides using: - Raster density maps for pickup and dropoff locations - Histogram of pickup times - Interactive brushing across all views

Example: NYC Taxi Rides with Crossfilter

library(rMosaic)

# Define the spec
taxi_spec <- list(
  meta = list(
    title       = "NYC Taxi Rides",
    description = paste(
      "Pickup/dropoff points for 1M NYC taxi rides on Jan 1–3, 2010.",
      "Drag to filter both maps.",
      "Requires DuckDB 'httpfs' + 'spatial' extensions.",
      sep = "\n"
    )
  ),
  config = list(extensions = c("httpfs", "spatial")),
  data = list(
    rides = list(
      file   = "https://idl.uw.edu/mosaic-datasets/data/nyc-rides-2010.parquet",
      select = c(
        "pickup_datetime::TIMESTAMP AS datetime",
        "ST_Transform(ST_Point(pickup_latitude, pickup_longitude),'EPSG:4326','ESRI:102718') AS pick",
        "ST_Transform(ST_Point(dropoff_latitude, dropoff_longitude),'EPSG:4326','ESRI:102718') AS drop"
      )
    ),
    trips = paste(
      "SELECT",
      "  (HOUR(datetime) + MINUTE(datetime)/60) AS time,",
      "  ST_X(pick) AS px, ST_Y(pick) AS py,",
      "  ST_X(drop) AS dx, ST_Y(drop) AS dy",
      "FROM rides",
      sep = "\n"
    )
  ),
  params = list(filter = list(select = "crossfilter")),
  vconcat = list(
    list(
      hconcat = list(
        # Left: pickup raster + brush
        list(
          plot = list(
            list(mark = "raster", data = list(from = "trips", filterBy = "$filter"),
                 x = "px", y = "py", bandwidth = 0),
            list(select = "intervalXY", as = "$filter"),
            list(mark = "text", data = list(list(label = "Taxi Pickups")),
                 dx = 10, dy = 10, text = "label",
                 fill = "black", fontSize = "1.2em",
                 frameAnchor = "top-left")
          ),
          width       = 335, height = 550,
          margin      = 0, xAxis = NULL, yAxis = NULL,
          xDomain     = c(975000, 1005000),
          yDomain     = c(190000, 240000),
          colorScale  = "symlog", colorScheme = "blues"
        ),
        # Spacer
        list(hspace = 10),
        # Right: dropoff raster + same brush
        list(
          plot = list(
            list(mark = "raster", data = list(from = "trips", filterBy = "$filter"),
                 x = "dx", y = "dy", bandwidth = 0),
            list(select = "intervalXY", as = "$filter"),
            list(mark = "text", data = list(list(label = "Taxi Dropoffs")),
                 dx = 10, dy = 10, text = "label",
                 fill = "black", fontSize = "1.2em",
                 frameAnchor = "top-left")
          ),
          width       = 335, height = 550,
          margin      = 0, xAxis = NULL, yAxis = NULL,
          xDomain     = c(975000, 1005000),
          yDomain     = c(190000, 240000),
          colorScale  = "symlog", colorScheme = "oranges"
        )
      )
    ),
    # Vertical space
    list(vspace = 10),
    # Histogram + brush
    list(
      plot = list(
        list(mark = "rectY", data = list(from = "trips", filterBy = "$filter"),
             x = list(bin = "time"),
             y = list(count = NULL),
             fill = "steelblue", inset = 0.5),
        list(select = "intervalX", as = "$filter")
      ),
      yTickFormat = "s",
      xLabel      = "Pickup Hour →",
      width       = 680,
      height      = 100
    )
  )
)

# Run the app
runMosaicApp(
  spec     = taxi_spec,
  specType = "yaml",
  data     = NULL,
  title    = "NYC Taxi Rides (Raster + Crossfilter)",
  backend  = "wasm"
)

Key Features

Crossfilter Selection

Remote Data Loading

Spatial Transformations

Performance

Try It Yourself

  1. Brush a region in the pickup map
  2. Notice the dropoff map and histogram update
  3. Brush a time range in the histogram
  4. See both maps update to show only rides in that time window

This demonstrates Mosaic’s ability to handle large datasets with fluid, interactive crossfilter selections.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.