Interactive display of a 3d object in R

Question

I am still struggling to find a way in R to interactively display successive images.

In the following, I am generating a 3d object mat3d.

mat <- matrix(dnorm(seq(
  from = -10,
  to = 10,
  length.out = 100 * 100
), sd = 5),
c(100, 100))

mat2d <- mat * t(mat)

mat3d <- array(c(mat2d, mat2d * 0.9, mat2d * 0.8), c(100, 100, 3))

image(mat3d[, , 1],
      useRaster = TRUE,
      asp = 1,
      zlim = c(0, 0.01))

I would like to be able to display mat3d[, , 1], mat3d[, , 2], mat3d[, , k] by simply moving a cursor below the 2D image.

I would also like to be able to switch dimensions, so that I could display mat3d[, 1, ], mat3d[, 2, ], mat3d[, j, ], or mat3d[1, , ], mat3d[2, , ], mat3d[i, , ].

Can I obtain this using plotly or javascript in R?

Many thanks in advance for your help.

Answer 1

This is a good job for a Shiny app. Here is a starting point.

mat <- matrix(dnorm(seq(
  from = -10,
  to = 10,
  length.out = 100 * 100
), sd = 5),
c(100, 100))

mat2d <- mat * t(mat)

mat3d <- array(c(mat2d, mat2d * 0.9, mat2d * 0.8), c(100, 100, 3))


library(shiny)
ui <- fluidPage(
  fluidRow(
    column(
      12,
      radioButtons(
        "index", label = "Choose the index", 
        choices = c("1", "2", "3"), inline = TRUE
      )
    ),
    column(
      12,
      plotOutput("img")
    )    
  )
)

server <- function(input, output, session) {
  
  output[["img"]] <- renderPlot({
    index <- as.integer(input[["index"]])
    image(mat3d[, , index],
          useRaster = TRUE,
          asp = 1,
          zlim = c(0, 0.01))
  })
}

shinyApp(ui, server)

To display the three slices, I would do three images:

mat <- matrix(dnorm(seq(
  from = -10,
  to = 10,
  length.out = 100 * 100
), sd = 5),
c(100, 100))

mat2d <- mat * t(mat)

mat3d <- array(c(mat2d, mat2d * 0.9, mat2d * 0.8), c(100, 100, 3))

image(mat3d[70, , ],
      useRaster = TRUE,
      asp = 1,
      zlim = c(0, 0.01))

library(shiny)
ui <- fluidPage(
  fluidRow(
    column(
      4,
      numericInput(
        "ix", label = "Slice x", 
        min = 1, max = 100, step = 1, value = 50
      ),
      br(),
      plotOutput("imgx")
    ),
    column(
      4,
      numericInput(
        "iy", label = "Slice y", 
        min = 1, max = 100, step = 1, value = 20
      ),
      br(),
      plotOutput("imgy")
    ),
    column(
      4,
      radioButtons(
        "iz", label = "Slice z", 
        choices = c("1", "2", "3"), inline = TRUE
      ),
      br(),
      plotOutput("imgz")
    )
  )
)

server <- function(input, output, session) {
  
  output[["imgx"]] <- renderPlot({
    index <- input[["ix"]]
    image(mat3d[index, , ],
          useRaster = TRUE,
          asp = 1,
          zlim = c(0, 0.01))
  })
  
  output[["imgy"]] <- renderPlot({
    index <- input[["iy"]]
    image(mat3d[, index, ],
          useRaster = TRUE,
          asp = 1,
          zlim = c(0, 0.01))
  })
  
  output[["imgz"]] <- renderPlot({
    index <- as.integer(input[["iz"]])
    image(mat3d[, , index],
          useRaster = TRUE,
          asp = 1,
          zlim = c(0, 0.01))
  })
  
}

shinyApp(ui, server)