# NGLVieweR

## Installation

NGLVieweR is available through GitHub

    install.packages("remotes")
    remotes::install_github("nvelden/NGLVieweR")

## Loading PDB files

You can load a PDB (or and other supported format) directly or use a PDB code of a structure on RCSB.org. The below minimal example loads the PDB file and displays the structure in a “cartoon” representation.

    #Load local pdb file
    NGLVieweR("C:/7CID.pdb") %>%
    addRepresentation("cartoon")
    #Load protein by PDB code
    NGLVieweR("7CID") %>%
    addRepresentation("cartoon")

Note: Use mouse for selection (left-click), rotate/move (left/right-click hold) and zooming (scroll wheel).

You can view a “basic” NGLVieweR Shiny application by running the below code. Use “API” for an example using API calls or any of the function names (e.g “addSelection”“) for function specific examples.

    library(NGLVieweR)
    library(shiny)
    NGLVieweR_example("basic")

## Loading other structural files

This package has been developed and tested using PDB files but supports loading of any of the following structural files: .mmcif, .cif, .mcif, .ent, .pqr, .gro, .sdf, .sd, .mol2 and .mmtf.

By default NGLVieweR guesses the file format from the file extension. Use the `format` parameter in case no or the wrong file extension is provided.

    #Note that line formatting needs to be exact when reading from console!
    benz <- "
    702
      -OEChem-02271511112D
      9  8  0     0  0  0  0  0  0999 V2000
        0.5369    0.9749    0.0000 O   0  0  0  0  0  0  0  0  0  0  0  0
        1.4030    0.4749    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
        2.2690    0.9749    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
        1.8015    0.0000    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
        1.0044    0.0000    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
        1.9590    1.5118    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
        2.8059    1.2849    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
        2.5790    0.4380    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
        0.0000    0.6649    0.0000 H   0  0  0  0  0  0  0  0  0  0  0  0
      1  2  1  0  0  0  0
      1  9  1  0  0  0  0
      2  3  1  0  0  0  0
      2  4  1  0  0  0  0
      2  5  1  0  0  0  0
      3  6  1  0  0  0  0
      3  7  1  0  0  0  0
      3  8  1  0  0  0  0
    M  END
    > <ID>
    00001
    > <DESCRIPTION>
    Solvent produced by yeast-based fermentation of sugars.
    $$$$
    "
    NGLVieweR(benz, format="sdf") %>%
      addRepresentation("ball+stick")

## Representations

You can load the structure as a “cartoon”, “ball+stick”, “line”, “surface”, “ribbon”, or any other representation listed in the NGL.js manual under “StructureRepresentation”. Multiple representations of the same structure can be overlaid by chaining the `addSelection()` function. Also see the “structure” tab in the demo app for a list of possible representations.

    NGLVieweR("7CID") %>%
    addRepresentation("cartoon") %>%
    addRepresentation("ball+stick")

You can alter the appearance of select residues using the `param` argument. For a full list of options see the NGL.js “RepresentationParameters” and the “Selection language” section.

    NGLVieweR("7CID") %>%
      addRepresentation("cartoon",
        param = list(colorScheme = "residueindex")
      ) %>%
      addRepresentation("ball+stick",
        param = list(
          sele = "233-248",
          colorValue = "red",
          colorScheme = "element"
        )
      ) %>%
      addRepresentation("surface",
        param = list(
          colorValue = "white",
          opacity = 0.1
        )
      )

## Structures

Using `addStructure()`, you can load multiple structures into the same stage. In this example, the first structure is represented in blue, while the second representation of the structure is represented in orange. Transformations such as `setPosition()`, `setRotation()`, and `setScale()` apply to the second (most recently added) structure.

    NGLVieweR("1CRN") %>%
      addRepresentation("cartoon", param = list(color = "blue")) %>%
      addStructure("1CRN") %>%
      addRepresentation("cartoon", param = list(color = "orange")) %>%
      setPosition(x = 20, y = 0, z = 0) %>%
      setRotation(x = 2, y = 0, z = 0, degrees = FALSE) %>%
      setScale(0.5)

## Superpose

Structures can be superposed onto each other using the `setSuperpose()` function. It aligns the structures by specifying a reference structure (defaulting to the first one loaded) and defining the selections within each structure to be used for alignment.

    NGLVieweR("1GZM") %>%
       addRepresentation("cartoon", param = list(color = "blue")) %>%
       addStructure("1U19") %>%
       addRepresentation("cartoon", param = list(color = "orange")) %>%
       setSuperpose(
         reference = 1,
         sele_reference = ":A",
         sele_target = ":A",
         superpose = TRUE
         )

## Stage

You can alter the background color or set the zoom or rotation speed using the `stageParameters()` function. For a full list of options, see the “StageParameters” method in the official NGL.js manual. In additions there are specific functions to set:

- Animation: `setRock()` or `setSpin()`
- Focus: `setFocus()`
- Quality: `setQuality()`

Note: Changes in background color are not visible in the RStudio viewer.

    NGLVieweR("7CID") %>%
      stageParameters(backgroundColor = "white", zoomSpeed = 1) %>%
      addRepresentation("cartoon",
        param = list(name = "cartoon", colorScheme = "residueindex")
      ) %>%
      setSpin()

## Labels

Labels can be added by setting the `addRepresentation()` type parameter to “label”. For a full list of of options, see the LabelRepresentationParameters section in the NGL.js manual. Also see the “label” tab in the demo app for possible label settings.

    NGLVieweR("7CID") %>%
      addRepresentation("cartoon") %>%
      addRepresentation("ball+stick", param = list(
        colorScheme = "element",
        colorValue = "yellow",
        sele = "20"
      )) %>%
      addRepresentation("label",
        param = list(
          sele = "20",
          labelType = "format",
          labelFormat = "[%(resname)s]%(resno)s", # or enter custom text
          labelGrouping = "residue", # or "atom" (eg. sele = "20:A.CB")
          color = "white",
          fontFamiliy = "sans-serif",
          xOffset = 1,
          yOffset = 0,
          zOffset = 0,
          fixedSize = TRUE,
          radiusType = 1,
          radiusSize = 1.5, # Label size
          showBackground = FALSE
          # backgroundColor="black",
          # backgroundOpacity=0.5
        )
      )

## Transformation functions

The package provides a set of transformation functions that allow for adjusting the scale, rotation, and position of the visualized structures.

### Scaling Structures

The `setScale()` function allows you to adjust the scale of the visualized structure:

    NGLVieweR("7CID") %>%
    addRepresentation("cartoon") %>%
    setScale(2) # Doubles the size of the structure

### Rotating Structures

You can rotate the visualized structures using the `setRotation()` function:

    NGLVieweR("7CID") %>%
    addRepresentation("cartoon") %>%
    setRotation(30, 45, 60) # Rotates the structure 30 degrees around x-axis, 45 degrees around y-axis and 60 degrees around z-axis.

### Positioning Structures

The `setPosition()` function allows you to change the position of the visualized structure:

    NGLVieweR("7CID") %>%
    addRepresentation("cartoon") %>%
    setPosition(25, 0, 0) # Moves the structure 25 units along the x-axis.

## Zoom

You can zoom into specific residues using the `ZoomMove()` function.

    NGLVieweR("7CID") %>%
      addRepresentation("cartoon") %>%
      addRepresentation("ball+stick",
        param = list(
          colorScheme = "element",
          colorValue = "yellow",
          sele = "20"
        )
      ) %>%
      addRepresentation("label",
        param = list(
          sele = "20",
          labelType = "format",
          labelFormat = "[%(resname)s]%(resno)s", # or enter custom text
          labelGrouping = "residue", # or "atom" (eg. sele = "20:A.CB")
          color = "white",
          xOffset = 1,
          fixedSize = TRUE,
          radiusType = 1,
          radiusSize = 1.5
        ) # Label size
      ) %>%
      zoomMove(
        center = "20",
        zoom = "20",
        duration = 0, # animation time in ms
        z_offSet = -20
      )

## Contact

Contacts between residues can be added by setting the `addRepresentation()` type parameter to “contact”. Using the `sele` parameter contacts for specific residues can be selected. The `filterSele` parameter can be used to only show contacts between two selections. In the below example Biotin and residues 23, 27, 43, 45, and 128 are selected `sele="5001 or 23 or 27 or 43 or 45 or 128"` and contacts are only shown between the residues and biotin `filterSele=list("23 or 27 or 43 or 45 or 128", "5001")`. This prevents the display of contacts between residues or water molecules.

    NGLVieweR("3RY2") %>%
      addRepresentation("cartoon") %>%
      addRepresentation("ball+stick",
        param = list(
          name = "biotin",
          colorvalue = "grey",
          colorScheme = "element",
          sele = "5001"
        )
      ) %>%
      addRepresentation("ball+stick",
        param = list(
          name = "interacting",
          colorScheme = "element",
          colorValue = "green",
          sele = "23 or 27 or 43 or 45 or 128"
        )
      ) %>%
      zoomMove(
        center = "27:B",
        zoom = "27:B",
        z_offSet = -20
      ) %>%
      addRepresentation("contact",
        param = list(
          name = "contact",
          sele = "5001 or 23 or 27 or 43 or 45 or 128",
          filterSele = list("23 or 27 or 45 or 128", "5001"),
          labelVisible = TRUE,
          labelFixedSize = FALSE,
          labelUnit = "angstrom", # "", "angstrom", "nm"
          labelSize = 2
          # hydrogenBond=TRUE,
          # weakHydrogenBond=FALSE,
          # waterHydrogenBond=FALSE,
          # backboneHydrogenBond=TRUE,
          # hydrophobic=FALSE,
          # halogenBond=TRUE,
          # ionicInteraction=TRUE,
          # metalCoordination=TRUE,
          # cationPi=TRUE,
          # piStacking=TRUE,
          # maxHydrophobicDist= 4.0,
          # maxHbondDist= 3.5,
          # maxHbondSulfurDist= 4.1,
          # maxHbondAccAngle= 45,
          # maxHbondDonAngle= 45,
          # maxHbondAccPlaneAngle= 90,
          # maxHbondDonPlaneAngle= 30,
          # maxPiStackingDist= 5.5,
          # maxPiStackingOffset= 2.0,
          # maxPiStackingAngle= 30,
          # maxCationPiDist= 6.0,
          # maxCationPiOffset= 2.0,
          # maxIonicDist= 5.0,
          # maxHalogenBondDist= 3.5,
          # maxHalogenBondAngle= 30,
          # maxMetalDist= 3.0,
          # refineSaltBridges= TRUE,
          # masterModelIndex= -1,
          # lineOfSightDistFactor= 1
        )
      )

## Shiny

The `NGLVieweROutput()` and `renderNGLVieweR()` functions enable you to visualize PDB files within Shiny applications. See the `NGLVieweR_example("basic")` and “API” for live examples.

    library(shiny)
    library(NGLVieweR)
    ui <- fluidPage(NGLVieweROutput("structure"))
    server <- function(input, output) {
      output$structure <- renderNGLVieweR({
        NGLVieweR("7CID") %>%
          addRepresentation("cartoon",
            param = list(
              name = "cartoon", color =
                "residueindex"
            )
          ) %>%
          addRepresentation("ball+stick",
            param = list(
              name = "cartoon",
              sele = "1-20",
              colorScheme = "element"
            )
          ) %>%
          stageParameters(backgroundColor = "black") %>%
          setQuality("high") %>%
          setFocus(0) %>%
          setSpin(TRUE)
      })
    }
    shinyApp(ui, server)

A basic NGLVieweR Shiny app

## API

In Shiny apps, you can manipulate the NGLVieweR widget after creation using specific “API” calls. You can for instance add or remove representations by referring to their name using the `addSelection()` or `removeSelection()` functions.

    library(shiny)
    library(NGLVieweR)

    ui <- fluidPage(
      titlePanel("Viewer with API inputs"),
      sidebarLayout(
        sidebarPanel(
          textInput("selection", "Selection", "1-20"),
          selectInput("type", "Type", c("ball+stick", "cartoon", "backbone")),
          selectInput("color", "Color", c("orange", "grey", "white")),
          actionButton("add", "Add"),
          actionButton("remove", "Remove")
        ),
        mainPanel(
          NGLVieweROutput("structure")
        )
      )
    )

    server <- function(input, output) {
      output$structure <- renderNGLVieweR({
        NGLVieweR("7CID") %>%
          addRepresentation("cartoon",
                            param = list(name = "cartoon", colorScheme = "residueindex")
          ) %>%
          stageParameters(backgroundColor = input$backgroundColor) %>%
          setQuality("high") %>%
          setFocus(0) %>%
          setSpin(TRUE)
      })

      observeEvent(input$add, {
        if (isolate(input$type) == "cartoon") {
          # For cartoon, use the color parameter
          NGLVieweR_proxy("structure") %>%
            addSelection(isolate(input$type),
                         param = list(
                           name = "sel1",
                           sele = isolate(input$selection),
                           color = isolate(input$color)
                         )
            )
        } else {
          # For other types, use colorValue
          NGLVieweR_proxy("structure") %>%
            addSelection(isolate(input$type),
                         param = list(
                           name = "sel1",
                           sele = isolate(input$selection),
                           colorValue = isolate(input$color)
                         )
            )
        }
      })

      observeEvent(input$remove, {
        NGLVieweR_proxy("structure") %>%
          removeSelection("sel1")
      })
    }

    shinyApp(ui, server)

NGLVieweR API in Shiny

### Possible API functions are:

- `addSelection()`
- `removeSelection()`
- `snapShot()`
- `updateColor()`
- `updateFocus()`
- `updateFullscreen()`
- `updateRepresentation()`
- `updateRock()`
- `updateSelection()`
- `updateSpin()`
- `updateStage()`
- `updateVisibility()`
- `updateZoomMove()`

## Retrieving data from the widget

In a Shiny application one can retrieve information from the widget as inputs based on the NGLVieweR `outputID`. Suppose the `outputID` is “structure”, then the following information can be retrieved:

- input$structure_selection - Get details on the clicked residue.
- input$structure_sequence - will return the sequence of the PDB file as a character vector.
- input$structure_resno - will return all the sequence numbers as a numeric vector.
- input$structure_chainname - will return the chainname of each amino acid as a character vector,
- input$structure_rendering - will return `TRUE` if the widget is loading or `FALSE` when completed.
- input$structure_PDB - will return the PDB file as a text string.
- input$structure_selAround - will return a list of atoms surrounding a clicked residue.

In the below example a label, all contacts and residues in proximity of the clicked residue are displayed.

    library(shiny)
    library(NGLVieweR)
    library(stringr)

    ui <- fluidPage(
      titlePanel("Viewer with click interaction"),
      sidebarLayout(
        sidebarPanel(verbatimTextOutput('selection')),
        mainPanel(NGLVieweROutput("structure"))
      )
    )

    server <- function(input, output) {
      output$structure <- renderNGLVieweR({
        NGLVieweR("3RY2") %>%
          addRepresentation("cartoon") %>%
          addRepresentation(
            "ball+stick",
            param = list(
              name = "biotin",
              colorvalue = "grey",
              colorScheme = "element",
              sele = "5001"
            )
          ) %>%
          zoomMove(center = "27:B",
                   zoom = "27:B",
                   z_offSet = -20) %>%
          selectionParameters(3, "residue") #"atom"
      })

      #Save click selections
      sele <- reactiveValues()

      observe({
        sele$aa <-
          str_extract(input$structure_selection, "(?<=[\\[])(.*?)(?=\\])")
        sele$aa_bond <-
          str_extract(input$structure_selection, "(?<=[\\]])(.*?)(?=[:space:])")
        sele$resiChain <-
          str_extract(input$structure_selection, "(?<=[]])(.*?)(?=[.])")
        sele$resi <-
          str_extract(input$structure_selection, "(?<=[]])(.*?)(?=[:])")
        sele$fileName <-
          str_extract(input$structure_selection, "(?<=[(])(.*?)(?=[.])")
      })

      output$selection = renderPrint({
        #Full selection
        print(input$structure_selection)
        #Amino Acid
        print(sele$aa)
        #Bond
        print(sele$aa_bond)
        #Residue number + ChainNAme
        print(sele$resiChain)
        #Residue number
        print(sele$resi)
        #PDB name
        print(sele$fileName)
        #SelAround
        print(input$structure_selAround)
      })

      observeEvent(input$structure_selAround, {
        NGLVieweR_proxy("structure") %>% removeSelection("selAround")

        NGLVieweR_proxy("structure") %>%
          addSelection(
            "ball+stick",
            param =
              list(
                name = "selAround",
                sele = input$structure_selAround,
                colorValue = "grey"
              )
          )

      })

      observeEvent(sele$resiChain, {
        #Remove any selections
        NGLVieweR_proxy("structure") %>% removeSelection("label")
        NGLVieweR_proxy("structure") %>% removeSelection("contact")

        #Add label and contacts
        NGLVieweR_proxy("structure") %>%

          addSelection(
            "label",
            param = list(
              name = "label",
              sele = sele$resiChain,
              labelType = "format",
              labelFormat = "[%(resname)s]%(resno)s",
              # or enter custom text
              labelGrouping = "residue",
              # or "atom" (eg. sele = "20:A.CB")
              color = "white",
              xOffset = 1,
              fixedSize = TRUE,
              radiusType = 1,
              radiusSize = 1.5
            )
          ) %>%
          addSelection(
            "contact",
            param = list(
              name = "contact",
              sele = "*",
              #Select all residues
              filterSele =
                list(sele$resiChain, # Show bonds between selected residue
                     "*"),
              # and all other residues
              labelVisible = TRUE,
              labelFixedSize = FALSE,
              labelUnit = "angstrom",
              # "", "angstrom", "nm"
              labelSize = 2
            )
          )
      })

    }
    shinyApp(ui, server)

Click interaction example in NGLVieweR