diff --git a/DESCRIPTION b/DESCRIPTION
index 2313af3..88c8485 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: DataMan
 Type: Package
-Title: This is an R package for data and model analysis
+Title: a R package for data and model analysis
 Version: 0.4.1
 Date: 2015-12-04
 Author: Sixiang Hu <sixiang.hu@gmail.com>
@@ -15,6 +15,7 @@ Imports:
     Rcpp (>= 0.11.6),
     dplyr,
     rbokeh,
+    plotly,
     ROCR,
     gbm,
     randomForest
diff --git a/NAMESPACE b/NAMESPACE
index 043ba46..6f97029 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,7 +1,4 @@
 # Generated by roxygen2: do not edit by hand
-useDynLib(DataMan)
-importFrom(Rcpp, evalCpp)
-exportPattern("^[[:alpha:]]+")
 
 S3method(CramersV,data.frame)
 S3method(CramersV,default)
@@ -27,6 +24,7 @@ export(DataSummary)
 export(DetMiss)
 export(PopMiss)
 export(dataPlot)
+export(interPlot)
 export(liftPlot)
 export(modelPlot)
 export(resiPlot)
@@ -34,15 +32,20 @@ export(rocPlot)
 export(tree2data)
 importFrom(ROCR,performance)
 importFrom(ROCR,prediction)
+importFrom(Rcpp,evalCpp)
 importFrom(data.table,":=")
 importFrom(data.table,as.data.table)
 importFrom(data.table,data.table)
+importFrom(data.table,dcast)
+importFrom(data.table,key)
 importFrom(data.table,setkey)
 importFrom(dplyr,"%>%")
 importFrom(dplyr,group_by)
 importFrom(dplyr,left_join)
 importFrom(dplyr,summarise)
 importFrom(gbm,pretty.gbm.tree)
+importFrom(plotly,layout)
+importFrom(plotly,plot_ly)
 importFrom(randomForest,getTree)
 importFrom(rbokeh,figure)
 importFrom(rbokeh,grid_plot)
@@ -52,3 +55,4 @@ importFrom(rbokeh,ly_hist)
 importFrom(rbokeh,ly_lines)
 importFrom(rbokeh,ly_points)
 importFrom(rbokeh,y_axis)
+useDynLib(DataMan)
diff --git a/NEWS.Rmd b/NEWS.md
similarity index 87%
rename from NEWS.Rmd
rename to NEWS.md
index 02c43b1..ec330ee 100644
--- a/NEWS.Rmd
+++ b/NEWS.md
@@ -2,6 +2,8 @@ DataMan 0.4.1
 -------------------------------------------------------------
 NEW FEATURES
 
+* Add `interPlot` that gives 3D surface plot utilising `plotly` package.
+
 * Add `liftPlot` that compares different model predictions.
 
 * Add `rocPlot` that assesses binary classification under `ROCR` package. It plots ROC curves with one or more predictions. AUC will be calculated and showed in legend.
@@ -17,3 +19,5 @@ BUG FIXES AND MINOR IMPROVEMENTS
 * Change the glyphs of points in `modelPlot`
 
 * Change `.travis.yaml` to install `rbokeh` from github.
+
+* Improve the `PopMiss`.
diff --git a/R/DataMan.R b/R/DataMan.R
index e69de29..cd54e90 100644
--- a/R/DataMan.R
+++ b/R/DataMan.R
@@ -0,0 +1,8 @@
+#' DataMan a data clearning, analysis and statistical modeling assessing tool
+#' 
+#' @description a data clearning, analysis and statistical modeling assessing tool.
+#' @docType package
+#' @name DataMan
+#' @useDynLib DataMan
+#' @importFrom Rcpp evalCpp
+NULL
\ No newline at end of file
diff --git a/R/PopMiss.r b/R/PopMiss.r
index 870c453..1e97c8e 100644
--- a/R/PopMiss.r
+++ b/R/PopMiss.r
@@ -2,7 +2,7 @@
 #'
 #' @description This function allows you to populate missing values. 
 #' @usage PopMiss(data,na.treatment=c("mean.or.mode","delete","replace"),replace=NULL)
-#' @param data This could be data frame, matrix or a vector.
+#' @param data This could be data frame,data.table, matrix or a vector.
 #' @param na.treatment One of "mean.or.mode", "delete", or "replace", to specify the method to populate missing values.
 #' @param replace A single value used for populating ALL missing value.  May not be useful for a data frame with missing values in different type of variable. 
 #' @seealso DetMiss
@@ -13,7 +13,13 @@
 #' PopMiss(a,"mean.or.mode")
 
 PopMiss <- function(data,na.treatment=c("mean.or.mode","delete","replace"),replace=NULL){
+  if (is.null(na.treatment)) na.treatment <- "mean.or.mode"
+  
   na.treatment <- match.arg(na.treatment)
+  
+  if ((na.treatment %in% c("replace","r")) && is.null(replace)) 
+    stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
+  
   UseMethod("PopMiss",data)
 }
 
@@ -27,14 +33,13 @@ PopMiss.factor<-function(data,na.treatment,replace){
 #' @rdname PopMiss
 PopMiss.character<-function(data,na.treatment,replace){
   num_miss <- sum(is.na(data))
-  if(isTRUE(na.treatment=="delete")) {
+  if(identical(na.treatment,"delete")) {
     return(data[!is.na(data)])
   }
-  else if(isTRUE(na.treatment=="mean.or.mode")){
+  else if(identical(na.treatment,"mean.or.mode")){
     replace <- names(table(data))[order(table(data),decreasing=TRUE)[1]]
   }
   
-  if (is.null(replace)) stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
   data[is.na(data)] <- replace
   return(data)
 }
@@ -43,13 +48,12 @@ PopMiss.character<-function(data,na.treatment,replace){
 #' @rdname PopMiss
 PopMiss.integer<-function(data,na.treatment,replace){
   num_miss <- length(which(is.na(data)))
-  if(isTRUE(na.treatment=="delete")) {
+  if(identical(na.treatment,"delete")) {
     return(na.omit(data))
   }
-  else if(isTRUE(na.treatment=="mean.or.mode")){
+  else if(identical(na.treatment,"mean.or.mode")){
     replace <- floor(mean(data,na.rm=TRUE))
   }
-  if (is.null(replace)) stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
   data[is.na(data)] <- replace
   return(data)
 }
@@ -64,17 +68,13 @@ PopMiss.Date<-function(data,na.treatment,replace){
 #' @rdname PopMiss
 PopMiss.numeric<-function(data,na.treatment,replace){
   num_miss <- length(which(is.na(data)))
-  if(isTRUE(na.treatment=="delete")) {
-    cat(paste(num_miss," rows have been delete.\n\n"))
+  if(identical(na.treatment,"delete")) {
         return(na.omit(data))
   }
-  else if(isTRUE(na.treatment=="mean.or.mode")){
+  else if(identical(na.treatment,"mean.or.mode")){
     replace <- mean(data,na.rm=TRUE)
   }
-  if (is.null(replace)) stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
-  
   data[is.na(data)] <- replace
-  cat(paste(num_miss," row have been populated by value:",replace,".\n\n"))
   return(data)
 }
 
@@ -82,31 +82,31 @@ PopMiss.numeric<-function(data,na.treatment,replace){
 #' @rdname PopMiss
 PopMiss.data.frame<-function(data,na.treatment,replace){
   num_miss <- which(sapply(data,function(x) any(is.na(x))))
-  if(isTRUE(na.treatment=="delete")) {
+  if(identical(na.treatment,"delete")) {
     return(na.omit(data))
   }
-  else if(isTRUE(na.treatment=="mean.or.mode")){
-    str_name <- names(data)
-    for(i in num_miss){
-      if(class(data[,str_name[i]]) %in% c("character","Date","factor"))
-        replace <- names(table(data[,str_name[i]]))[order(table(data[,str_name[i]]),decreasing=TRUE)[1]]
-      else if(class(data[,str_name[i]])=="integer" )
-        replace <- floor(mean(data[,str_name[i]],na.rm=TRUE))
+  else if(identical(na.treatment,"mean.or.mode")){
+    ind <- dim(data)[2]
+    for(i in 1:ind){
+      if(class(data[[i]]) %in% c("character","Date","factor"))
+        replace <- names(table(data[[i]]))[order(table(data[[i]]),decreasing=TRUE)[1]]
+      else if(class(data[[i]])=="integer" )
+        replace <- floor(mean(data[[i]],na.rm=TRUE))
       else 
-        replace <- mean(data[,str_name[i]],na.rm=TRUE)
-      data[is.na(data[,str_name[i]]),str_name[i]] <- replace
+        replace <- mean(data[[i]],na.rm=TRUE)
+      data[[i]][is.na(data[[i]])] <- replace
     }
     
     return(data)
   }
   else{
-    if (is.null(replace)) stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
-    
     warning("Provided replacement will be used for all missing value.")
-    str_name <- names(data)
-    for(i in num_miss){
-    	if ("Date" %in% class(data[,str_name[i]]) ) data[is.na(data[,str_name[i]]),str_name[i]] <- as.Date("1960-01-01")	
-      	else data[is.na(data[,str_name[i]]),str_name[i]] <- replace
+    ind <- dim(data)[2]
+    for(i in 1:ind){
+    	if ("Date" %in% class(data[[i]]) ) 
+    	  data[[i]][is.na(data[[i]])] <- as.Date("1960-01-01")	
+      else 
+        data[[i]][is.na(data[[i]])] <- replace
     }
     return(data)
   }
@@ -115,42 +115,14 @@ PopMiss.data.frame<-function(data,na.treatment,replace){
 #' @export
 #' @rdname PopMiss
 PopMiss.data.table <-function(data,na.treatment,replace){
-  num_miss <- which(data[,sapply(.SD,function(x) any(is.na(x)))])
-  if(isTRUE(na.treatment=="delete")) {
-    return(na.omit(data))
-  }
-  else if(isTRUE(na.treatment=="mean.or.mode")){
-    str_name <- names(data)
-    for(i in num_miss){
-      if( data[,class(get(str_name[i]))] %in% c("character","Date","factor"))
-        replace <- as.data.frame(data[,.N,get(str_name[i])][order(-N)])[1,1]
-      else if( data[,class(get(str_name[i]))]=="integer" )
-        replace <- data[,floor(mean(get(str_name[i]),na.rm=TRUE))]
-      else 
-        replace <- data[,mean(get(str_name[i]),na.rm=TRUE)]
-      
-      data[which(is.na(data[,i,with=FALSE])),i] <- replace
-    }
-    
-    return(data)
-  }
-  else{
-    if (is.null(replace)) stop("NULL value used for populating NAs. Chosen \"replace\" method, but didn't provide a value for replace parameter?")
-    
-    warning("Provided replacement will be used for all missing value.")
-    str_name <- names(data)
-    for(i in num_miss){
-     	if ("Date" %in% class(data[,i,with=FALSE])) data[which(is.na(data[,i,with=FALSE])),i] <- as.Date("1960-01-01")	
-      	data[which(is.na(data[,i,with=FALSE])),i] <- replace
-    }
-    return(data)
-  }
+  PopMiss.data.frame(data,na.treatment,replace)
 }
 
 #' @export
 #' @rdname PopMiss
 PopMiss.matrix <- function(data,na.treatment,replace){
-	if(identical(na.treatment,"delete")) warning("na.treatment is \"delete\" and 'data' is a matrix. This only works correctly if whole rows are missing")
+	if(identical(na.treatment,"delete")) 
+	  warning("na.treatment is \"delete\" and 'data' is a matrix. This only works correctly if whole rows are missing")
 	matrix(PopMiss(as.vector(data),na.treatment,replace),ncol=ncol(data))
 }
 
diff --git a/R/RcppExports.R b/R/RcppExports.R
index b167beb..f553241 100644
--- a/R/RcppExports.R
+++ b/R/RcppExports.R
@@ -1,12 +1,10 @@
 # This file was generated by Rcpp::compileAttributes
 # Generator token: 10BE3573-1514-4C36-9D1C-5A225CD40393
 
-#' @rdname CramersV
 CramersV_C <- function(x, y) {
     .Call('DataMan_CramersV_C', PACKAGE = 'DataMan', x, y)
 }
 
-#' @rdname CramersV
 CramersV_DF <- function(dm) {
     .Call('DataMan_CramersV_DF', PACKAGE = 'DataMan', dm)
 }
diff --git a/R/dataPlot.r b/R/dataPlot.r
index 972e245..e6a8739 100644
--- a/R/dataPlot.r
+++ b/R/dataPlot.r
@@ -78,6 +78,9 @@ dataPlot <- function(data,xvar,yvar,byvar=NULL,weights=NULL,
                     length.out=newGroupNum
                     )
     x <- cut(x,new_band,include.lowest = TRUE)
+    
+    # solve the order issue when plotting using rbokeh.
+    # can also set the label in cut function.
     x <- as.character(paste(as.integer(x),as.character(x),sep=";"))
   }
 
diff --git a/R/interPlot.R b/R/interPlot.R
new file mode 100644
index 0000000..c8800c4
--- /dev/null
+++ b/R/interPlot.R
@@ -0,0 +1,60 @@
+#' interPlot
+#'
+#' @description Interactive 3D plot by calling `plotly` package functions.
+#' @usage interPlot(data,xvar,yvar,zvar)
+#' @param data a data frame.
+#' @param xvar either an integer to specify the position of the variable in the data frame, or the name of the variable.
+#' @param yvar either an integer to specify the position of the variable in the data frame, or the name of the variable.
+#' @param zvar either an integer to specify the position of the variable in the data frame, or the name of the variable.
+#' @details This functions gives a 3D interactive view of between factors.
+#' This is really useful when modeller wants to assess the interaction terms.
+#' Hence the "zvar" can be actual response data or model predictions.
+#' @author Sixiang Hu
+#' @importFrom data.table data.table setkey key := dcast
+#' @importFrom plotly plot_ly layout
+#' @export interPlot
+#' @examples
+#' 
+#' interPlot(mtcars,"wt","mpg","vs")
+
+interPlot <- function(data,xvar,yvar,zvar){
+  # Error Trap
+  if( .isDFnull(data) ) stop("data set provided is null.")
+  if( is.null(xvar) ) stop("X variable provided is null.") 
+  if( is.null(yvar) ) stop("Y variable provided is null.")
+  if( is.null(zvar) ) stop("Z variable provided is null.")
+  
+  # Find data column
+  posi <- .VarPosition(data,xvar)
+  x <- data[[posi$posi]]
+
+  posi <- .VarPosition(data,yvar)
+  y <- data[[posi$posi]]
+
+  posi <- .VarPosition(data,zvar)
+  z <- data[[posi$posi]]
+  
+  dt <- data.table::data.table(x = x,
+                   y = y,
+                   z = z)
+  data.table::setkey(dt,x,y)
+  
+  dt2 <- data.table::dcast(dt,x~y,fun.aggregate=mean,
+                           na.rm=TRUE,
+                           value.var="z",
+                           drop=FALSE)
+  
+  zvalue <- suppressWarnings(DataMan::PopMiss(as.matrix(dt2[,-1,with=FALSE]),
+                                     na.treatment = "replace",
+                                     0))
+
+  plotly::plot_ly(
+          x=dt2[[1]],
+          y=colnames(dt2),
+          z=zvalue, 
+          type = "surface",
+          showlegend=FALSE) %>%
+    plotly::layout(xaxis=list(title=xvar),
+           yaxis=list(title=yvar),
+           zaxis=list(title=zvar))
+}
\ No newline at end of file
diff --git a/man/CramersV.Rd b/man/CramersV.Rd
index fba529f..7fa000e 100644
--- a/man/CramersV.Rd
+++ b/man/CramersV.Rd
@@ -1,12 +1,10 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/CramersV.r, R/RcppExports.R
+% Please edit documentation in R/CramersV.r
 \name{CramersV}
 \alias{CramersV}
 \alias{CramersV.data.frame}
 \alias{CramersV.default}
 \alias{CramersV.matrix}
-\alias{CramersV_C}
-\alias{CramersV_DF}
 \title{Cramers' V Test}
 \usage{
 CramersV(x,y=NULL)
@@ -16,10 +14,6 @@ CramersV(x,y=NULL)
 \method{CramersV}{data.frame}(x, y = NULL)
 
 \method{CramersV}{matrix}(x, y = NULL)
-
-CramersV_C(x, y)
-
-CramersV_DF(dm)
 }
 \arguments{
 \item{x}{It could be non-numerical variable, data.frame or matrix.}
diff --git a/man/DataMan-package.Rd b/man/DataMan-package.Rd
deleted file mode 100644
index dbde310..0000000
--- a/man/DataMan-package.Rd
+++ /dev/null
@@ -1,23 +0,0 @@
-\name{DataMan-package}
-\alias{DataMan-package}
-\alias{DataMan}
-\docType{package}
-\title{
-This is an R package for data cleaning and preliminary data analysis.
-}
-\description{
-This package provides some simple function used for: Data Cleaning - detecting and populating missing value in a given data frame or vector; Data Analysis - an enhanced summary function to provide more info about variables in the given data. 
-}
-\details{
-\tabular{ll}{
-Package: \tab DataMan\cr
-Type: \tab Package\cr
-Version: \tab 0.1\cr
-Date: \tab 2014-12-23\cr
-License: \tab GPL 2\cr
-}
-}
-\author{
-Sixiang Hu <Sixiang.Hu@Gmail.Com>
-}
-
diff --git a/man/DataMan.Rd b/man/DataMan.Rd
new file mode 100644
index 0000000..d643102
--- /dev/null
+++ b/man/DataMan.Rd
@@ -0,0 +1,11 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/DataMan.R
+\docType{package}
+\name{DataMan}
+\alias{DataMan}
+\alias{DataMan-package}
+\title{DataMan a data clearning, analysis and statistical modeling assessing tool}
+\description{
+a data clearning, analysis and statistical modeling assessing tool.
+}
+
diff --git a/man/PopMiss.Rd b/man/PopMiss.Rd
index 16663d4..a10fce4 100644
--- a/man/PopMiss.Rd
+++ b/man/PopMiss.Rd
@@ -31,7 +31,7 @@ PopMiss(data,na.treatment=c("mean.or.mode","delete","replace"),replace=NULL)
 \method{PopMiss}{matrix}(data, na.treatment, replace)
 }
 \arguments{
-\item{data}{This could be data frame, matrix or a vector.}
+\item{data}{This could be data frame,data.table, matrix or a vector.}
 
 \item{na.treatment}{One of "mean.or.mode", "delete", or "replace", to specify the method to populate missing values.}
 
diff --git a/man/interPlot.Rd b/man/interPlot.Rd
new file mode 100644
index 0000000..0548bd8
--- /dev/null
+++ b/man/interPlot.Rd
@@ -0,0 +1,33 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/interPlot.R
+\name{interPlot}
+\alias{interPlot}
+\title{interPlot}
+\usage{
+interPlot(data,xvar,yvar,zvar)
+}
+\arguments{
+\item{data}{a data frame.}
+
+\item{xvar}{either an integer to specify the position of the variable in the data frame, or the name of the variable.}
+
+\item{yvar}{either an integer to specify the position of the variable in the data frame, or the name of the variable.}
+
+\item{zvar}{either an integer to specify the position of the variable in the data frame, or the name of the variable.}
+}
+\description{
+Interactive 3D plot by calling `plotly` package functions.
+}
+\details{
+This functions gives a 3D interactive view of between factors.
+This is really useful when modeller wants to assess the interaction terms.
+Hence the "zvar" can be actual response data or model predictions.
+}
+\examples{
+
+interPlot(mtcars,"wt","mpg","vs")
+}
+\author{
+Sixiang Hu
+}
+