1. use mids not breaks in echart_hist()

2. simple functions for add line and points to plot. Not tested yet.
3. start to wrap an eSeries function to add Series attributes.

R/add_line.R

@@ -0,0 +1,61 @@
+echart_stat_line = function ( stat, name = NULL){
+  # stat is the statisitic of such hline,
+  check_stat(stat)
+  if (length(stat) > 1) stop("Only one stat each time.")
+  list(markLine= list(data = list(type = stat, name = name )))
+}
+
+# a more general function to add any line
+echart_abline_point = function ( start, end, name = NULL){
+  # start is a vector with two values (x,y)
+  # end is a vector with two values (x,y)
+  if (!is.numeric(start) | !is.numeric(end)) stop("start and end should be numeric vectors.")
+  if (length(start)!=2 | length(end) != 2) stop("start and end should be a vector of two numeric values.")
+  if (Inf %in% c(start, end)) {
+    warning("Cannot draw infinitie line.") # check if echart can handle Inf; if not, replace Inf
+
+    }
+  list(markLine =
+         list(data =
+                c(list( name = 'line start', value = 1, x = start[1], y = start[2]),
+                               list( name = 'line end',  x = end[1], y = end[2]))
+                      ))
+
+}
+
+# wrap of abline(); add line by intercept and slope
+echart_abline = function ( intercept, slope, name = NULL,
+                                 # put some defaults here, could be extended
+                                 xmin = -100,
+                                 xmax = 100,
+                                 ymin = -100,
+                                 ymax = 100){
+  # start is a vector with two values (x,y)
+  # end is a vector with two values (x,y)
+  y_min_actual = xmin * slope + intercept
+  y_max_actual = xmax * slope + intercept
+
+  start = c(xmin, y_min_actual)
+  end = c(xmax, y_max_actual)
+
+  # ignore ymin and ymax for now
+  echart_abline_point(start, end, name = name)
+}
+
+# wrap function for horizontal line
+echart_hline = function (yintercept, name = NULL){
+  if (!is.numeric(y)) stop("yintercept must be numeric.")
+  if (length(yintercept)>1) stop("only one line each time.")
+  echart_abline(intercept = yintercept, slope = 0)
+}
+
+# wrap function for vertical line
+
+echart_vline = function (xintercept, name = NULL){
+  if (!is.numeric(y)) stop("yintercept must be numeric.")
+  if (length(xintercept)>1) stop ("one line each time.")
+  start = c(xintercept, -Inf)
+  end = c(xintercept, Inf)
+  echart_abline_point(start, end, name = name)
+}
+

R/add_point.R

@@ -0,0 +1,18 @@
+# function to add points on plot
+echart_point = function (x, y, name = NULL, value = NULL){
+  if (!is.numeric(x) | !is.numeric(y)) { stop("x and y should be numeric.")}
+  list(markPoint = list(data = list(name = name, value =  value, x = x, y = y)))
+}
+
+# add statistic point directly
+echart_stat_point = function (stat, name = NULL, value = NULL){
+  check_stat(stat)
+  list(markPoint = list(data = list(name = name, type = stat)))
+}
+
+check_stat = function (stat){
+  if (!stat %in% c("min","max","average")){
+    stop("stat should be either min, max or avergae.")
+  }
+}
+

R/echart.R

@@ -67,10 +67,6 @@ echart.data.frame = function(
     params$legend = list(data = levels(as.factor(series)))
   }
 
-  if("barCategoryGap" %in% names(list(...))){
-    for (i in 1:length(params$series))
-    {params$series[[i]]$barCategoryGap = list(...)$barCategoryGap}
-  }
 
   chart = htmlwidgets::createWidget(
     'echarts', params, width = width, height = height, package = 'recharts',

R/echart_hist.R

@@ -17,6 +17,8 @@ echart_hist = function(data, binwidth = NULL){
   } else{
     bar_hist = hist(data, plot = FALSE , binwidth = binwidth)
   }
+  # adjust the breaks
+  # bar_hist$x = round(bar_hist$mids,2)
 
-  echart(bar_hist, ~breaks, ~counts,  type ="bar", barCategoryGap='0%')
+  echart(bar_hist, ~mids, ~counts,  type ="bar", barCategoryGap='0%')
 }

R/options.R

@@ -67,3 +67,9 @@ axisType = function(data, which = c('x', 'y')) {
   str(data)
   stop('Unable to derive the axis type automatically from the ', which, ' variable')
 }
+
+eSeries = function (chart,barCategoryGap, ...){
+    # basically we need to add barCategoryGap to series
+    params$series[[i]]$barCategoryGap = list(...)$barCategoryGap
+
+}