R中的多线图谱图不叠加

Question

我正在尝试在R中创建堆积线图。换句话说，我想要一年的时间序列图，其中包含多条线。但是，它总是作为一条线出现。这三行的数据日期确实不同。现在我可能正在关注xts变量，这可能与NA有关。

     sixteen <- pop %>% filter(between(Date, as.Date("2016-09-06"), as.Date("2016-12-30")))
 don16 <- xts(x = sixteen$sum, order.by = sixteen$Date)

 seventeen <- pop %>% filter(between(Date, as.Date("2017-01-01"), as.Date("2017-12-30")))
 don17 <- xts(x = seventeen$sum, order.by = seventeen$Date) 

 eighteen <- pop %>% filter(between(Date, as.Date("2018-01-01"), as.Date("2018-12-30")))
 don18 <- xts(x = eighteen$sum, order.by = eighteen$Date) 


 dondun <- cbind(don16 = as.xts(don16), don17 = as.xts(don17), don18 = as.xts(don18))

                            dygraph(dondun)  %>%
                              dyOptions(stackedGraph = TRUE) %>%
                              dyOptions(labelsUTC = TRUE, fillGraph=TRUE, fillAlpha=0.1, drawGrid = FALSE) %>%
                              dyRangeSelector() %>%
                              dyCrosshair(direction = "vertical") %>%
                              dyHighlight(highlightCircleSize = 5, highlightSeriesBackgroundAlpha = 0.2, hideOnMouseOut = FALSE)


                            })

有我的代码，数据集的前六行看起来像这样……

           don16 don17 don18
2016-09-06    94    NA    NA
2016-09-07    78    NA    NA
2016-09-08    55    NA    NA
2016-09-09    59    NA    NA
2016-09-12    60    NA    NA
2016-09-13    68    NA    NA