I'm trying to plot several data series onto the same plot in R, but even with the showZeroValues=TRUE argument in dyLegend(), the legend stops showing values on mouseover when at least one of the series has a y=0 at the current x. I am not sure what I am doing wrong.
Below is a simplified example:
library(dygraphs)
library(xts)
x=data.frame(a=c(1, 2, 3, 1, 0, 0, 2), b=c(2, 3, 1, 0, 1, 4, 5))
x$Date=seq(as.Date("2017-06-01"), (as.Date("2017-06-01")+dim(x)[1]-1), by="days")
d=xts(x, order.by=x$Date)[,1:2]
dygraph(d) %>%
dyOptions(drawGrid=FALSE, fillGraph=TRUE) %>%
dyLegend(labelsSeparateLines=TRUE, showZeroValues=TRUE)
On my computer the dynamic legend skips all x values at which one of the two series has y=0, as can be seen with the cursor being close to zeros but the legend still stuck on the right end of the graph: example.
I had the same issue and found out that it was caused by the xts object containing character strings. The original data frame had a Date column, which I used to create the xts object, but I did not subset the numerical data. This resulted in the xts object being created but with character values (see issue here). Surprisingly enough, the resulting plots were not much impacted, and the output was correct, which made troubleshooting less straightforward.
In your example, the following should solve the issue:
x=data.frame(a=c(1, 2, 3, 1, 0, 0, 2), b=c(2, 3, 1, 0, 1, 4, 5))
x$Date=seq(as.Date("2017-06-01"), (as.Date("2017-06-01")+dim(x)[1]-1), by="days")
d=xts(x[, 1:2], order.by=x$Date) # This is the only change in your code
dygraph(d) %>%
dyOptions(drawGrid=FALSE, fillGraph=TRUE) %>%
dyLegend(labelsSeparateLines=TRUE, showZeroValues=TRUE)