Major and minor tickmarks with plotly

Question

I would like to generate a figure in plotly like the following figure generated with the base R graphics:

The R code for the figure above is the following:

x = c(1,2,3,4,5)
y = c(0.1, 1, 10, 100, 1000)
axseq = y
plot(x, log10(y), yaxt="n")
axis(2, at=log10(axseq), labels=as.character(axseq))
for (i in 1:5){
    bb = 1:10; a = (bb*10^(i-2));   axis(2, at=log10(a), tcl=-0.25, labels=F)
}

My plotlycode for the same figure so far is the following:

p = plot_ly(x=x, y=log10(y), mode="markers") %>%
layout(yaxis = list(tickmode="array", tickvals=log10(axseq), ticktext=as.character(axseq), zeroline=F, showline=T, ticks="outside"),
       xaxis = list(showline=T, ticks="outside"))

it has the major ticks, but I can't find how to add the minor ticks on the y axis.

Answer 1

As you started to implement already, you can customize the ticks by specifying the values at which they are placed (with tickvals) and the labels (with ticktext). But you need to put a value for every tick location in tickvals, and every tickval needs a corresponding ticktext. So, the way to differentiate between major and minor ticks is by setting the ticktext to an empty string for all the minor ticks (because plotly doen't have a way to specify minor ticks per se).

tval <- sort(as.vector(sapply(seq(1,9), function(x) x*10^seq(-1,3)))) #generates a sequence of numbers in logarithmic divisions
ttxt <- rep("",length(tval))  # no label at most of the ticks
ttxt[seq(1,37,9)] <- as.character(tval)[seq(1,37,9)] # every 9th tick is labelled

p = plot_ly(x=x, y=y, mode="markers") %>%
  layout(yaxis = list(type="log",
                      zeroline=F, showline=T, 
                      ticks="outside",
                      tickvals=tval,
                      ticktext=ttxt),
         xaxis = list(showline=T, ticks="outside"))
p