Add elements to existing plotly plot in R - r

Question

I'm just starting to use plotly and I haven't been able to do something as simple as adding objects to an existing plot. How can I add line segments to an existing empty plot?
I've tried this, but every call of add_segment creates a new plot with only one segment:
p<-plot_ly()
add_segment(p,x=0,y=1,x=5,y=1)
add_segment(p,x=0,y=4,x=5,y=4)
What am I doing wrong?

Answer 1

The answer: use the %>% operator like this:
p <- plot_ly(data, x = ~x)
p <- p %>% add_trace(y = ~trace_0, name = 'trace 0',mode = 'lines')
p
The details:
One approach is to use the piping %>% operator from this example where the following plot is produced by the code below:
Plot:
Code:
library(plotly)
set.seed(1)
trace_0 <- rnorm(100, mean = 5)
trace_1 <- rnorm(100, mean = 0)
trace_2 <- rnorm(100, mean = -5)
x <- c(1:100)
data <- data.frame(x, trace_0, trace_1, trace_2)
p <- plot_ly(data, x = ~x) %>%
add_trace(y = ~trace_0, name = 'trace 0',mode = 'lines') %>%
add_trace(y = ~trace_1, name = 'trace 1', mode = 'lines+markers') %>%
add_trace(y = ~trace_2, name = 'trace 2', mode = 'markers')
p
Step by step using %>%:
Code Step 1:
# step 1
p <- plot_ly(data, x = ~x)
# plot
p
Plot step 1:
Code step 2:
# step 1
p <- plot_ly(data, x = ~x)
# step 2
p <- p %>% add_trace(y = ~trace_0, name = 'trace 0',mode = 'lines')
# plot
p
Plot step 2:
Code all steps:
# step 1
p <- plot_ly(data, x = ~x)
# step 2
p <- p %>% add_trace(y = ~trace_0, name = 'trace 0',mode = 'lines')
# step 3
p <- p %>% add_trace(y = ~trace_1, name = 'trace 1', mode = 'lines+markers')
# step 4
p <- p %>% add_trace(y = ~trace_2, name = 'trace 2', mode = 'markers')
# plot
p
Plot all steps:
Edit: Response to comments
Is there any way to add elements without using the pipe?
Not to my knowledge, but I'm hoping someone proves me wrong. Since this is an [R] question, I'm guessing you're more familiar with building ggplot plots stepwise like this:
library(ggplot2)
g <- ggplot(diamonds, aes(x=carat, y=price, color=cut)) + geom_point()
g <- g + geom_smooth()
g
The + approach will not work for plotly though:
Code:
# step 1
p <- plot_ly(data, x = ~x)
# step 2
p <- p + add_trace(y = ~trace_0, name = 'trace 0',mode = 'lines')
Error:
Error in add_data(p, data) : argument "p" is missing, with no default
And there's absolutely no reason to fear the %>% operator. a %>% b simply means something along the lines of Take a, and do b with it. To my knowledge, this was first seen in the magrittr package, and is widely used in the fantastic dplyr package. I'm mostly messing around with python at the time, but this really makes me miss R