Setup/Config

Be sure you’ve completed the steps on the Initial Setup page before running this code.

For the setup, we’re going to load a few libraries, load our specific Google Analytics credentials, and then authorize with Google.

# Load the necessary libraries. These libraries aren't all necessarily required for every
# example, but, for simplicity's sake, we're going ahead and including them in every example.
# The "typical" way to load these is simply with "library([package name])." But, the handy
# thing about using the approach below -- which uses the pacman package -- is that it will
# check that each package exists and actually install any that are missing before loading
# the package.
if (!require("pacman")) install.packages("pacman")
pacman::p_load(googleAnalyticsR,  # How we actually get the Google Analytics data
               tidyverse,         # Includes dplyr, ggplot2, and others; very key!
               devtools,          # Generally handy
               googleVis,         # Useful for some of the visualizations
               scales)            # Useful for some number formatting in the visualizations

# Authorize GA. Depending on if you've done this already and a .ga-httr-oauth file has
# been saved or not, this may pop you over to a browser to authenticate.
ga_auth(token = ".ga-httr-oauth")

# Set the view ID and the date range. If you want to, you can swap out the Sys.getenv()
# call and just replace that with a hardcoded value for the view ID. And, the start 
# and end date are currently set to choose the last 30 days, but those can be 
# hardcoded as well.
view_id <- Sys.getenv("GA_VIEW_ID")
start_date <- Sys.Date() - 31        # 30 days back from yesterday
end_date <- Sys.Date() - 1           # Yesterday

If that all runs with just some messages but no errors, then you’re set for the next chunk of code: pulling the data.

Pull the Data

Now we’re ready to make our call to the google_analytics_4 function. We’ll pull the uniquePageViews metric, combined with the channelGrouping and secondPagePath (read about this metric in the GA reporting documentation).

Before making the call, we need to build a filter_clause_ga4 object, containing one dim_filter to get data only for sessions where our users landed on the homepage of our site. Mark Edmondson has written some very helpful documentation on the new filter clauses - read the documentation here.

The code below will build a list which can be passed as an argument to our google_analytics_4 request. We use a regular expression to identify the homepage. The code below assumes the homepage shows up in your Pages report as simply “/”, but you can adjust the expressions argument if that’s not actually the case (or, of course, you can run this entire example for any landing page you choose by adjusting that argument. Or… create multiple Sankey charts for each of your top landing pages; oh…the possibilities!) .

# Create page filter object
page_filter <- dim_filter(
  dimension = "landingPagePath",
  operator = "REGEXP",
  expressions = "^/$")
homepage_filter <- filter_clause_ga4(list(page_filter))

# Now, we're ready to pull the data from the GA API. We build a `google_analytics_4` request, 
# passing the `homepage_filter` to the `dim_filters` argument.
home_next_pages <- google_analytics(
  viewId = view_id,
  date_range = c(start_date, end_date),
  dimensions = c("secondPagePath", "channelGrouping"),
  metrics = "uniquePageviews",
  dim_filters = homepage_filter,
  max = -1,
  anti_sample = TRUE
)

# Go ahead and do a quick inspection of the data that was returned. This isn't required,
# but it's a good check along the way.
head(home_next_pages)

What we have is a data frame containing unique pageviews per next page for visits which started on your homepage, split by traffic source. The data used here isn’t from a site with the world’s most diverse and interesting set of channels, but, with luck, your data will be!

Data Munging

We have a small problem in the number of possible next pages for our sessions (you don’t need to include this code – it’s just checking the number of unique values for the secondPagePath dimension in our data set).

length(unique(home_next_pages$secondPagePath))

## [1] 25

We should thin this down to a number which can be easily visualised, which is a two-step process:

1. We’ll group the data by page path, arrange in order of pageviews and filter out the lower-volumes pages (or, put another way, only keep the top 10 pages overall).
2. We’ll then go back to our original data set and keep only the values that include those top 10 pages.

# Build the data frame of top 10 pages:
top_10 <- home_next_pages %>% 
  group_by(secondPagePath) %>% 
  summarise(upvs = sum(uniquePageviews)) %>% 
  top_n(10, upvs) %>% 
  arrange(desc(upvs))

# Using this list of our top 10 pages, use the `semi_join` function from `dplyr` to restrict 
# our data to pages & channels that have one of these top 10 pages as the second page viewed.
home_next_pages <- home_next_pages %>% 
  semi_join(top_10, by = "secondPagePath")

# Check the data again. It's the same structure as it was originally, and the head() is likely
# identical. But, we know that, deeper in the data, the lower-volume pages have been removed.
head(home_next_pages)

Now we have a data frame ready for plotting, using our top 10 pages. Again, you don’t need to include this code. We’re just showing that we’re now down to 10 unique values for secondPagePath.

# Only 10 unique URLs are in our results, now
length(unique(home_next_pages$secondPagePath))

## [1] 10

Data Visualization

# Reordering colums: the gVisSankey function doesn't take kindly
# if our df columns aren't strictly ordered as from:to:weight
home_next_pages <- home_next_pages %>% 
  select(channelGrouping, secondPagePath, uniquePageviews)

# Build the plot
s <- gvisSankey(home_next_pages)
                # chartid = chart_id)
plot(s)

# 8 values from colorbrewer. Note the use of array notation
# colour_opts <- '["#7fc97f", "#beaed4","#fdc086","#ffff99","#386cb0","#f0027f","#bf5b17","#666666"]'
colour_opts <- '["#7fc97f", "#beaed4","#fdc086","#ffff99"]'

# Set colorMode to 'source' to colour by the chart's source
opts <- paste0("{
        link: { colorMode: 'source',
                colors: ", colour_opts ," }
      }" )

# This colour list can now be passed as an option to our `gvisSankey` call. We pass them to the 
# `options` argument for our plot.
s <- gvisSankey(home_next_pages,
                options = list(sankey = opts))
plot(s)

# 25% gray for all sources except the second one.
colour_opts <- '["#999999", "#7fc97f","#999999","#999999","#999999","#999999","#999999","#999999"]'

opts <- paste0("{
        link: { colorMode: 'source',
                colors: ", colour_opts ," },
        node: { colors: '#999999' }
      }" )

# This colour list can now be passed as an option to our `gvisSankey` call.
s <- gvisSankey(home_next_pages,
                options = list(sankey = opts))
plot(s)