How to run a changepoint analysis on multiple time series with dplyr

Question

I'm collecting time series data from Wikipedia and want to run a change-point analysis on each time series using dplyr. But when I do so I get an error saying the data need to be numeric, even though the class function states it is numeric. Hope you can help.

library(changepoint)
library(dplyr)
library(pageviews)
library(data.table)

articles <- c("Rugby_union", "Football")

foo <- function(x){article_pageviews(project = "en.wikipedia",
                                     article = x, 
            start = as.Date('2017-01-01'), 
            end = as.Date("2017-12-31")
          , user_type = "user", platform = c("mobile-web"))
    }

output<-articles %>% foo

output %>% 
  select(article, views) %>% 
  do(cpt.mean(.)) 

class(output$views)

Answer 1

library(changepoint)
library(dplyr)
library(pageviews)

articles <- c("Rugby_union", "Football")

foo <- function(x){article_pageviews(project = "en.wikipedia", article = x, 
                                     start = as.Date('2017-01-01'), 
                                     end = as.Date("2017-12-31"),
                                     user_type = "user", platform = c("mobile-web"))
}

output <- articles %>% 
  foo
df <- as.data.frame(table(output$article))
output1 <- output %>% 
  dplyr::select(article, views) %>% 
  dplyr::filter(article == df[1,1])
output2 <- output %>% 
  dplyr::select(article, views) %>% 
  dplyr::filter(article == df[2,1])
q <- floor((min(length(output1$views), length(output2$views)))/2 + 1)
cp1 <- changepoint::cpt.mean(data = output1$views, Q = q, method = "BinSeg", penalty 
= "SIC")
plot(cp1)

cp2 <- changepoint::cpt.mean(data = output2$views, Q = q, method = "BinSeg", penalty 
= "SIC")
plot(cp2)