Create group_by data frame using dplyr; use grid to show 2 plots in the same figure

dplyr_to_group_by_ggplot.r

suppressMessages(library(dplyr))
library(gridExtra)

pf <- read.delim("https://s3.amazonaws.com/udacity-hosted-downloads/ud651/pseudo_facebook.tsv")

pf.fc_by_age_months <- pf %>%
  group_by(age_with_months) %>%
  summarise(
    friend_count_mean=mean(friend_count),
    friend_count_median=median(friend_count),
    n=n()
  )
p1 <- ggplot(data=pf.fc_by_age_months, aes(x=age_with_months, y=friend_count_mean))+
  geom_line()+
  geom_smooth()

p2 <- ggplot(data=pf, aes(x=age, y=friend_count))+
  geom_line(stat='summary',fun.y=mean)+
  ylab("Friend Count Mean")

grid.arrange(p1,p2)