Chapter 11 Trend of rankings of Serena Williams

plotTrendsRankings =  function(players_rankings,firstname,lastname,plottitle)
{
  players_rankings %>% 
    filter(first_name == firstname) %>%
    filter(last_name == lastname) %>%
    mutate(YearMonth = make_date(year=year,month=month) ) %>%
    
    ggplot(aes(x=YearMonth,y=ranking,group = 1)) +
    geom_point(size=2, color="red") +
    
    labs(x = 'Time', y = 'ranking',title = plottitle) +
    theme_bw() 
  
}

plotTrendsRankings(players_rankings,"Serena","Williams","Trend of Ranking for Serena Williams")

11.1 Rankings above 100

rankingsAboveThreshold = function(players_rankings,firstname,lastname,threshold)
{
  players_rankings %>% 
    filter(first_name == firstname) %>%
    filter(last_name == lastname) %>%
    filter(ranking >=threshold)
}

serena100 = rankingsAboveThreshold(players_rankings,"Serena","Williams",100) %>%
  select(year,month,ranking) %>% 
  arrange(desc(ranking))

kable(serena100,"html") %>%
  kable_styling(bootstrap_options = c("striped", "hover", "condensed", "responsive")) %>%
  scroll_box(width = "800px")

year	month	ranking
1997	10	453
1997	10	448
1997	11	304
2011	07	175
2011	07	172
2011	07	172
2011	07	169
2006	07	140
2006	07	139
2006	08	110
2006	05	108
2006	05	108
2006	06	108
2006	07	108
2006	07	108
2006	04	107
2006	04	107
2006	04	106
2006	05	106
2006	05	105
2006	05	105
2006	06	104
2006	06	104
2006	06	104
2006	07	104
1997	11	102
1997	12	101
1997	12	101
1998	01	101
1997	11	100

It is evident that Serena had rankings dropped past 50 and 100 in the years 2006 and 2011.