2020-03-30-Homework-4

Explain series of "dplyr::*_join" results output

讀取資料，依年份排序

library(dplyr)

## 
## Attaching package: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

country.1 <- read.table("C:/Users/X510/Desktop/table/nobel_countries.txt", header = T)
winner.1 <- read.table("C:/Users/X510/Desktop/table/nobel_winners.txt", header = T)
country <- country.1[order(country.1$Year, decreasing = F),]
winner <- winner.1[order(winner.1$Year, decreasing = F),]

Merge data

無論是否有NA ，都列出來

dta <- merge(country, winner, all = TRUE)
dta

##   Year Country              Name Gender
## 1 1938    <NA>        Pearl Buck Female
## 2 1950      UK Bertrand  Russell   Male
## 3 2011  Sweden              <NA>   <NA>
## 4 2012   China            Mo Yan   Male
## 5 2013  Canada      Alice  Munro Female
## 6 2014  France   Patrick Modiano   Male
## 7 2015  Russia              <NA>   <NA>
## 8 2016      US        Bob  Dylan   Male
## 9 2017      UK    Kazuo Ishiguro   Male

inner_join函數

只保留“country, winner”共同年份的資料

country %>% inner_join(winner, by = "Year")

##   Country Year              Name Gender
## 1      UK 1950 Bertrand  Russell   Male
## 2   China 2012            Mo Yan   Male
## 3  Canada 2013      Alice  Munro Female
## 4  France 2014   Patrick Modiano   Male
## 5      US 2016        Bob  Dylan   Male
## 6      UK 2017    Kazuo Ishiguro   Male

semi_join函數

保留country的變項，並從與winner共同的年份進行篩選

country %>% semi_join(winner, by = "Year")

##   Country Year
## 1      UK 1950
## 2   China 2012
## 3  Canada 2013
## 4  France 2014
## 5      US 2016
## 6      UK 2017

left-join函數

保留country的變項，並融入與winner年分共有的資料

country %>% left_join(winner, by = "Year")

##   Country Year              Name Gender
## 1      UK 1950 Bertrand  Russell   Male
## 2  Sweden 2011              <NA>   <NA>
## 3   China 2012            Mo Yan   Male
## 4  Canada 2013      Alice  Munro Female
## 5  France 2014   Patrick Modiano   Male
## 6  Russia 2015              <NA>   <NA>
## 7      US 2016        Bob  Dylan   Male
## 8      UK 2017    Kazuo Ishiguro   Male

anti-join函數

丟棄country, winner共有的資料

country %>% anti_join(winner, by = "Year")

##   Country Year
## 1  Sweden 2011
## 2  Russia 2015

full-join函數

保留所有的資料

country %>% full_join(winner, by = "Year")

##   Country Year              Name Gender
## 1      UK 1950 Bertrand  Russell   Male
## 2  Sweden 2011              <NA>   <NA>
## 3   China 2012            Mo Yan   Male
## 4  Canada 2013      Alice  Munro Female
## 5  France 2014   Patrick Modiano   Male
## 6  Russia 2015              <NA>   <NA>
## 7      US 2016        Bob  Dylan   Male
## 8      UK 2017    Kazuo Ishiguro   Male
## 9    <NA> 1938        Pearl Buck Female