基于R中的列比较两个数据帧

Question

I'm trying to find a way to program the following in R

I have a data frame in which I will be sorting the table based on the lowest growth rates for a set of companies

Table 1

Company  Growth-Dept1   
   A        5%   
   B        10%  
   C        15%  
   D        20%

Table 2

Company Growth-Dept2    
   A         2%  
   M         4%  
   D         8%  
   C         2%

I want to compare Table2 based on the Company names in Table1 and generate a Table3 that only has matching names

Output Table 3

Company  Growth-Dept2  
  A        2%  
  C        2%  
  D        8%

Will I need to use a loop in this case? Any other way to program this? I have around 800 entries in each column

Answer 1

How does this look?

t1 <- data.frame(company=c('A','B','C','D'),growth=c(.05,.1,.15,.2))
t2 <- data.frame(company=c('A','M','D','C'),growth=c(.02,.04,.08,.02))
tcombined <- t2[which(t1$company %in% t2$company),]
tcombined <- tcombined[order(tcombined$growth),]
tcombined

gives

  company growth
1       A   0.02
4       C   0.02
3       D   0.08

Answer 2

Using data.table along with scales for percentages.

library(data.table)
library(scales)

dt1 <- data.table(Company=c('A','B','C','D'),growth_dep1=percent(c(.05,.1,.15,.2)), key = "Company")
dt2 <- data.table(Company=c('A','M','D','C'),growth_dep2=percent(c(.02,.04,.08,.02)), key = "Company")

dt1[dt2][!is.na(growth_dep1), .(Company, growth_dep2)][order(growth_dep2)]