Joining 2 tables together based on certain columns in r [duplicate] - r

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Closed 2 years ago.
I have two tables. The columns i am interested in table 1 is "Year" and "CompanyName". Table 2 has 3 columns including: "Year" and "CompanyName".
How can I join these two tables together? The problem I have is that table 1 has many columns that have for example the year value as "Year" = "2004" and "CompanyName" = "Adidas". e.g.
# There are many other columns
Year CompanyName Spent
1 2004 Adidas 50
2 2004 Nike 34
3 2004 Adidas 45
4 2005 Reebok 33
5 2006 Reebok 11
6 2006 Adidas 47
7 2007 Nike 33
8 2007 Reebok 92
9 2007 Nike 01
10 2007 Adidas 23
#I want to join this to it
Year CompanyName Loss
1 2004 Nike 23
2 2004 Adidas 22
3 2005 Reebok 633
4 2006 Reebok 2
5 2006 Adidas 09
6 2007 Reebok 22
7 2007 Nike 34
I want to join the tables so when ever Year is 2004 and CompanyName is Adidas a column is added for Loss with the value 23
Thank You!

Answer 1

You can do that by
library(dplyr)
df3 <- df1 %>%
left_join(df2, by = c("Year", "CompanyName"))
Just make sure you don't have duplications in df2 when it comes to year & company name. You can do so through dplyr::distinct(df2, Year, CompanyName, .keep_all = T), however that might lead to dropping some relevant information. If you're not certain about it, it might make sense to aggregate by those two dimensions:
df2 %>%
group_by(Year, CompanyName) %>%
summarise(Loss = sum(Loss))