Create a new column to a dataframe based on the values of another dataframe

Question

I have a dataframe like this:

name
Google
Amazon
Google
Yahoo
Google
Yahoo

And another one like this:

name   stock_name
Google  stockA
Amazon  stockB
Yahoo   stockC

The final result I would like to take from the merge of these 2 dataframes:

name stock_name
Google stockA
Amazon stockB
Google stockA
Yahoo  stockC
Google stockA
Yahoo  stockC

Using the merge it is not possible to make it. Any hind on how could make it?

Unless a valid reason is given, this is 100% duplicate of merge post: http://stackoverflow.com/questions/1299871 — zx8754, Mar 30 '17 at 20:45
Well, possibly left outer join depending on your ordering but yes. This is the most basic of merge operations. — MrFlick, Mar 30 '17 at 20:50

Mouad_Seridi · Accepted Answer · 2017-03-30T20:46:42.423

1

if you call your data frames df1 and df2 you could do

 df1$stock_name <- df2$stock_name[match(df1$name, df2$name)]

edited Mar 30 '17 at 20:46

answered Mar 30 '17 at 20:39

Mouad_Seridi

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score 0 · Answer 2 · answered Mar 30 '17 at 20:55

Another way to solve this:

df1 <- data.frame(data = c("Google", "Amazon", "Google", "Yahoo", "Google", "Yahoo"))

df2 <- data.frame(data = c("Google" = "stockA", "Amazon"  = "stockB", "Yahoo" = "stockC"))
colnames(df2) <- "stock_name"

df1$stock_name <- df2[df1$data, 1]

Create a new column to a dataframe based on the values of another dataframe

2 Answers2