Filter rows that contain values from a list

user_19045342 0
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I'm using RStudio, and I have one dataframe containing a list of candidates, and a dataframe containing all votes of each voting location, and by candidate.

I want to extract only the rows containing the votes of the candidates of this list.

Example:

  • List:

     Candidate
 A
 B
 D
 G

  • Votes:

     Candidate       Number of Votes
 A               124
 B               52
 C               13
 D               62
 E               33
 F               7
 G               67

I want then to create a new dataframe containing only the candidates and votes of the "List":

  • Votes of listed candidates:

     Candidate       Number of Votes
 A               124
 B               52
 D               62
 G               67

The example is a simplification. My database contains over 30.000 "candidates"

Thanks in advance

dplyr dataframe r
2 Answers

We can use subset in base R

subset(Votes, Candidate %in% List$Candidate)
user_37322710

You can merge both data frames with merge():

merge(df1, df2, by = "Candidate", all.x = TRUE)

or equivalently

dplyr::left_join(df1, df2, by = "Candidate")

#   Candidate Number_of_Votes
# 1         A             124
# 2         B              52
# 3         D              62
# 4         G              67
Data
df1 <- structure(list(Candidate = c("A", "B", "D", "G")), class = "data.frame", row.names = c(NA, -4L))
df2 <- structure(list(Candidate = c("A", "B", "C", "D", "E", "F", "G"),
Number_of_Votes = c(124L, 52L, 13L, 62L, 33L, 7L, 67L)), class = "data.frame", row.names = c(NA, -7L))
user_100689850
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