CODEWITHSUNDEEP
rloopsdataframe
Cisco
Cisco

Reputation: 137

Subsetting among data.frame with a loop

I have a problem with a loop over different data.frames to select certain rows. Here is a simple example.

I have here three data.frames:

Died.At <- c(22,40,72,41)
Writer.At <- c(16, 18, 36, 36)
Sex <- c("MALE", "MALE", "MALE", "FEMALE")
europe<-data.frame(Died.At, Writer.At, First.Name, Second.Name, Sex)

Died.At <- c(22,40,72,41)
Writer.At <- c(50, 28, 46, 16)
Sex <- c("MALE", "MALE", "MALE", "FEMALE")
africa<-data.frame(Died.At, Writer.At, First.Name, Second.Name, Sex)

Died.At <- c(22,40,72,41)
Writer.At <- c(30, 18, 96, 66)
Sex <- c("MALE", "MALE", "MALE", "FEMALE")
asia<-data.frame(Died.At, Writer.At, First.Name, Second.Name, Sex)

I want to select the individuals with [Writer.At<=20] And I want to rewrite every database with just these individuals. So I tried this:

for (i in c(europe,africa,asia)){
  A.i<-i[i$Writer.At>=20]
}

What I get is this warning: Error in i$Writer.At: $ operator is invalid for atomic vectors

I don't understand why. Could you help me to solve this problem?

Upvotes: 0

Views: 38

Answers (1)

user3640617
user3640617

Reputation: 1576

Your solution doesn't work because "i" refers to values in each data frame, not the name of the data frame. One solution is like this:

for (i in c("europe","africa","asia")){
  df<-get(i)
  df<-df[df$Writer.At>=20,]
  assign(paste0("A",i), df)
}

Alternatively, you could combine the dataframes in a list and do the following:

writers <- list(europe=europe, africa=africa,asia=asia)
writersafter20 <- lapply(writers, subset, Writer.At>=20)

Upvotes: 1

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