CODEWITHSUNDEEP
rstringfor-loopindexing
Randomcloud
Randomcloud

Reputation: 61

For loop with an index inside a string in R

I have a rather simple problem but somehow I cannot solve it.

So I have a dataset with a column cycle with rows cycle1, cycle2, cycle3. I want to replace e.g. the word cycle1 with just the number 1. How to somehow separate the index i from the string cycle? 

for (i in 1:3){
   data$cycle[data$cycle=="cyclei"]<-i
}

Upvotes: 1

Views: 567

Answers (2)

Cristian E. Nuno
Cristian E. Nuno

Reputation: 2920

Use gsub()

# load data 
df <- data.frame( cycle = c( "cycle1", "cycle2", "cycle3" ), stringsAsFactors = FALSE )

# Identify the pattern and replace with nothing
# and cast the values as numeric
df$cycle <- as.numeric( gsub( pattern = "cycle", replacement = "", x = df$cycle ) )

# view results
df
#  cycle
# 1    1
# 2    2
# 3    3

# end of script #

Upvotes: 2

G. Grothendieck
G. Grothendieck

Reputation: 269596

Replace "cycle" with the empty string and convert to numeric:

data <- data.frame(cycle = c("cycle2", "cycle1", "cycle3")) # sample input

transform(data, cycle = as.numeric(sub("cycle", "", cycle)))

giving:

  cycle
1     2
2     1
3     3

Upvotes: 2

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