How to change the value of a variable using R programming in a data frame

Question

I am new to R programming and I have imported a CSV file. I would like to change the variable value for symbol column. If the value is "DEF" then "NEW1". If the value is "GHI" then "NEW2". I tried the below code but, I am getting a warning message and I checked the dataframe contains "NA" after changing.

df$symbol[df$symbol == "DEF"] <- "NEW1"
df$symbol[df$symbol == "GHI"] <- "NEW2"

Warning message:
In `[<-.factor`(`*tmp*`, df$symbol == "DEF",  :
  invalid factor level, NA generated

Answer 1

Try this:

df$symbol <- as.character(df$symbol)
df$symbol[df$symbol == "DEF"] <-"NEW1"

Answer 2

You are getting this error since the fields are saved as factors in the r data frame, so either convert like @Tyrion anex said after storing the data frame or while fetching the CSV into data frame by using stringsAsFactors = FALSE like below.

ABC = read.csv("C:\\Users\\Cherukuri_Sindhu\\Downloads\\abc.csv",stringsAsFactors = FALSE)

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Answer 3

Here you go, try this:

df$symbol <- as.character(df$symbol)
df$symbol[df$symbol == "ABCD.BO"] <-"Stock_T"