Update a Value in One Column Based on Criteria in Other Columns
df <- data.frame(Name=c('John Smith', 'John Smith', 'Jeff Smith'),
State=c('MI','WI','WI'), stringsAsFactors=F)
df <- within(df, Name[Name == 'John Smith' & State == 'WI'] <- 'John Smith1')
> df
Name State
1 John Smith MI
2 John Smith1 WI
3 Jeff Smith WI
** Edit **
Edited to add that you can put whatever you like in the within expression:
df <- within(df, {
f <- Name == 'John Smith' & State == 'WI'
Name[f] <- 'John Smith1'
State[f] <- 'CA'
})
One way:
df[df$Name == "John_Smith" & df$State == "WI", "Name"] <- "John_Smith1"
Another way using the dplyr
:
df %>% mutate(Name = ifelse(State == "WI" & Name == "John_Smith", "John_Smith1", Name))
Note: As David Arenburg says, the first column should not be a factor. For this, reading the data set stringsAsFactors = FALSE
.