I think we need to see some sample data.
A handy way to supply some sample data is the dput() function. In the case of a large dataset something like dput(head(mydata, 100)) should supply the data we need. Just do dput(mydata) where mydata is your data. Copy the output and paste it here between
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Here is an example of the code working. Does this code work for you?
dat1 <- data.frame(notas = c(8,6,9,10,3,7,4))
#Añadimos una columna 'aprobado' a dat1
dat1$aprobado <- 0
#Analizamos las filas de dat1
for(i in 1:nrow(dat1)) {
#Si la nota del alumno es mayor o igual a 5, cambiamos el valor de 'aprobado' a 1
if(dat1$notas[i] >= 5){
dat1$aprobado[i] <- 1
}
}
#Mostramos las primeras filas de dat1 para comprobar el resultado
head(dat1)
#> notas aprobado
#> 1 8 1
#> 2 6 1
#> 3 9 1
#> 4 10 1
#> 5 3 0
#> 6 7 1