If statements based on another column within a dataframe: in R -

for simple dataframe:

df <- structure(list(id = 1:9, sex = structure(c(2l, 2l, 1l, 2l, 1l,                                                1l, 2l, 2l, 1l), .label = c("f", "m"), class = "factor"), score = c(55l,                                                                                                                    60l, 62l, 47l, 45l, 52l, 41l, 46l, 57l)), .names = c("id", "sex",                                                                                                                                                                         "score"), class = "data.frame", row.names = c(na, -9l)) 

i want write if statements based on score males , females. basic if function go this:

df$score3<-ifelse(df$score <45,"low",                               ifelse(df$score>=45 & df$score<55,"normal",                                 ifelse(df$score >=55,"high", na))) 

how change expression males (separate cut offs used females (say low = <50, normal = >=50 & <58, high = >=58)).

if advice given on using if statements based on column within dataframe, grateful.

use data structure represent criteria

criteria<-list(m=c(0,50,58),f=c(0,45,55)) labels<-c("low","normal","high") grade<-function(score,sex) labels[findinterval(score,criteria[[sex]])]  df$grade<-mapply(grade,df$score,as.character(df$sex)) 

   id sex score  grade 1  1   m    55 normal 2  2   m    60   high 3  3   f    62   high 4  4   m    47    low 5  5   f    45 normal 6  6   f    52 normal 7  7   m    41    low 8  8   m    46    low 9  9   f    57   high