矢量表是指两个因素

Question

我正在学习R,我向你保证我已经高低搜索了这个答案.这很简单,但出于某种原因,我无法理解我的生活!

我有一个包含一个数字向量和两个因素的数据框:

team.weight <- c(150,160,120,100) # player's weight
team.jersey <- factor(c("blue", "green", "blue", "blue")) # player's jersey color
team.sex <- factor(c("male", "female", "female", "male")) # player's sex
team <- data.frame(team.jersey, team.sex, team.weight)

我想显示一个表(我忘记它叫什么),显示所有玩家的平均权重,即平均值(team.weight),用于两个因子表的每个级别组合.

我可以手动完成,但必须有更好的方法!

mean(team.weight[c(team.jersey[1],team.sex[1])])
mean(team.weight[c(team.jersey[1],team.sex[2])])
mean(team.weight[c(team.jersey[1],team.sex[3])])
mean(team.weight[c(team.jersey[1],team.sex[4])])

mean(team.weight[c(team.jersey[2],team.sex[1])])
mean(team.weight[c(team.jersey[2],team.sex[2])])
mean(team.weight[c(team.jersey[2],team.sex[3])])
mean(team.weight[c(team.jersey[2],team.sex[4])])

mean(team.weight[c(team.jersey[3],team.sex[1])])
mean(team.weight[c(team.jersey[3],team.sex[2])])
mean(team.weight[c(team.jersey[3],team.sex[3])])
mean(team.weight[c(team.jersey[3],team.sex[4])])

mean(team.weight[c(team.jersey[4],team.sex[1])])
mean(team.weight[c(team.jersey[4],team.sex[2])])
mean(team.weight[c(team.jersey[4],team.sex[3])])
mean(team.weight[c(team.jersey[4],team.sex[4])])

任何帮助将不胜感激.我知道答案是愚蠢的,但我无法理解它是什么.

Answer 1

tapply(team.weight, list(team$team.jersey, team$team.sex), mean)
#       female male
# blue     120  125
# green    160   NA