这可能是一个非常基本的问题,但似乎我很难理解 R 中的点 (.)。在下面的示例中,我使用rowSums
了两列的总和。但我不明白 rowSums 中点的作用。有人可以帮我理解这一点吗?
df1 <- data.frame(fruits = c("Apple", "Apple","Apple", "Mango", "Mango", "Kiwi", "Kiwi"),
prices1 = c(10, NA, NA, 15, NA, 20, NA), prices2 = c(NA, 12, NA, NA, 17, NA, 22),
prices3 = c(NA, NA, 14, NA, 21, NA, 25),
weights = c(20, 20, 20, 25, 25, 30, 30),
quality = c("Good", "Good", "Good", "Better", "Better", "Best", "Best"))
df1 %>% replace(is.na(.), 0) %>% mutate(sum = rowSums(.[2:3]))