在 R 中计算多个变量

Question

我有一系列反应时间：从 trail1 到 trail100，然后是 answer1 到 answer100。

我想要在 R 中计算的新变量：如果 trail1 的值是 1 到 15，那么对应的 answer1 应该是 answer1 的值。 如果 trial1 为 0，则对应的 answer1 应为 -1

ID <- c("1", "2", "3")
Trial1 <- c("3", "0", "8")
Trial2 <- c("5", "6", "15")
Trial3 <- c("14", "15", "10")
Answer1 <- c("489", "368", "-1")
Answer2 <- c("363", "967", "671")
Answer3 <- c("700", "1201", "890")

df <- data.frame(ID, Trial1, Trial2, Trial3, Answer1, Answer2, Answer3)

正确的新变量（new_answer1 到 100）应该是：

ID <- c("1", "2", "3")
Trial1 <- c("3", "0", "8")
Trial2 <- c("5", "6", "15")
Trial3 <- c("14", "15", "10")
New_Answer1 <- c("489", "-1", "-1")
New_Answer2 <- c("363", "967", "671")
New_Answer3 <- c("700", "1201", "890")

df1 <- data.frame(ID, Trial1, Trial2, Trial3, New_Answer1, New_Answer2, New_Answer3)

谢谢

Answer 1

如果我理解正确，则需要一个简单的表达式：

New_Answer1 <- Answer1
New_Answer1[Trial1==0] <- -1

出去：

> New_Answer1
[1] "489" "-1"  "-1"