I have a complicated question that I will try to simplify by simplifying my dataset. Say I have 5 variables:
我有一个复杂的问题，我将通过简化我的数据集来尝试简化。说我有5个变量：
df$Id <- c(1:12)
df$Date <- c(NA,NA,a,a,b,NA,NA,b,c,c,b,a)
df$va <- c(1.1, 1.4, 2.5, ...) #12 randoms values
df$vb <- c(5.9, 2.3, 4.7, ...) #12 other random values
df$vc <- c(3.0, 3.3, 3.7, ...) #12 more random values
Then I want to create a new variable that takes the value from va, vb, or vc if the date is equal to a, b, or c. I had tried a nested if-else, which did not work. I also tried:
然后我想创建一个新变量，如果日期等于a，b或c，则从va，vb或vc获取值。我曾尝试过嵌套的if-else，但是没有用。我也尝试过：
df$new[df$date=='a' & !is.na(df$date)] <- df$va
df$new[df$date=='b' & !is.na(df$date)] <- df$vb
df$new[df$date=='c' & !is.na(df$date)] <- df$vc
This correctly left NA's in the new variable where Date=NA, however the values provided were not from va, vb, or vc, but some other value altogether. How can I get df$new to equal va if the date is 'a', vb if the date is 'b', and vc if the date is 'c'?
这正确地将NA保留在新变量中，其中Date = NA，但是提供的值不是来自va，vb或vc，而是来自其他一些值。如果日期为'a'，如果日期为'b'，如果日期为'c'，则如何获得等于va的df $ new;如果日期为'c'，则为vc？
1 个解决方案
#1
1
You want the ifelse function, which is a vectorized conditional:
你想要ifelse函数，它是一个矢量化条件：
> x <- c(1, 1, 0, 0, 1)
> y <- c(1, 2, 3, 4, 5)
> z <- c(6, 7, 8, 9, 10)
> ifelse(x == 1, y, z)
[1] 1 2 8 9 5
You will have to nest calls to this function, like this:
您必须嵌套对此函数的调用，如下所示：
> x_1 <- c(1, 1, 0, 0, 1)
> x_2 <- c(1, 1, 1, 0, 1)
> y_1 <- c(1, 2, 3, 4, 5)
> y_2 <- c(6, 7, 8, 9, 10)
> z <- c(0, 0, 0, 0, 0)
> ifelse(x_1 == 1, y_1,
+ ifelse(x_2 == 1, y_2, z)
+ )
[1] 1 2 8 0 5
Your second attempt would succeed if you made the following modification:
如果您进行了以下修改，您的第二次尝试将成功：
df$new[df$date=='a' & !is.na(df$date)] <- df$va[df$date=='a' & !is.na(df$date)]
To avoid the new variable becoming a list rather than a numeric variable, use %in% in place of ==:
要避免新变量成为列表而不是数字变量，请使用％in％代替==：
df$new[df$date %in% 'a' & !is.na(df$date)] <- df$va[df$date %in% 'a' & !is.na(df$date)]
#1
1
You want the ifelse function, which is a vectorized conditional:
你想要ifelse函数，它是一个矢量化条件：
> x <- c(1, 1, 0, 0, 1)
> y <- c(1, 2, 3, 4, 5)
> z <- c(6, 7, 8, 9, 10)
> ifelse(x == 1, y, z)
[1] 1 2 8 9 5
You will have to nest calls to this function, like this:
您必须嵌套对此函数的调用，如下所示：
> x_1 <- c(1, 1, 0, 0, 1)
> x_2 <- c(1, 1, 1, 0, 1)
> y_1 <- c(1, 2, 3, 4, 5)
> y_2 <- c(6, 7, 8, 9, 10)
> z <- c(0, 0, 0, 0, 0)
> ifelse(x_1 == 1, y_1,
+ ifelse(x_2 == 1, y_2, z)
+ )
[1] 1 2 8 0 5
Your second attempt would succeed if you made the following modification:
如果您进行了以下修改，您的第二次尝试将成功：
df$new[df$date=='a' & !is.na(df$date)] <- df$va[df$date=='a' & !is.na(df$date)]
To avoid the new variable becoming a list rather than a numeric variable, use %in% in place of ==:
要避免新变量成为列表而不是数字变量，请使用％in％代替==：
df$new[df$date %in% 'a' & !is.na(df$date)] <- df$va[df$date %in% 'a' & !is.na(df$date)]