问题描述
我在R中有一个数据帧,如下所示:
I have a dataframe in R that looks like the following:
a b c condition
1 4 2 acap
2 3 1 acap
2 4 3 acap
5 6 8 ncap
5 7 6 ncap
8 7 6 ncap
我试图重新记录条件ncap(以及此处未显示的其他两个条件)的a,b和c列中的值,同时保留这些值独自一人。
I am trying to recode the values in columns a, b, and c for condition ncap (and also 2 other conditions not pictured here) while leaving the values for acap alone.
以下代码适用于前3列。我试图弄清楚如何将其仅应用于按条件指定的行,同时将所有内容保留在同一数据框中。
The following code works when applied to the first 3 columns. I am trying to figure out how I can apply this only to rows that I specify by condition while keeping everything in the same dataframe.
df = df %>%
mutate_at(vars(a:c), function(x)
case_when x == 5 ~ 1, x == 6 ~ 2, x == 7 ~ 3, x == 8 ~ 4)
这是预期的输出。
a b c condition
1 4 2 acap
2 3 1 acap
2 4 3 acap
1 2 4 ncap
1 3 2 ncap
4 3 2 ncap
我一直在寻找这个问题的答案,但找不到。如果有人知道已经存在一个答案,我将不胜感激。
I've looked around for an answer to this question and am unable to find it. If someone knows of an answer that already exists, I would appreciate being directed to it.
推荐答案
我们可以使用 case_when
在使用 row_number
创建的条件下,即如果行号是4到6,则从该值中减去4,否则返回该值
We can use the case_when
on a condition created with row_number
i.e. if the row number is 4 to 6, subtract 4 from the value or else return the value
df %>%
mutate_at(vars(a:c), funs(case_when(row_number() %in% 4:6 ~ . - 4L,
TRUE ~ .)))
# a b c condition
#1 1 4 2 acap
#2 2 3 1 acap
#3 2 4 3 acap
#4 1 2 4 ncap
#5 1 3 2 ncap
#6 4 3 2 ncap
如果这是基于值而不是行,请在值上创建条件
If this is based on the value instead of the rows, create the condition on the value
df %>%
mutate_at(vars(a:c), funs(case_when(. %in% 5:8 ~ . - 4L,
TRUE ~ .)))
# a b c condition
#1 1 4 2 acap
#2 2 3 1 acap
#3 2 4 3 acap
#4 1 2 4 ncap
#5 1 3 2 ncap
#6 4 3 2 ncap
或者是否基于条件中的值
Or if it is based on the value in the 'condition'
df %>%
mutate_at(vars(a:c), funs(case_when(condition == 'ncap' ~ . - 4L,
TRUE ~ .)))
或者不使用任何 case_when
df %>%
mutate_at(vars(a:c), funs( . - c(0, 4)[(condition == 'ncap')+1]))
# a b c condition
#1 1 4 2 acap
#2 2 3 1 acap
#3 2 4 3 acap
#4 1 2 4 ncap
#5 1 3 2 ncap
#6 4 3 2 ncap
在 base R
,我们可以通过创建索引来实现
In base R
, we can do this by creating the index
i1 <- df$condition =='ncap'
df[i1, 1:3] <- df[i1, 1:3] - 4
数据
data
df <- structure(list(a = c(1L, 2L, 2L, 5L, 5L, 8L), b = c(4L, 3L, 4L,
6L, 7L, 7L), c = c(2L, 1L, 3L, 8L, 6L, 6L), condition = c("acap",
"acap", "acap", "ncap", "ncap", "ncap")), class = "data.frame",
row.names = c(NA, -6L))
这篇关于有条件地将mutate_at应用于R中数据框中的特定行的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!