[英]Mutate a value across several columns using dplyr selectors only
I want to calculate the sd for several columns inside a data frame without leaving my dplyr pipe. 我想在不离开dplyr管道的情况下为数据框内的几列计算sd。 In the past, I have done this by defaulting to base r.
在过去,我默认情况下以r为基数。 I haven't been able to find a solution here that works.
我一直无法在这里找到有效的解决方案。
It may help to provide some context. 这可能有助于提供一些上下文。 This is a process I do to validate survey data.
这是我验证调查数据的过程。 We measure the sd of matrix questions to identify straight-liners.
我们测量矩阵问题的标准差,以识别直线。 An sd of zero across the columns flags a straight line.
跨列的sd为零表示一条直线。 In the past, I calculated this in base R as follows:
过去,我在基数R中对此进行了如下计算:
apply(x, 1, sd)
I know there has to be a way to do this within a dplyr pipe. 我知道必须在dplyr管道中执行此操作。 I've tried several options including pmap and various approaches at mutate_at.
我在mutate_at尝试了多个选项,包括pmap和各种方法。 Here's my latest attempt:
这是我最近的尝试:
library(tidyverse)
set.seed(858465)
scale_points <- c(1:5)
q1 <- sample(scale_points, replace = TRUE, size = 100)
q2 <- sample(scale_points, replace = TRUE, size = 100)
q3 <- sample(scale_points, replace = TRUE, size = 100)
digits = 0:9
createRandString<- function() {
v = c(sample(LETTERS, 5, replace = TRUE),
sample(digits, 4, replace = TRUE),
sample(LETTERS, 1, replace = TRUE))
return(paste0(v,collapse = ""))
}
s_data <- tibble::tibble(resp_id = 100)
for(i in c(1:100)) {
s_data[i,1] <- createRandString()
}
s_data <- bind_cols(s_data, q1 = q1, q2 = q2, q3 = q3)
s_data %>% mutate(vars(starts_with("q"), ~sd(.)))
In a perfect world, I would keep the resp_id variable in the output so that I could generate a report using filter to identify the respondent IDs with sd == 0. 在理想情况下,我会将resp_id变量保留在输出中,以便可以使用过滤器生成报告来标识sd == 0的响应者ID。
Any help is greatly appreciated! 任何帮助是极大的赞赏!
If we need a rowwise sd, 如果我们需要逐行sd,
library(tidyverse)
s_data %>%
mutate(sdQs = select(., starts_with("q")) %>%
pmap_dbl(~ sd(c(...)))) %>%
filter(sdQs == 0)
# A tibble: 9 x 5
# resp_id q1 q2 q3 sdQs
# <chr> <int> <int> <int> <dbl>
#1 JORTY8990R 3 3 3 0
#2 TFYAF4729I 5 5 5 0
#3 VPUYC0789H 4 4 4 0
#4 LHAPM6293X 1 1 1 0
#5 FZQRQ8530P 3 3 3 0
#6 TKTJU3757T 5 5 5 0
#7 AYVHO1309H 4 4 4 0
#8 BBPTZ4822E 5 5 5 0
#9 NGLXT1705B 3 3 3 0
Or another option is rowSds
from matrixStats
或者另一种选择是
rowSds
从matrixStats
library(matrixStats)
s_data %>%
mutate(sdQs = rowSds(as.matrix(.[startsWith(names(.), "q")])))
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