[英]standardize a variable values differently based on another categorical variable in R (Using R Base)
我有一個大型數據集,其中有一個連續變量“膽固醇”,用於每個參與者的兩次訪問(每個參與者有兩行:第一次訪問 = 之前和第二次訪問 = 之后)。 我想對膽固醇進行標准化,但我合並了訪問前和訪問后,這不會使我的標准化准確,因為它是使用平均值和 SD 計算的
使用 R BASE ,我如何在同一數據集中創建一個基於 Visit 標准化的新膽固醇變量(在此過程中標准化應進行兩次;一次用於之前,另一次用於之后,但 output(標准化值)將在再次遵循此 DF 的相同結構的一個變量
DF$Cholesterol<- c( 0.9861551,2.9154158, 3.9302373,2.9453085, 4.2248018,2.4789901, 0.9972635, 0.3879830, 1.1782336, 1.4065341, 1.0495609,1.2750138, 2.8515144, 0.4369885, 2.2410429, 0.7566147, 3.0395565,1.7335131, 1.9242212, 2.4539439, 2.8528908, 0.8432039,1.7002653, 2.3952744,2.6522959, 1.2178764, 2.3426695, 1.9030782,1.1708246,2.7267124)
DF$Visit< -c(Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before,After,Before, After,Before,After,Before,After)
# the standardisation function I want to apply
standardise <- function(x) {return((x-min(x,na.rm = T))/sd(x,na.rm = T))}
先感謝您
讓我們制作您的數據,修復 df$visit 分配,將標准化 function 修復為均值而不是最小值,然后假設之前的每個新場合都是下一個人,pivot 為寬格式,然后改變我們的標准化前后變量:
df <- data.frame(x = rep(1, 30))
df$cholesterol<- c( 0.9861551,2.9154158, 3.9302373,2.9453085, 4.2248018,2.4789901, 0.9972635, 0.3879830, 1.1782336, 1.4065341, 1.0495609,1.2750138, 2.8515144, 0.4369885, 2.2410429, 0.7566147, 3.0395565,1.7335131, 1.9242212, 2.4539439, 2.8528908, 0.8432039,1.7002653, 2.3952744,2.6522959, 1.2178764, 2.3426695, 1.9030782,1.1708246,2.7267124)
df$visit <- rep(c("before", "after"), 15)
standardise <- function(x) {return((x-mean(x,na.rm = T))/sd(x,na.rm = T))}
df <- df %>%
mutate(person = cumsum(visit == "before"))%>%
pivot_wider(names_from = visit, id_cols = person, values_from = cholesterol)%>%
mutate(before_std = standardise(before),
after_std = standardise(after))
給出:
person before after before_std after_std
<int> <dbl> <dbl> <dbl> <dbl>
1 1 0.986 2.92 -1.16 1.33
2 2 3.93 2.95 1.63 1.36
3 3 4.22 2.48 1.91 0.842
4 4 0.997 0.388 -1.15 -1.49
5 5 1.18 1.41 -0.979 -0.356
6 6 1.05 1.28 -1.10 -0.503
7 7 2.85 0.437 0.609 -1.44
8 8 2.24 0.757 0.0300 -1.08
9 9 3.04 1.73 0.788 0.00940
10 10 1.92 2.45 -0.271 0.814
11 11 2.85 0.843 0.611 -0.985
12 12 1.70 2.40 -0.483 0.749
13 13 2.65 1.22 0.420 -0.567
14 14 2.34 1.90 0.126 0.199
15 15 1.17 2.73 -0.986 1.12
如果你真的想要在你的標准化 function 中使用 min 而不是 mean,編輯它應該很簡單。
為 BaseR 解決方案編輯,但有一個警示性的故事,可能有一個更簡潔的解決方案:
df <- data.frame(id = rep(c(seq(1, 15, 1)), each = 2))
df$cholesterol<- c( 0.9861551,2.9154158, 3.9302373,2.9453085, 4.2248018,2.4789901, 0.9972635, 0.3879830, 1.1782336, 1.4065341, 1.0495609,1.2750138, 2.8515144, 0.4369885, 2.2410429, 0.7566147, 3.0395565,1.7335131, 1.9242212, 2.4539439, 2.8528908, 0.8432039,1.7002653, 2.3952744,2.6522959, 1.2178764, 2.3426695, 1.9030782,1.1708246,2.7267124)
df$visit <- rep(c("before", "after"), 15)
df <- reshape(df, direction = "wide", idvar = "id", timevar = "visit")
standardise <- function(x) {return((x-mean(x,na.rm = T))/sd(x,na.rm = T))}
df$before_std <- round(standardise(df$cholesterol.before), 2)
df$aafter_std <- round(standardise(df$cholesterol.after), 2)
給出:
i id cholesterol.before cholesterol.after before_std after_std
1 1 0.9861551 2.9154158 -1.16 1.33
3 2 3.9302373 2.9453085 1.63 1.36
5 3 4.2248018 2.4789901 1.91 0.84
7 4 0.9972635 0.3879830 -1.15 -1.49
9 5 1.1782336 1.4065341 -0.98 -0.36
11 6 1.0495609 1.2750138 -1.10 -0.50
13 7 2.8515144 0.4369885 0.61 -1.44
15 8 2.2410429 0.7566147 0.03 -1.08
17 9 3.0395565 1.7335131 0.79 0.01
19 10 1.9242212 2.4539439 -0.27 0.81
21 11 2.8528908 0.8432039 0.61 -0.99
23 12 1.7002653 2.3952744 -0.48 0.75
25 13 2.6522959 1.2178764 0.42 -0.57
27 14 2.3426695 1.9030782 0.13 0.20
29 15 1.1708246 2.7267124 -0.99 1.12
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