[英]R: for loop output save only last results in output dataframe
我有以下 for 循環腳本:
# Create example data
dataKM <- data.frame(x1 = 1:5,
x2 = 6:10,
x3 = 11:15)
# Duplicate dataframe
datatest <- dataKM[c(1:3)]
# for loop
for(i in colnames(dataKM[,2:ncol(dataKM)])) {
# median of each single column of dataframe
median <- median(dataKM[,i])
# add column in duplicated dataframe with 'High' or 'low' based on median for each column
datatest$median[dataKM[,i] <= median ] <- "Low"
datatest$median[dataKM[,i] > median ] <- "High"
}
我正在嘗試對dataKM dataframe的每一列重復for循環,並將結果保存為數據集dataframe中的列。 我的腳本只保存最后一次迭代。 可能我得到一個 output 因為我在循環中的每次傳遞時覆蓋了以前的值。 我想知道如何將所有 for loop output 保存在各自的列中。 誰能幫我? 非常感謝,我希望這對嘗試做類似事情的其他人也有用。
我們可以使用lapply
function
datatest <- dataKM[c(2:3)]
datatest[] <- lapply(dataKM[-1] , function(x) ifelse(x <= median(x) , "Low" , "High"))
colnames(datatest) <- c("x2Median" , "x3Median")
cbind(dataKM , datatest)
x1 x2 x3 x2Median x3Median
1 1 6 11 Low Low
2 2 7 12 Low Low
3 3 8 13 Low Low
4 4 9 14 High High
5 5 10 15 High High
如果你堅持使用for loop
試試這個
datatest <- dataKM[c(1:3)]
for(i in colnames(dataKM[-1])) {
median <- median(dataKM[,i])
datatest[[paste0(i,"median")]][dataKM[,i] <= median ] <- "Low"
datatest[[paste0(i,"median")]][dataKM[,i] > median ] <- "High"
}
我不確定什么與什么比較。 但這里有一個示例,將 x2 值或 x3 值與其列中位數進行比較:
這是 dplyr 方法:
library(dplyr)
dataKM %>%
mutate(across(-1, ~case_when(. <= median(., na.rm=TRUE) ~ "Low",
. > median(., nar.rm=TRUE) ~ "High"), .names = "Median_{.col}"))
x1 x2 x3 Median_x2 Median_x3
1 1 6 11 Low Low
2 2 7 12 Low Low
3 3 8 13 Low Low
4 4 9 14 High High
5 5 10 15 High High
目前,您正在更新一個新列median 。 只需調整以在for
循環的每次迭代中創建新的中值列,將列當前列名稱和中值連接起來。
# for loop
for(col in colnames(dataKM[,2:ncol(dataKM)])) {
curr_col <- dataKM[[col]]
# median of each single column of dataframe
col_median <- median(curr_col)
# add column in duplicated dataframe with 'High' or 'low' based on median for each column
datatest[[paste0(col, "_median")]][curr_col <= col_median] <- "Low"
datatest[[paste0(col, "_median")]][curr_col > col_median] <- "High"
}
或者,使用ifelse
:
for(col in colnames(dataKM[,2:ncol(dataKM)])) {
curr_col <- dataKM[[col]]
col_median <- median(curr_col)
datatest[[paste0(col, "_median")]] <- ifelse(
curr_col <= col_median, "Low", " High"
)
}
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