根据相邻列的值替换多列的值 [英] Replace values from multiple columns based on value from adjacent column

问题描述

    # Create a data frame
        > df <- data.frame(a = rnorm(7), b = rnorm(7), c = rnorm(7), threshold = rnorm(7))
        > df <- round(abs(df), 2)
        > 
        > df
             a    b    c threshold
        1 1.17 0.27 1.26      0.19
        2 1.41 1.57 1.23      0.97
        3 0.16 0.11 0.35      1.34
        4 0.03 0.04 0.10      1.50
        5 0.23 1.10 2.68      0.45
        6 0.99 1.36 0.17      0.30
        7 0.28 0.68 1.22      0.56
        > 
        >
    # Replace values in columns a, b, and c with NA if > value in threshold
        > df[1:3][df[1:3] > df[4]] <- "NA"
        Error in Ops.data.frame(df[1:3], df[4]) : 
          ‘>’ only defined for equally-sized data frames

可能有一些我无法生成的明显解决方案.如果值大于阈值"中的值，则目的是将a"、b"和c"列中的值替换为 NA.我需要逐行进行.

There could be some obvious solutions that I am incapable of producing. The intent is to replace values in columns "a", "b", and "c" with NA if the value is larger than that in "threshold". And I need to do that row-by-row.

如果我做对了，df 将如下所示:

If I had done it right, the df would look like this:

         a    b    c threshold
    1   NA   NA   NA      0.19
    2   NA   NA   NA      0.97
    3 0.16 0.11 0.35      1.34
    4 0.03 0.04 0.10      1.50
    5 0.23   NA   NA      0.45
    6   NA   NA 0.17      0.30
    7 0.28   NA   NA      0.56

我也尝试过 apply() 方法，但无济于事.你能帮忙吗??

I had also tried the apply() approach but to no avail. Can you help, please??

推荐答案

你的代码的问题是使用了 df[4] 而不是 df[, 4]>.区别在于 df[4] 返回一个包含一列的 data.frame 而 df[, 4] 返回一个向量.

The problem with your code was the usage of df[4] instead of df[, 4]. The difference is that df[4] returns a data.frame with one column and df[, 4] returns a vector.

这就是为什么

df[1:3] > df[4]

返回

Ops.data.frame(df[1:3], df[4]) 中的错误:'>' 只为同样大小的数据帧定义

error in Ops.data.frame(df[1:3], df[4]) : ‘>’ only defined for equally-sized data frames

虽然这按预期工作

df[1:3][df[1:3] > df[, 4]] <- NA
df
#     a    b    c threshold
#1 0.63 0.74   NA      0.78
#2   NA   NA 0.04      0.07
#3 0.84 0.31 0.02      1.99
#4   NA   NA   NA      0.62
#5   NA   NA   NA      0.06
#6   NA   NA   NA      0.16
#7 0.49   NA 0.92      1.47

数据

set.seed(1)
df <- data.frame(a = rnorm(7), b = rnorm(7), c = rnorm(7), threshold = rnorm(7))
df <- round(abs(df), 2)

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