R if if with for循环 [英] R if else with for loop

问题描述

我想计算比率（A / B = C）。然后我想为比率分配一个标签。如果比率等于0，则标签变为0。如果小于1标签的值为1。最后比率大于1标签得到2。

I would like to calculate a ratio (A / B = C). Then I want to assign a label for ratio. If the ratio equals 0 label gets "0". If value less than 1 label gets "1". Lastly ratio is greater than 1 label gets "2".

以下是示例数据：

                    A            B         C
  1                 0        171.06  0.0000000
  2                 1             2  0.5
  3                 0        120.84  360.00000
  4                 0        308.07  0.0000000
  5                 0        243.06  0.0000000
  6                 0       876.015  0.0000000

以下是循环函数：

targets <- function(data)
{
  label_df <- data[,c("A", "B")]
    label_df[is.na(label_df)] <- 0
    label_df["C"] <- (label_df["A"] / label_df["B"]) 
    for(i in 1:nrow(label_df))
    {
      if(label_df$C == 0){label_df[i,"C"] <- 0}

       else if(label_df$C < 1){label_df[i,"C"] <- 1}
       else {label_df[i,"C"] <- 2}
      }
return(as.data.frame(label_df))
    }

这是结果。它显示所有标签0.

And here is the result. It shows all labels 0.

lab <- target(data)      
head(lab)      

                    A            B         C      label     
  1                 0        171.06  0.0000000    0
  2                 1             2  0.5          0
  3                 0        120.84  360.00000    0
  4                 0        308.07  0.0000000    0
  5                 0        243.06  0.0000000    0
  6                 0       876.015  0.0000000    0

我用table（）函数检查结果吧只显示标签0的所有数据。没有1或2个标签。我无法弄清楚问题出在哪里。有什么想法？

I check the result with table() function and it just shows all data for label 0. There are no 1 or 2 labels. I couldn't figure out where the problem is. Any idea?

推荐答案

我们可以用 cut

We can do this with cut

df1$label <- cut(df1$C, breaks = c(-Inf,0, 1, Inf), labels = c(0, 1, 2))

---

或者 findInterval

findInterval(df1$C, c(0, 1, Inf), left.open = TRUE)

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