来自多个if/else if语句的多个动作-R [英] Multiple actions from multiple if / else if statements - R

问题描述

我是R的新手，并且遇到了在数据帧内正确填充一列数据的问题.我正在使用一系列if/else if语句基于另一列(P_Value)填充两列(P_Score和P_Class).

I'm new to R and am experiencing a problem properly populating a column of data within a data frame. I'm populating two columns (P_Score and P_Class) based on another column (P_Value) using a series of if / else if statements.

i<- 0
nr<- nrow(myData)
while(i<nr){
  i<-1+i
  if(toString(myData$P_Value[i])=="NA"){ myData$P_Score[i] <- myData$P_Value[i]
  } else if (as.numeric(toString(myData$P_Value[i]))<5){
      myData$P_Score[i] <- 1; myData$P_Class[i] <- "Minimal Depression";
  } else if (as.numeric(toString(myData$P_Value[i]))<10){
      myData$P_Score[i] <- 2; myData$P_Class[i] <- "Mild Depression";
  } else if (as.numeric(toString(myData$P_Value[i]))<15){
      myData$P_Score[i] <- 3; myData$P_Class[i] <- "Moderate Depression";
  } else if (as.numeric(toString(myData$P_Value[i]))<20){
      myData$P_Score[i] <- 4; myData$P_Class[i] <- "Moderate-Severe Depression";
  } else 
      myData$P_Score[i] <- 5; myData$P_Class[i] <- "Severe Depression";
}

但是，这并没有给我我想要的结果，相反，我想到了:

However, this is not giving me my desired result, and instead I wind up with this:

P_Value  P_Score    P_Class
4        1          Severe Depression
25       5          Severe Depression
8        2          Severe Depression
13       3          Severe Depression
17       4          Severe Depression
1        1          Severe Depression
12       3          Severe Depression

因此P_Score可以很好地填充，但是P_Class始终默认为严重抑郁".我必须在执行基于if条件的多个语句时遇到一些问题，但是我无法弄清楚我在做什么错.我在其他地方读过，只要您在分号后都加分号即可，但这显然行不通.

So the P_Score is populating just fine, but the P_Class is always defaulting to "Severe Depression". I must be having some issue executing multiple statements based off of 1 if condition, but I can't figure out what I'm doing wrong. I have read elsewhere as long as you put semicolons after the statements both should work, but that's clearly not working.

我还尝试过将命令间隔开:

I have also tried spacing out the commands like this:

} else if (as.numeric(toString(myData$P_Value[i]))<5){
  myData$P_Score[i] <- 1
  myData$P_Class[i] <- "Minimal Depression"

但这似乎也不起作用.请帮忙！

But that does not seem to work either. Please help!

推荐答案

R为此提供了一个功能，不需要任何循环.请阅读?cut :

R has a function for this, there is no need for any loops. Please read ?cut:

设置示例

myData
#   P_Value
# 1       4
# 2      25
# 3       8
# 4      13
# 5      17
# 6       1
# 7      12
# 8      NA

grps <- cut(myData$P_Value, 
          breaks=c(-Inf, 5, 10, 15, 20, Inf), 
          labels=c("Min Dep", "Mild Dep", "Mod Dep", "Mod-Sev Dep", "Sev Dep"))

创建了分组后，我们可以从中创建一个得分和类别"列

With the groups created, we can make a Score and Class column from it

myData$P_Score <- as.numeric(grps)
myData$P_Class <- grps
myData
#   P_Value P_Score     P_Class
# 1       4       1     Min Dep
# 2      25       5     Sev Dep
# 3       8       2    Mild Dep
# 4      13       3     Mod Dep
# 5      17       4 Mod-Sev Dep
# 6       1       1     Min Dep
# 7      12       3     Mod Dep
# 8      NA      NA        <NA>

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