if循环中的ifelse不会产生所需的输出 [英] Ifelse in a for loop not yielding desired output

问题描述

我有一个包含2列的数据集，即time（Ti）和counter（Co）。每当计数器为1时，我应该计算行时间和之前行时间之间的时间差。

I have a dataset with 2 columns namely, "time(Ti)" and "counter(Co)". Whenever the counter is 1 , I am supposed to calculate time difference between that "row time" and previous "row time" .

为了达到上述要求，我正在使用以下逻辑

To achieve the above requirement, I am using the below logic

for (i in 1:length(file1$counter))
{  
  n1 <-  ifelse(file1$counter==1,(file1$TIME[(i)] - file1$TIME[(i-1)]),0)
}

但我得到的标准输出为 0 0 2 2 2 2 2 0 0 0 0 0 0 2 2 2 2 2 0 0 而不是 0 0 2 1 4 1 4 0 0 0 0 0 0 2 2 2 2 2 0 0
此外，n1默认显示为时间序列，Start = 1，End = 20，
Frequency = 1.

But I am getting a standard output as 0 0 2 2 2 2 2 0 0 0 0 0 0 2 2 2 2 2 0 0 instead of 0 0 2 1 4 1 4 0 0 0 0 0 0 2 2 2 2 2 0 0 Also the n1 is by default shown as Time Series with Start = 1, End = 20 and Frequency = 1.

推荐答案

如docendo discimus所述， ifelse 是R中的向量化操作。您可以省略 for 循环以便得到想要的结果。这是一个例子：

As docendo discimus noted, ifelse is a vectorized operation in R. You can omit the for loop in order to get the desired result. Here's an example:

filename   = c("aa", "bb", "cc") 
counter    = c(1, 2, 3) 
df = data.frame(filename, counter) 
df$n1 <- ifelse(df$counter == 1, "one", "other")

这给了我们一个更新的 df ： / p>

Which gives us an updated df of:

  filename counter    n1
1       aa       1   one
2       bb       2 other
3       cc       3 other

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