问题:

I am unable to figure out how can i write or condition inside which in R. This statemnet does not work.

   which(value>100 | value<=200)

I know it very basic thing but i am unable to find the right solution.

Thanks

回答1:

Every value is either larger than 100 or smaller-or-equal to 200. Maybe you need other numbers or & instead of |? Otherwise, there is no problem with that statement, the syntax is correct:

> value <- c(110, 2, 3, 4, 120)
> which(value>100 | value<=200)
[1] 1 2 3 4 5
> which(value>100 | value<=2)
[1] 1 2 5
> which(value>100 & value<=200)
[1] 1 5

回答2:

> which(iris$Species == "setosa" | iris$Species == "virginica")

 [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
 [19]  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36
 [37]  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54
 [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72
 [73]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90
 [91]  91  92  93  94  95  96  97  98  99 100

does work. Remember to fully qualify the names of the variables you are selecting, as iris$Species in the example at hand (and not only Species).

Have a look at the documentation here.

Also notice that whatever you do with which can be generally done otherwise in a faster and better way.