Interpreting condition has length 1 warning from if function

Question

I have an array   a  lt - c 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  1  0  0  0  0  0  0  0  0  0  1  0  0  0  0  0  0  0  0  1  1  0  0  1  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  1  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0    and would like to implement the following function   w lt -function a     if  a gt 0       a sum a        else 1     This function would like to check whether there is any value in a larger than 0 and if yes then divide each element by the sum of the total   Otherwise it should just record 1   I get the following warning message     Warning message   In if  a  gt  0       the condition has length  gt  1 and only the first element will be used   How can I correct the function

User · Answer

Just adding a point to the whole discussion as to why this warning comes up (It wasn't clear to me before). The reason one gets this is as mentioned before is because 'a' in this case is a vector and the inequality 'a>0' produces another vector of TRUE and FALSE (where 'a' is >0 or not).

If you would like to instead test if any value of 'a>0', you can use functions - 'any' or 'all'

Best

User · Answer

maybe you want ifelse   a  lt - c 1 1 1 1 0 0 0 0 2 2  ifelse a gt 0 a sum a  1     1  0 125 0 125 0 125 0 125 1 000 1 000 1 000 1 000   9  0 250 0 250

User · Answer

if statement is not vectorized  For vectorized if statements you should use ifelse  In your case it is sufficient to write  w  lt - function a   if  any a gt 0      a sum a      else 1     or a short vectorised version  ifelse a  gt  0  a sum a   1    It depends on which do you want to use  because first function gives output vector of length 1  in else part  and ifelse gives output vector of length equal to length of a

User · Answer

Here s an easy way without ifelse    a sum a    a gt 0    An example   a  lt - c 0  1  0  0  1  1  0  1    a sum a    a gt 0    1  1 00 0 25 1 00 1 00 0 25 0 25 1 00 0 25

User · Answer

The way I cam across this question was when I tried doing something similar where I was defining a function and it was being called with the array like others pointed out  You could do something like this however for this scenarios its less elegant compared to Sven s method   sapply a  function x  afunc x    afunc lt -function a     if  a gt 0       a sum a        else 1

User · Answer

Use lapply function after creating your function normally   lapply x  your input   fun  insert your function name     lapply gives a list so use unlist function to take them out of the function  unlist lapply a w

[r] Interpreting "condition has length > 1" warning from `if` function

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