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Suppose I have a list:
alist<- list(4,6,8,9)
I want test if each list element is greater than 7 and return a list of 1 if its true and 0 if false.
However I must use lapply.
lapply(alist,if,>7,1) or lapply(alist,if,cond>7,1)
Of course none of these work and I keep getting the following error.
Error: unexpected ',' in "lapply(alist, if,"
744
Format of an lapplylapply returns a list as it's output. In the output list there is one component for each component of the input list and it's value is the result of applying the function to the input component.
lapply() function in R Programming Language is used to apply a function over a list of elements. lapply() function is used with a list and performs the following operations: lapply(List, length): Returns the length of objects present in the list, List.
Difference between lapply() and sapply() functions:lapply() function displays the output as a list whereas sapply() function displays the output as a vector. lapply() and sapply() functions are used to perform some operations in a list of objects.
The lapply() function helps us in applying functions on list objects and returns a list object of the same length. The lapply() function in the R Language takes a list, vector, or data frame as input and gives output in the form of a list object.
It pains me to answer this because it's very un R to do this. You could try being more explicit and use brackets as in:
lapply(alist, function(x) if (x > 7) {1} else {0})
Or the vectorized ifelse
lapply(alist, function(x) ifelse(x > 7, 1, 0))
Or best of all:
as.numeric(alist > 7)
Another two:
lapply(alist > 7, as.integer)
or
lapply(alist > 7, ifelse, 1, 0)
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