CODEWITHSUNDEEP
rsapply
Youssef
Youssef

Reputation: 49

Understanding different sapply output

Why 

kappa <- c(0.0001,0.001,0.01,0.1,0.5,0.9,0.99)

sapply ( kappa, function (t) t)

and 

sapply ( kappa, function (t) print(t))

return different results?

thank you!

Upvotes: 1

Views: 50

Answers (1)

user10624646
user10624646

Reputation:

You missed a comma in your example but you can try this:

kappa <- c(0.0001,0.001,0.01,0.1,0.5,0.9,0.99)

sapply (X=kappa, FUN = function (t)t)

What is happening in sapply is "Simplify apply" which will simplify ON IT'S OWN BY BASE R - it will try and find the best format to simplify the outcome which in this case is the numbers of kappa as a result of the function

as the outcome is based on the function - function(t) t - this just returns the value of t - which is just kappa

however when you are running a print statement so function(t) print(t) - at each "step" of the apply - it is trying to "simplify" the print call - which is why you get this output one after the other :

sapply ( kappa, function (t) t)

also as user above commented:

They are different because in the second case print(t) does two separate things: it prints t on the console and returns t as the result. The first only returns the result, no printing. So the second case is the same, you're just seeing each item printed along the way before sapply finishes

Upvotes: 1

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