Dear R Team

The following line returns 0 (zero) as answer:

sum(c(NA_real_, NA_real_, NA_real_, NA_real_), na.rm = TRUE)

One would, however, have expected it to return 'NaN', as is the case with

function 'mean':

> mean(c(NA_real_, NA_real_, NA_real_, NA_real_), na.rm = TRUE)

[1] NaN

The problem in other words:

I have a vector filled with missing numbers. I run the 'sum' function on

it, but instruct it to remove all missing values first. Consequently, the

sum function is left with an empty numeric vector. There is nothing to sum

over, so it shouldn't actually be able to return a concrete numeric value?

Shouldn't it thus rather return either NA ('unknown'/'missing') or - in the

fashion of the mean function - NaN ('not a number')?

With the current state of affairs, the sum function poses the grave danger

of introducing zeros to one's data (and subsequently other values as well,

as soon as the zeros get taken up in further calculations).

I hope my e-mail finds you well and I wish the R team all of the best for

2017 :)

Kind regards

Alex I. Howard

Web: www.nova.org.za

Phone: +27 (0) 44 695 0749

VoiP: +27 (0) 87 751 3490

Fax: +27 (0) 86 538 7958

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