problem/possible error with mirai_map

[kcmacstat]

In experimenting with mirai_map(), I do not understand why the documented example:
(mat <- matrix(1:4, nrow = 2L))
mirai_map(mat, sum)[.flat]

works fine, but:
(mat <- matrix(1:4, nrow = 2L))
mirai_map(mat, mean)[.flat]

gives the incorrect result of <1 2> instead of the expected <2 3>. What am I doing wrong? In the 2nd case, mirai_map only seems to be considering the first element of each row, rather than the whole row. Thanks in advance for your help...

[shikokuchuo]

sum() takes a ... argument, whereas mean() takes a single x argument and further arguments are passed on to methods (in the case above ignored).

mirai_map() over a matrix or dataframe performs multiple map, so your function .f should take as many arguments as there are elements in a row of your input.

For the example you provide, to give you the result you want:

mirai_map(mat, function(...) mean(c(...)))[.flat]

[shikokuchuo]

The docs and examples have been updated so it hopefully becomes clearer. Thanks for bringing this to light. Please feel free to re-open if you have any further suggestions.