On Thursday, 9 November 2017 at 12:40:49 UTC, Vino wrote:
Hi All,
Request your help, when i execute the below line of code i am
getting an error message as "Cannot reduce an empty iterable
w/o an explicit seed value" , The below lie of code will
iterate several file system and will report the size of the
folder (level 1) which is greater than 10GB.
Program:
auto coSizeDirList (string FFs, int SizeDir) {
float subdirTotal;
float subdirTotalGB;
Array!string Result;
auto dFiles = Array!string ((dirEntries(FFs,
SpanMode.shallow).filter!(a => a.isDir))[].map!(a => a.name));
foreach (d; parallel(dFiles[], 1)) {
auto SdFiles = Array!float ((dirEntries(join(["\\\\?\\", d]),
SpanMode.depth).filter!(a => a.isFile))[].map!(a =>
to!float(a.size)));
{
subdirTotalGB = ((reduce!((a,b) => a + b)(SdFiles)) / 1024 /
1024 / 1024);
}
if (subdirTotalGB > SizeDir) {
Result.insertBack(d);
Result.insertBack(to!string(subdirTotalGB));
}
}
return Result;
}
From,
Vino.B
The problem is
subdirTotalGB = ((reduce!((a,b) => a + b)(SdFiles)) / 1024 / 1024
/ 1024);
with reduce you need to give it a seed (an initial value to start
with).
See
https://dlang.org/phobos/std_algorithm_iteration.html#.reduce
int[] arr = [ 1, 2, 3, 4, 5 ];
// Sum all elements
auto sum = reduce!((a,b) => a + b)(0, arr);
writeln(sum); // 15
// Sum again, using a string predicate with "a" and "b"
sum = reduce!"a + b"(0, arr);
writeln(sum); // 15
To your actual use case, you can do:
foreach (d; parallel(dFiles[], 1)) {
float subdirTotalGB = dirEntries(join(["\\\\?\\", d]),
SpanMode.depth)
.filter!(a => a.isFile))
.map!(a => to!float(a.size)))
.fold!((a, b) => a + b)(0) // Provide an explicit seed.
if (subdirTotalGB > SizeDir) {
Result.insertBack(d);
Result.insertBack(to!string(subdirTotalGB));
}
}
