Re: Check whether a range is empty
On Tuesday, 17 July 2018 at 13:59:45 UTC, Gary Willoughby wrote:
I thought every range at the lowest level has an `empty`
property. So, in this case, it would be:
if (PFResutl.toRange.empty)
{
writeln("Empty");
}
Yeah, but it seems, that PFResutl is a range of ranges, and the
OP has the case, where both of the contained ranges are empty.
However, this does not correspond to empty of the governing range.
So
[[], []].empty is false
whereas
[[], []].joiner.empty is true.
Re: Check whether a range is empty
On Friday, 13 July 2018 at 18:37:35 UTC, vino.B wrote:
Hi All,
How do i check whether a range is empty. eg.
(!PFResutl.toRange).empty. I tired the below, but it is no
printing Empty if the range is empty it just prints blank line.
if (!(!PFResutl.toRange).empty) { writeln("Empty"); }
From,
Vino.B
I thought every range at the lowest level has an `empty`
property. So, in this case, it would be:
if (PFResutl.toRange.empty)
{
writeln("Empty");
}
Re: Check whether a range is empty
On 7/15/18 8:56 AM, vino.B wrote: On Sunday, 15 July 2018 at 12:18:27 UTC, Steven Schveighoffer wrote: On 7/15/18 7:45 AM, vino.B wrote: [...] I still don't know why you are using chain here as it equates to the identity function in this instance: https://github.com/dlang/phobos/blob/3d41721141f31059ca6e77dec2da390fad737955/std/range/package.d#L900 Hi Steve, Initially i thought the using "chain" it will merge several ranges for arrays into single range of array, but it doesn't merge into single range of array so i have removed the same from my code. Ahh, I think you want joiner: https://dlang.org/phobos/std_algorithm_iteration.html#joiner -Steve
Re: Check whether a range is empty
On Sunday, 15 July 2018 at 12:18:27 UTC, Steven Schveighoffer wrote: On 7/15/18 7:45 AM, vino.B wrote: [...] I still don't know why you are using chain here as it equates to the identity function in this instance: https://github.com/dlang/phobos/blob/3d41721141f31059ca6e77dec2da390fad737955/std/range/package.d#L900 [...] So I'm assuming from your assertion that this works, that the range is not empty, but yields no elements when it's iterated? Seems like a bug to me. -Steve Hi Steve, Initially i thought the using "chain" it will merge several ranges for arrays into single range of array, but it doesn't merge into single range of array so i have removed the same from my code. From, Vino.B
Re: Check whether a range is empty
On 7/15/18 7:45 AM, vino.B wrote:
On Saturday, 14 July 2018 at 17:20:52 UTC, Ali Çehreli wrote:
First, please show us code that demonstrates the issue.
On 07/14/2018 07:47 AM, vino.B wrote:
> The reason it never prints the text "Empty" is that the
out of the
> "r" is just an empty array.
>
> OUTPUT:
> []
> []
If that's the output of r, then r is not empty but has two elements
and those elements are likely arrays. If they are in fact arrays, them
being empty does not change r: it still has two elements.
If you want to treat the range as empty when all its elements are
empty, then perhaps your problem needs std.algorithm.joiner. The
following program demonstrates your issue with the first assert and
the fix with the second assert:
import std.algorithm;
import std.range;
void main() {
int[][] r = [ [], [] ];
assert(!r.empty);
auto joined_r = r.joiner;
assert(joined_r.empty);
}
joiner joins elements that are ranges themselves. For example,
joiner([ [1], [2] ]) is equal to [ 1, 2 ].
Ali
HI Ali,
Thank you very much, but unfortunately the above solution did not work
as the variable PFResult contains the output from the
workerLocalStorgage which is prited as PFResult.toRange , but was able
to find a solution as below
void ptThreadManager(alias coRoutine, T...)(Array!string Dirlst, T params)
{
alias scRType = typeof(coRoutine(string.init, T.init));
auto PFresult = taskPool.workerLocalStorage!scRType();
PFresult.get ~= coRoutine(FFs, params); }
int a = 0;
if (!(PFresult.toRange).empty) {
foreach(i; chain(PFresult.toRange)) { writeln(i[]); a = a +1;} }
I still don't know why you are using chain here as it equates to the
identity function in this instance:
https://github.com/dlang/phobos/blob/3d41721141f31059ca6e77dec2da390fad737955/std/range/package.d#L900
if(a == 0) { writeln("No files");
So I'm assuming from your assertion that this works, that the range is
not empty, but yields no elements when it's iterated? Seems like a bug
to me.
-Steve
Re: Check whether a range is empty
On Saturday, 14 July 2018 at 17:20:52 UTC, Ali Çehreli wrote:
First, please show us code that demonstrates the issue.
On 07/14/2018 07:47 AM, vino.B wrote:
>The reason it never prints the text "Empty" is that the
out of the
> "r" is just an empty array.
>
> OUTPUT:
> []
> []
If that's the output of r, then r is not empty but has two
elements and those elements are likely arrays. If they are in
fact arrays, them being empty does not change r: it still has
two elements.
If you want to treat the range as empty when all its elements
are empty, then perhaps your problem needs
std.algorithm.joiner. The following program demonstrates your
issue with the first assert and the fix with the second assert:
import std.algorithm;
import std.range;
void main() {
int[][] r = [ [], [] ];
assert(!r.empty);
auto joined_r = r.joiner;
assert(joined_r.empty);
}
joiner joins elements that are ranges themselves. For example,
joiner([ [1], [2] ]) is equal to [ 1, 2 ].
Ali
HI Ali,
Thank you very much, but unfortunately the above solution did
not work as the variable PFResult contains the output from the
workerLocalStorgage which is prited as PFResult.toRange , but was
able to find a solution as below
void ptThreadManager(alias coRoutine, T...)(Array!string Dirlst,
T params)
{
alias scRType = typeof(coRoutine(string.init, T.init));
auto PFresult = taskPool.workerLocalStorage!scRType();
PFresult.get ~= coRoutine(FFs, params); }
int a = 0;
if (!(PFresult.toRange).empty) {
foreach(i; chain(PFresult.toRange)) { writeln(i[]); a = a
+1;} }
if(a == 0) { writeln("No files");
}
From,
Vino.B
Re: Check whether a range is empty
First, please show us code that demonstrates the issue.
On 07/14/2018 07:47 AM, vino.B wrote:
>The reason it never prints the text "Empty" is that the out of the
> "r" is just an empty array.
>
> OUTPUT:
> []
> []
If that's the output of r, then r is not empty but has two elements and
those elements are likely arrays. If they are in fact arrays, them being
empty does not change r: it still has two elements.
If you want to treat the range as empty when all its elements are empty,
then perhaps your problem needs std.algorithm.joiner. The following
program demonstrates your issue with the first assert and the fix with
the second assert:
import std.algorithm;
import std.range;
void main() {
int[][] r = [ [], [] ];
assert(!r.empty);
auto joined_r = r.joiner;
assert(joined_r.empty);
}
joiner joins elements that are ranges themselves. For example, joiner([
[1], [2] ]) is equal to [ 1, 2 ].
Ali
Re: Check whether a range is empty
On Saturday, 14 July 2018 at 14:28:52 UTC, vino.B wrote:
On Friday, 13 July 2018 at 19:45:03 UTC, Steven Schveighoffer
wrote:
On 7/13/18 3:29 PM, vino.B wrote:
[...]
Well, empty is how you detect whether any range is empty, and
as far as ranges are concerned, your code is correctly
checking for empty.
A couple comments:
1. Why are you using chain with a single parameter? That just
returns its parameter.
2. You may want to try grabbing the range ONCE. i.e.:
auto r = PFresult.toRange;
if(!r.empty)
{
foreach(i; r) ...
}
I'm not familiar with how taskPool works, so I don't know the
real answer.
-Steve
Hi Steve,
i Tried your method no luck, it just prints blank lines.
From,
Vino.B
Hi Steve,
The reason it never prints the text "Empty" is that the out of
the "r" is just an empty array.
OUTPUT:
[]
[]
From,
Vino.B
Re: Check whether a range is empty
On Friday, 13 July 2018 at 19:45:03 UTC, Steven Schveighoffer
wrote:
On 7/13/18 3:29 PM, vino.B wrote:
[...]
Well, empty is how you detect whether any range is empty, and
as far as ranges are concerned, your code is correctly checking
for empty.
A couple comments:
1. Why are you using chain with a single parameter? That just
returns its parameter.
2. You may want to try grabbing the range ONCE. i.e.:
auto r = PFresult.toRange;
if(!r.empty)
{
foreach(i; r) ...
}
I'm not familiar with how taskPool works, so I don't know the
real answer.
-Steve
Hi Steve,
i Tried your method no luck, it just prints blank lines.
From,
Vino.B
Re: Check whether a range is empty
On 7/13/18 3:29 PM, vino.B wrote:
On Friday, 13 July 2018 at 19:05:20 UTC, Steven Schveighoffer wrote:
On 7/13/18 2:37 PM, vino.B wrote:
Hi All,
How do i check whether a range is empty. eg.
(!PFResutl.toRange).empty. I tired the below, but it is no printing
Empty if the range is empty it just prints blank line.
if (!(!PFResutl.toRange).empty) { writeln("Empty"); }
Without knowing what PFResutl is, let me simplify a bit:
if( ! (expr).empty) { writeln("Empty"); }
That exclamation point means "not". So you are first checking if the
range is NOT empty, and if so, printing "Empty". Is that what you meant?
Sorry there was a typo mistake, so the PFResult contain the results of
"taskPool.workerLocalStorage" which i print using
writeln(PFResult.toRange) so the requirement is that if the rage is
empty it has to print "Empty" else it should print the result.
Eg:
if (!(PFresult.toRange).empty) {
foreach(i; chain(PFresult.toRange)) { writeln(i[]); }
} else { writeln("Empty"); }
Well, empty is how you detect whether any range is empty, and as far as
ranges are concerned, your code is correctly checking for empty.
A couple comments:
1. Why are you using chain with a single parameter? That just returns
its parameter.
2. You may want to try grabbing the range ONCE. i.e.:
auto r = PFresult.toRange;
if(!r.empty)
{
foreach(i; r) ...
}
I'm not familiar with how taskPool works, so I don't know the real answer.
-Steve
Re: Check whether a range is empty
On Friday, 13 July 2018 at 19:05:20 UTC, Steven Schveighoffer
wrote:
On 7/13/18 2:37 PM, vino.B wrote:
Hi All,
How do i check whether a range is empty. eg.
(!PFResutl.toRange).empty. I tired the below, but it is no
printing Empty if the range is empty it just prints blank line.
if (!(!PFResutl.toRange).empty) { writeln("Empty"); }
Without knowing what PFResutl is, let me simplify a bit:
if( ! (expr).empty) { writeln("Empty"); }
That exclamation point means "not". So you are first checking
if the range is NOT empty, and if so, printing "Empty". Is that
what you meant?
-Steve
Hi Steve,
Sorry there was a typo mistake, so the PFResult contain the
results of "taskPool.workerLocalStorage" which i print using
writeln(PFResult.toRange) so the requirement is that if the rage
is empty it has to print "Empty" else it should print the result.
Eg:
if (!(PFresult.toRange).empty) {
foreach(i; chain(PFresult.toRange)) { writeln(i[]); }
} else { writeln("Empty"); }
From,
Vino.B
Re: Check whether a range is empty
On 7/13/18 2:37 PM, vino.B wrote:
Hi All,
How do i check whether a range is empty. eg.
(!PFResutl.toRange).empty. I tired the below, but it is no printing
Empty if the range is empty it just prints blank line.
if (!(!PFResutl.toRange).empty) { writeln("Empty"); }
Without knowing what PFResutl is, let me simplify a bit:
if( ! (expr).empty) { writeln("Empty"); }
That exclamation point means "not". So you are first checking if the
range is NOT empty, and if so, printing "Empty". Is that what you meant?
-Steve
