Re: [Qgis-user] QGIS2.8 How are the features ordered when using layer.selectedFeatures()

[Raymond Nijssen]

Hi,

I found two ways of doing that, I think the second is faster but not 
sure. (And I think they will both be slower than the random order code 
you were using before, but the order will remain.)


Good luck,
Raymond


---

layer = iface.activeLayer()

ids = layer.selectedFeatureIds()
print(ids)

# first option, loop all features and test if the id is in
# the selected ids:

for feat in layer.getFeatures():
if feat.id() in ids:
print(feat)


# second option, loop selected ids and get their feature:

ids.sort()
print(ids)

for id in ids:
feat = layer.getFeature(id)
print(feat)





On 04-06-19 06:01, Zhang Qun wrote:
Thanks Nyall. Then is there anyway i can get the original order? My data 
is road lane points and the sequence order represent the driving direction.


On Tue, Jun 4, 2019, 11:58 AM Nyall Dawson > wrote:


On Tue, 4 Jun 2019 at 13:38, Zhang Qun mailto:zhangq@gmail.com>> wrote:
 >
 > Hi,
 > Does anyone know how the features are ordered when you extract by
selectedFeatures()? Is it in the same order as the input delimited
text file? I'm asking because sometimes I found the looping does not
give me the same order as in my data source.

It's an unordered set - i.e. effectively random.

Nyall


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Re: [Qgis-user] QGIS2.8 How are the features ordered when using layer.selectedFeatures()

[Zhang Qun]

Thanks Nyall. Then is there anyway i can get the original order? My data is
road lane points and the sequence order represent the driving direction.

On Tue, Jun 4, 2019, 11:58 AM Nyall Dawson  wrote:

> On Tue, 4 Jun 2019 at 13:38, Zhang Qun  wrote:
> >
> > Hi,
> > Does anyone know how the features are ordered when you extract by
> selectedFeatures()? Is it in the same order as the input delimited text
> file? I'm asking because sometimes I found the looping does not give me the
> same order as in my data source.
>
> It's an unordered set - i.e. effectively random.
>
> Nyall
>
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Re: [Qgis-user] QGIS2.8 How are the features ordered when using layer.selectedFeatures()

[Nyall Dawson]

On Tue, 4 Jun 2019 at 13:38, Zhang Qun  wrote:
>
> Hi,
> Does anyone know how the features are ordered when you extract by 
> selectedFeatures()? Is it in the same order as the input delimited text file? 
> I'm asking because sometimes I found the looping does not give me the same 
> order as in my data source.

It's an unordered set - i.e. effectively random.

Nyall
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[Qgis-user] QGIS2.8 How are the features ordered when using layer.selectedFeatures()

[Zhang Qun]

Hi,
Does anyone know how the features are ordered when you extract by
selectedFeatures()? Is it in the same order as the input delimited text
file? I'm asking because sometimes I found the looping does not give me the
same order as in my data source.

selected_features = layer.selectedFeatures()
for f in selected_features:

Thanks.
Ethan
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