Re: [Qgis-user] different buffer for the same field

[Marco Grisolia]

I solved both cases of the previous email.
If you want to buffer starting from a specified distance stored in a field,
please have a look on this post [0] (written by me):

[0] https://howtoinqgis.wordpress.com/2016/11/28/how-to-buffer-v
ectors-from-fields-in-qgis-using-python/

If you want to directly buffer (for your specific case) without any
preliminary edit on the layer, copy the code at the end of this
email: it was adapted from the link above (please refer to it for a clear
comprehension)

For both cases, you may decide to buffer all the features or only the
selected ones.
I hope it would be useful.
Best regards,
Marco

 code below 

##Input_Layer=vector
##Segments=number 30
##Buffer_only_selected_features=Boolean False

from qgis.core import *
from qgis.PyQt.QtCore import QVariant
import math

layer = processing.getObject(Input_Layer)
crs = layer.crs().toWkt()

# Create a dictionary with the preferred distances
distances = {'normal fault': 30, 'inverse fault': 20, 'Overthrust': 50,
'Syncline': 20}

# Create the output layer
outLayer = QgsVectorLayer('Polygon?crs='+ crs, 'outLayer' , 'memory')
prov = outLayer.dataProvider()
fields = layer.pendingFields() # Fields from the input layer
#fields.append(QgsField('drawn_area', QVariant.Double, '', 10, 3))
prov.addAttributes(fields) # Add input layer fields to the outLayer
outLayer.updateFields()

# Check for selected features
if layer.selectedFeatures() and Buffer_only_selected_features is True:
features = layer.selectedFeatures()
else:
features = layer.getFeatures()

# Generate buffers
for feat in features:
inAttr = feat.attributes() # Input attributes
inGeom = feat.geometry() # Input geometry
bf_inGeom = inGeom.buffer(distances[feat['type']], Segments)
poly=bf_inGeom.asPolygon()
drawn_area = bf_inGeom.area()
inAttr.append(drawn_area)
outGeom = QgsFeature()
outGeom.setGeometry(QgsGeometry.fromPolygon(poly))
outGeom.setAttributes(inAttr) # Output attributes
prov.addFeatures([outGeom]) # Output geometry

# Add the layer to the Layers panel
QgsMapLayerRegistry.instance().addMapLayer(outLayer)

 end of the code 


2016-11-27 20:11 GMT+01:00 Marco Grisolia :

> Don't worry for the delay...
> Your goal is to generate the buffer a priori (i.e. by assigning a
> specific value of radius for each feature, without any preliminary
> edit on the layer) or by searching for it in a field of the layer
> (i.e. as Randal Hale suggested)?
> Marco
>
> 2016-11-27 18:54 GMT+01:00 Azzurra Lentini :
> > Dear Marco, apologies to write you only now.
> > Yes with variable distance buffer is fine. Thanks a lot.
> >
> > If you can, could you please write me the PyQgis script for the other
> > option?
> >
> > all regards, Azzurra
> >
> > 2016-11-16 9:22 GMT+01:00 Marco Grisolia :
> >>
> >> If you want to assign a specified buffer for each kind of feature, you
> >> may use a simple PyQGIS script using a call of buffer() from
> >> QgsGeometry(). Are you able to do it? Otherwise I may try to write it
> >> for you if my understanding of the problem was right.
> >> Therefore, if your buffer distances are inside a field, you may use
> >> the "Variable Distance Buffer" algorithm from Processing.
> >> Best regards,
> >> Marco
> >>
> >> 2016-11-16 1:26 GMT+01:00 Azzurra Lentini :
> >> > Dear all,
> >> >
> >> > I have a shape file with a field called “type”.  In the “type”  field
> I
> >> > have
> >> > 4 kinds of samples ( 19 records).
> >> >
> >> > See in the attachment.
> >> >
> >> > The 4 samples are: normal fault, inverse fault, overthrust, syncline.
> >> >
> >> > I would like to create a buffer with different distance for each
> sample
> >> > (the
> >> > best it would be to obtain a shape with 5 different buffer distances).
> >> >
> >> > For example  the buffer distance for the sample “ normal fault” is 30
> m,
> >> > for
> >> > the “inverse fault “ is 20 m, for the “overthrust” is 50 m and for the
> >> > “syncline” is 20 m.
> >> >
> >> >
> >> >
> >> > How I can do this kind of buffer??
> >> >
> >> >
> >> >
> >> > Thanks A.L.
> >> >
> >> >
> >> >
> >> >
> >> > --
> >> > Dr. Hydrogeologist
> >> > AZZURRA LENTINI
> >> > Expert of evaluation environmental hazards
> >> > GIS application
> >> > Haity Mobile Tel: 0050946057393
> >> > ++
> >> > Italy Mobile Tel.: **(39) 338 24 40 676
> >> > ++
> >> > SKYPE azzurrahydro
> >> > ++
> >> > azzurralent...@gmail.com
> >> > ++
> >> > *Par respect pour l'environnement,*
> >> >
> >> > *n'imprimez ce mail qu'en cas d'absolue nécessité*
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > ___
> >> > Qgis-user mailing list
> >> > Qgis-user@lists.osgeo.org
> >> > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> >> > 

Re: [Qgis-user] different buffer for the same field

[Marco Grisolia]

Don't worry for the delay...
Your goal is to generate the buffer a priori (i.e. by assigning a
specific value of radius for each feature, without any preliminary
edit on the layer) or by searching for it in a field of the layer
(i.e. as Randal Hale suggested)?
Marco

2016-11-27 18:54 GMT+01:00 Azzurra Lentini :
> Dear Marco, apologies to write you only now.
> Yes with variable distance buffer is fine. Thanks a lot.
>
> If you can, could you please write me the PyQgis script for the other
> option?
>
> all regards, Azzurra
>
> 2016-11-16 9:22 GMT+01:00 Marco Grisolia :
>>
>> If you want to assign a specified buffer for each kind of feature, you
>> may use a simple PyQGIS script using a call of buffer() from
>> QgsGeometry(). Are you able to do it? Otherwise I may try to write it
>> for you if my understanding of the problem was right.
>> Therefore, if your buffer distances are inside a field, you may use
>> the "Variable Distance Buffer" algorithm from Processing.
>> Best regards,
>> Marco
>>
>> 2016-11-16 1:26 GMT+01:00 Azzurra Lentini :
>> > Dear all,
>> >
>> > I have a shape file with a field called “type”.  In the “type”  field I
>> > have
>> > 4 kinds of samples ( 19 records).
>> >
>> > See in the attachment.
>> >
>> > The 4 samples are: normal fault, inverse fault, overthrust, syncline.
>> >
>> > I would like to create a buffer with different distance for each sample
>> > (the
>> > best it would be to obtain a shape with 5 different buffer distances).
>> >
>> > For example  the buffer distance for the sample “ normal fault” is 30 m,
>> > for
>> > the “inverse fault “ is 20 m, for the “overthrust” is 50 m and for the
>> > “syncline” is 20 m.
>> >
>> >
>> >
>> > How I can do this kind of buffer??
>> >
>> >
>> >
>> > Thanks A.L.
>> >
>> >
>> >
>> >
>> > --
>> > Dr. Hydrogeologist
>> > AZZURRA LENTINI
>> > Expert of evaluation environmental hazards
>> > GIS application
>> > Haity Mobile Tel: 0050946057393
>> > ++
>> > Italy Mobile Tel.: **(39) 338 24 40 676
>> > ++
>> > SKYPE azzurrahydro
>> > ++
>> > azzurralent...@gmail.com
>> > ++
>> > *Par respect pour l'environnement,*
>> >
>> > *n'imprimez ce mail qu'en cas d'absolue nécessité*
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > ___
>> > Qgis-user mailing list
>> > Qgis-user@lists.osgeo.org
>> > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
>> > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
>
>
>
>
> --
> Dr. Hydrogeologist
> AZZURRA LENTINI
> Expert of evaluation environmental hazards
> GIS application
> Haity Mobile Tel: 0050946057393
> ++
> Italy Mobile Tel.: **(39) 338 24 40 676
> ++
> SKYPE azzurrahydro
> ++
> azzurralent...@gmail.com
> ++
> *Par respect pour l'environnement,*
>
> *n'imprimez ce mail qu'en cas d'absolue nécessité*
>
>
>
>
>
>
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Re: [Qgis-user] different buffer for the same field

[Azzurra Lentini]

Dear Marco, apologies to write you only now.
Yes with variable distance buffer is fine. Thanks a lot.

If you can, could you please write me the PyQgis script for the other
option?

all regards, Azzurra

2016-11-16 9:22 GMT+01:00 Marco Grisolia :

> If you want to assign a specified buffer for each kind of feature, you
> may use a simple PyQGIS script using a call of buffer() from
> QgsGeometry(). Are you able to do it? Otherwise I may try to write it
> for you if my understanding of the problem was right.
> Therefore, if your buffer distances are inside a field, you may use
> the "Variable Distance Buffer" algorithm from Processing.
> Best regards,
> Marco
>
> 2016-11-16 1:26 GMT+01:00 Azzurra Lentini :
> > Dear all,
> >
> > I have a shape file with a field called “type”.  In the “type”  field I
> have
> > 4 kinds of samples ( 19 records).
> >
> > See in the attachment.
> >
> > The 4 samples are: normal fault, inverse fault, overthrust, syncline.
> >
> > I would like to create a buffer with different distance for each sample
> (the
> > best it would be to obtain a shape with 5 different buffer distances).
> >
> > For example  the buffer distance for the sample “ normal fault” is 30 m,
> for
> > the “inverse fault “ is 20 m, for the “overthrust” is 50 m and for the
> > “syncline” is 20 m.
> >
> >
> >
> > How I can do this kind of buffer??
> >
> >
> >
> > Thanks A.L.
> >
> >
> >
> >
> > --
> > Dr. Hydrogeologist
> > AZZURRA LENTINI
> > Expert of evaluation environmental hazards
> > GIS application
> > Haity Mobile Tel: 0050946057393
> > ++
> > Italy Mobile Tel.: **(39) 338 24 40 676
> > ++
> > SKYPE azzurrahydro
> > ++
> > azzurralent...@gmail.com
> > ++
> > *Par respect pour l'environnement,*
> >
> > *n'imprimez ce mail qu'en cas d'absolue nécessité*
> >
> >
> >
> >
> >
> >
> >
> > ___
> > Qgis-user mailing list
> > Qgis-user@lists.osgeo.org
> > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
>



-- 
Dr. Hydrogeologist
AZZURRA LENTINI
Expert of evaluation environmental hazards
GIS application
Haity Mobile Tel: 0050946057393
++
Italy Mobile Tel.: **(39) 338 24 40 676
++
SKYPE azzurrahydro
++
azzurralent...@gmail.com
++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*
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Re: [Qgis-user] different buffer for the same field

[Randal Hale]

In the processing Toolbox there is a tool called Variable Distance Buffer.

If you add a field to your data giving each type a width (field called 
bufferwidth and it is 10, 20, 30 , 40 meters for each type) - you can 
use that tool to automatically buffer each fault accordingly.


Good Luck!

Randy


On 11/15/2016 07:26 PM, Azzurra Lentini wrote:


Dear all,

I have a shape file with a field called “type”.  In the “type”  field 
I have 4 kinds of samples ( 19 records).


See in the attachment.

The 4 samples are: normal fault, inverse fault, overthrust, syncline.

I would like to create a buffer with different distance for each 
sample (the best it would be to obtain a shape with 5 different buffer 
distances).


For example  the buffer distance for the sample “ normal fault” is 30 
m, for the “inverse fault “ is 20 m, for the “overthrust” is 50 m and 
for the “syncline” is 20 m.


How I can do this kind of buffer??

Thanks A.L.


--
Dr. Hydrogeologist
AZZURRA LENTINI
Expert of evaluation environmental hazards
GIS application
Haity Mobile Tel: 0050946057393
++
Italy Mobile Tel.: **(39) 338 24 40 676
++
SKYPE azzurrahydro
++
azzurralent...@gmail.com 
++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*








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--
-
Randal Hale
North River Geographic Systems, Inc
http://www.northrivergeographic.com
423.653.3611 rjh...@northrivergeographic.com
twitter:rjhale

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Re: [Qgis-user] different buffer for the same field

[Marco Grisolia]

If you want to assign a specified buffer for each kind of feature, you
may use a simple PyQGIS script using a call of buffer() from
QgsGeometry(). Are you able to do it? Otherwise I may try to write it
for you if my understanding of the problem was right.
Therefore, if your buffer distances are inside a field, you may use
the "Variable Distance Buffer" algorithm from Processing.
Best regards,
Marco

2016-11-16 1:26 GMT+01:00 Azzurra Lentini :
> Dear all,
>
> I have a shape file with a field called “type”.  In the “type”  field I have
> 4 kinds of samples ( 19 records).
>
> See in the attachment.
>
> The 4 samples are: normal fault, inverse fault, overthrust, syncline.
>
> I would like to create a buffer with different distance for each sample (the
> best it would be to obtain a shape with 5 different buffer distances).
>
> For example  the buffer distance for the sample “ normal fault” is 30 m, for
> the “inverse fault “ is 20 m, for the “overthrust” is 50 m and for the
> “syncline” is 20 m.
>
>
>
> How I can do this kind of buffer??
>
>
>
> Thanks A.L.
>
>
>
>
> --
> Dr. Hydrogeologist
> AZZURRA LENTINI
> Expert of evaluation environmental hazards
> GIS application
> Haity Mobile Tel: 0050946057393
> ++
> Italy Mobile Tel.: **(39) 338 24 40 676
> ++
> SKYPE azzurrahydro
> ++
> azzurralent...@gmail.com
> ++
> *Par respect pour l'environnement,*
>
> *n'imprimez ce mail qu'en cas d'absolue nécessité*
>
>
>
>
>
>
>
> ___
> Qgis-user mailing list
> Qgis-user@lists.osgeo.org
> List info: http://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
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[Qgis-user] different buffer for the same field

[Azzurra Lentini]

Dear all,

I have a shape file with a field called “type”.  In the “type”  field I
have 4 kinds of samples ( 19 records).

See in the attachment.

The 4 samples are: normal fault, inverse fault, overthrust, syncline.

I would like to create a buffer with different distance for each sample
(the best it would be to obtain a shape with 5 different buffer distances).

For example  the buffer distance for the sample “ normal fault” is 30 m,
for the “inverse fault “ is 20 m, for the “overthrust” is 50 m and for the
“syncline” is 20 m.



How I can do this kind of buffer??



Thanks A.L.



-- 
Dr. Hydrogeologist
AZZURRA LENTINI
Expert of evaluation environmental hazards
GIS application
Haity Mobile Tel: 0050946057393
++
Italy Mobile Tel.: **(39) 338 24 40 676
++
SKYPE azzurrahydro
++
azzurralent...@gmail.com
++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*


typeOfFaults.pdf
Description: Adobe PDF document
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