# -*- coding: utf-8 -*-
"""
***************************************************************************
vector.py
---------------------
Date : February 2013
Copyright : (C) 2013 by Victor Olaya
Email : volayaf at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
__author__ = 'Victor Olaya'
__date__ = 'February 2013'
__copyright__ = '(C) 2013, Victor Olaya'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'
import csv
from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsFields,
QgsField,
QgsGeometry,
QgsWkbTypes,
QgsFeatureRequest,
QgsPointXY)
def resolveFieldIndex(source, attr):
"""This method takes an object and returns the index field it
refers to in a layer. If the passed object is an integer, it
returns the same integer value. If the passed value is not an
integer, it returns the field whose name is the string
representation of the passed object.
Ir raises an exception if the int value is larger than the number
of fields, or if the passed object does not correspond to any
field.
"""
if isinstance(attr, int):
return attr
else:
index = source.fields().lookupField(attr)
if index == -1:
raise ValueError('Wrong field name')
return index
def values(source, *attributes):
"""Returns the values in the attributes table of a feature source,
for the passed fields.
Field can be passed as field names or as zero-based field indices.
Returns a dict of lists, with the passed field identifiers as keys.
It considers the existing selection.
It assummes fields are numeric or contain values that can be parsed
to a number.
"""
ret = {}
indices = []
attr_keys = {}
for attr in attributes:
index = resolveFieldIndex(source, attr)
indices.append(index)
attr_keys[index] = attr
# use an optimised feature request
request = QgsFeatureRequest().setSubsetOfAttributes(indices).setFlags(QgsFeatureRequest.NoGeometry)
for feature in source.getFeatures(request):
for i in indices:
# convert attribute value to number
try:
v = float(feature.attributes()[i])
except:
v = None
k = attr_keys[i]
if k in ret:
ret[k].append(v)
else:
ret[k] = [v]
return ret
def testForUniqueness(fieldList1, fieldList2):
'''Returns a modified version of fieldList2, removing naming
collisions with fieldList1.'''
changed = True
while changed:
changed = False
for i in range(0, len(fieldList1)):
for j in range(0, len(fieldList2)):
if fieldList1[i].name() == fieldList2[j].name():
field = fieldList2[j]
name = createUniqueFieldName(field.name(), fieldList1)
fieldList2[j] = QgsField(name, field.type(), len=field.length(), prec=field.precision(), comment=field.comment())
changed = True
return fieldList2
def createUniqueFieldName(fieldName, fieldList):
def nextname(name):
num = 1
while True:
returnname = '{name}_{num}'.format(name=name[:8], num=num)
yield returnname
num += 1
def found(name):
return any(f.name() == name for f in fieldList)
shortName = fieldName[:10]
if not fieldList:
return shortName
if not found(shortName):
return shortName
for newname in nextname(shortName):
if not found(newname):
return newname
def findOrCreateField(layer, fieldList, fieldName, fieldLen=24, fieldPrec=15):
idx = layer.fields().lookupField(fieldName)
if idx == -1:
fn = createUniqueFieldName(fieldName, fieldList)
field = QgsField(fn, QVariant.Double, '', fieldLen, fieldPrec)
idx = len(fieldList)
fieldList.append(field)
return (idx, fieldList)
def extractPoints(geom):
points = []
if geom.type() == QgsWkbTypes.PointGeometry:
if geom.isMultipart():
points = geom.asMultiPoint()
else:
points.append(geom.asPoint())
elif geom.type() == QgsWkbTypes.LineGeometry:
if geom.isMultipart():
lines = geom.asMultiPolyline()
for line in lines:
points.extend(line)
else:
points = geom.asPolyline()
elif geom.type() == QgsWkbTypes.PolygonGeometry:
if geom.isMultipart():
polygons = geom.asMultiPolygon()
for poly in polygons:
for line in poly:
points.extend(line)
else:
polygon = geom.asPolygon()
for line in polygon:
points.extend(line)
return points
def combineFields(fieldsA, fieldsB):
"""Create single field map from two input field maps.
"""
fields = []
fields.extend(fieldsA)
namesA = [str(f.name()).lower() for f in fieldsA]
for field in fieldsB:
name = str(field.name()).lower()
if name in namesA:
idx = 2
newName = name + '_' + str(idx)
while newName in namesA:
idx += 1
newName = name + '_' + str(idx)
field = QgsField(newName, field.type(), field.typeName())
fields.append(field)
real_fields = QgsFields()
for f in fields:
real_fields.append(f)
return real_fields
def checkMinDistance(point, index, distance, points):
"""Check if distance from given point to all other points is greater
than given value.
"""
if distance == 0:
return True
neighbors = index.nearestNeighbor(point, 1)
if len(neighbors) == 0:
return True
if neighbors[0] in points:
np = points[neighbors[0]]
if np.sqrDist(point) < (distance * distance):
return False
return True
NOGEOMETRY_EXTENSIONS = [
u'csv',
u'dbf',
u'ods',
u'xlsx',
]
class TableWriter(object):
def __init__(self, fileName, encoding, fields):
self.fileName = fileName
if not self.fileName.lower().endswith('csv'):
self.fileName += '.csv'
self.encoding = encoding
if self.encoding is None or encoding == 'System':
self.encoding = 'utf-8'
with open(self.fileName, 'w', newline='', encoding=self.encoding) as f:
self.writer = csv.writer(f)
if len(fields) != 0:
self.writer.writerow(fields)
def addRecord(self, values):
with open(self.fileName, 'a', newline='', encoding=self.encoding) as f:
self.writer = csv.writer(f)
self.writer.writerow(values)
def addRecords(self, records):
with open(self.fileName, 'a', newline='', encoding=self.encoding) as f:
self.writer = csv.writer(f)
self.writer.writerows(records)