def calculate_svi(
iface, current_layer, project_definition, indicators_operator=None, themes_operator=None, reuse_field=False
):
"""
add an SVI attribute to the current layer
"""
# set default
if indicators_operator is None:
indicators_operator = DEFAULT_COMBINATION
if themes_operator is None:
themes_operator = DEFAULT_COMBINATION
themes = project_definition["children"][1]["children"]
if reuse_field and "svi_field" in project_definition:
svi_attr_name = project_definition["svi_field"]
if DEBUG:
print "Reusing %s" % svi_attr_name
else:
svi_attr_name = "SVI"
svi_field = QgsField(svi_attr_name, QVariant.Double)
svi_field.setTypeName(DOUBLE_FIELD_TYPE_NAME)
attr_names = ProcessLayer(current_layer).add_attributes([svi_field])
svi_attr_name = attr_names[svi_attr_name]
# get the id of the new attribute
svi_attr_id = ProcessLayer(current_layer).find_attribute_id(svi_attr_name)
discarded_feats_ids = []
try:
with LayerEditingManager(current_layer, "Add SVI", DEBUG):
for feat in current_layer.getFeatures():
# If a feature contains any NULL value, discard_feat will
# be set to True and the corresponding SVI will be set to
# NULL
discard_feat = False
feat_id = feat.id()
# init svi_value to the correct value depending on
# themes_operator
if themes_operator in SUM_BASED_COMBINATIONS:
svi_value = 0
elif themes_operator in MUL_BASED_COMBINATIONS:
svi_value = 1
# iterate all themes of SVI
for theme in themes:
indicators = theme["children"]
# init theme_result to the correct value depending on
# indicators_operator
if indicators_operator in SUM_BASED_COMBINATIONS:
theme_result = 0
elif indicators_operator in MUL_BASED_COMBINATIONS:
theme_result = 1
# iterate all indicators of a theme
for indicator in indicators:
if feat[indicator["field"]] == QPyNullVariant(float):
discard_feat = True
discarded_feats_ids.append(feat_id)
break
# For "Average (equal weights)" it's equivalent to use
# equal weights, or to sum the indicators
# (all weights 1)
# and divide by the number of indicators (we use
# the latter solution)
if indicators_operator in (
"Sum (simple)",
"Average (equal weights)",
"Multiplication (simple)",
):
indicator_weighted = feat[indicator["field"]]
else:
indicator_weighted = feat[indicator["field"]] * indicator["weight"]
if indicators_operator in SUM_BASED_COMBINATIONS:
theme_result += indicator_weighted
elif indicators_operator in MUL_BASED_COMBINATIONS:
theme_result *= indicator_weighted
else:
error_message = "invalid indicators_operator: %s" % indicators_operator
raise RuntimeError(error_message)
if discard_feat:
break
if indicators_operator == "Average (equal weights)":
theme_result /= len(indicators)
# combine the indicators of each theme
# For "Average (equal weights)" it's equivalent to use
# equal weights, or to sum the themes (all weights 1)
# and divide by the number of themes (we use
# the latter solution)
if themes_operator in ("Sum (simple)", "Average (equal weights)", "Multiplication (simple)"):
theme_weighted = theme_result
else:
theme_weighted = theme_result * theme["weight"]
if themes_operator in SUM_BASED_COMBINATIONS:
svi_value += theme_weighted
elif themes_operator in MUL_BASED_COMBINATIONS:
svi_value *= theme_weighted
if discard_feat:
svi_value = QPyNullVariant(float)
else:
if themes_operator == "Average (equal weights)":
svi_value /= len(themes)
current_layer.changeAttributeValue(feat_id, svi_attr_id, svi_value)
msg = (
"The SVI has been calculated for fields containing "
"non-NULL values and it was added to the layer as "
"a new attribute called %s"
) % svi_attr_name
iface.messageBar().pushMessage(tr("Info"), tr(msg), level=QgsMessageBar.INFO)
if discarded_feats_ids:
widget = toggle_select_features_widget(
tr("Warning"),
tr("Invalid indicators were found in some features while " "calculating SVI"),
tr("Select invalid features"),
current_layer,
discarded_feats_ids,
current_layer.selectedFeaturesIds(),
)
iface.messageBar().pushWidget(widget, QgsMessageBar.WARNING)
project_definition["indicators_operator"] = indicators_operator
project_definition["themes_operator"] = themes_operator
project_definition["svi_field"] = svi_attr_name
return svi_attr_id, discarded_feats_ids
except TypeError as e:
current_layer.dataProvider().deleteAttributes([svi_attr_id])
msg = "Could not calculate SVI due to data problems: %s" % e
iface.messageBar().pushMessage(tr("Error"), tr(msg), level=QgsMessageBar.CRITICAL)
def calculate_iri(
iface, current_layer, project_definition, svi_attr_id, aal_field_name, discarded_feats_ids, iri_operator=None
):
"""
Copy the AAL and calculate an IRI attribute to the current layer
"""
# set default
if iri_operator is None:
iri_operator = DEFAULT_COMBINATION
aal_weight = project_definition["children"][0]["weight"]
svi_weight = project_definition["children"][1]["weight"]
iri_attr_name = "IRI"
iri_field = QgsField(iri_attr_name, QVariant.Double)
iri_field.setTypeName(DOUBLE_FIELD_TYPE_NAME)
attr_names = ProcessLayer(current_layer).add_attributes([iri_field])
# get the id of the new attributes
iri_attr_id = ProcessLayer(current_layer).find_attribute_id(attr_names[iri_attr_name])
discarded_aal_feats_ids = []
try:
with LayerEditingManager(current_layer, "Add IRI", DEBUG):
for feat in current_layer.getFeatures():
feat_id = feat.id()
svi_value = feat.attributes()[svi_attr_id]
aal_value = feat[aal_field_name]
if aal_value == QPyNullVariant(float) or feat_id in discarded_feats_ids:
iri_value = QPyNullVariant(float)
discarded_aal_feats_ids.append(feat_id)
elif iri_operator == "Sum (simple)":
iri_value = svi_value + aal_value
elif iri_operator == "Multiplication (simple)":
iri_value = svi_value * aal_value
elif iri_operator == "Sum (weighted)":
iri_value = svi_value * svi_weight + aal_value * aal_weight
elif iri_operator == "Multiplication (weighted)":
iri_value = svi_value * svi_weight * aal_value * aal_weight
elif iri_operator == "Average (equal weights)":
# For "Average (equal weights)" it's equivalent to use
# equal weights, or to sum the indices (all weights 1)
# and divide by the number of indices (we use
# the latter solution)
iri_value = (svi_value + aal_value) / 2.0
# store IRI
current_layer.changeAttributeValue(feat_id, iri_attr_id, iri_value)
project_definition["iri_operator"] = iri_operator
# set the field name for the copied AAL layer
project_definition["aal_field"] = aal_field_name
project_definition["iri_field"] = attr_names[iri_attr_name]
msg = (
"The IRI has been calculated for fields containing "
"non-NULL values and it was added to the layer as "
"a new attribute called %s"
) % attr_names[iri_attr_name]
iface.messageBar().pushMessage(tr("Info"), tr(msg), level=QgsMessageBar.INFO)
widget = toggle_select_features_widget(
tr("Warning"),
tr("Invalid values were found in some features while calculating " "IRI"),
tr("Select invalid features"),
current_layer,
discarded_aal_feats_ids,
current_layer.selectedFeaturesIds(),
)
iface.messageBar().pushWidget(widget, QgsMessageBar.WARNING)
return iri_attr_id
except TypeError as e:
current_layer.dataProvider().deleteAttributes([iri_attr_id])
msg = "Could not calculate IRI due to data problems: %s" % e
iface.messageBar().pushMessage(tr("Error"), tr(msg), level=QgsMessageBar.CRITICAL)