Added stdev

qgis · Jan 16, 2015 · fe37600 · fe37600
1 parent 98a7242
commit fe37600
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Showing 3 changed files with 44 additions and 10 deletions.
diff --git a/python/plugins/fTools/tools/doPointsInPolygon.py b/python/plugins/fTools/tools/doPointsInPolygon.py
@@ -31,6 +31,7 @@
 from PyQt4.QtCore import *
 from PyQt4.QtGui import *
 import ftools_utils
+import math
 from qgis.core import *
 from ui_frmPointsInPolygon import Ui_Dialog
 
@@ -207,8 +208,8 @@ def run(self):
             columnName = unicode(item.text() + "_" + self.statistics)
             index = polyProvider.fieldNameIndex(unicode(columnName))
             if index == -1:
-                if item.type() == typeDouble or self.statistics == "mean":
-                    fieldList.append( QgsField(columnName, QVariant.Double, "double", 10, 2,  "Value") )
+                if item.type() == typeDouble or self.statistics == "mean" or self.statistics == "stddev":
+                    fieldList.append( QgsField(columnName, QVariant.Double, "double", 24, 15,  "Value") )
                 else:
                     fieldList.append( QgsField(columnName, QVariant.Int, "int", 10, 0,  "Value") )
 
@@ -268,6 +269,16 @@ def run(self):
                 # Compute the statistical values for selected vector attributes
                 for item in selectedItems:
                     values = valueList[item.text()]
+                    # Check if the input contains non-numeric values
+                    non_numeric_values = False
+                    for value in values:
+                        if (isinstance(value,  type(float())) != True) and (isinstance(value,  type(int())) != True):
+                            non_numeric_values = True
+                            break
+                    # Jump over invalid values
+                    if non_numeric_values is True:
+                        continue
+
                     if values and len(values) > 0:
                         if self.statistics == "sum":
                             value = reduce(myAdder,  values)
@@ -279,6 +290,9 @@ def run(self):
                         elif self.statistics == "max":
                             values.sort()
                             value = values[-1]
+                        elif self.statistics == "stddev":
+                            value = two_pass_variance(values)
+                            value = math.sqrt(value)
                         atMap.append(value)
 
             outFeat.setAttributes(atMap)
@@ -309,3 +323,27 @@ def stop(self):
 
 def myAdder(x,y): 
     return x+y
+
+def two_pass_variance(data):
+    """
+    Variance algorithm taken from Wikipedia:
+    https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance
+    """
+    n    = 0.0
+    sum1 = 0.0
+    sum2 = 0.0
+
+    for x in data:
+        n    = n + 1.0
+        sum1 = sum1 + float(x)
+
+    if (n < 2):
+        return 0
+
+    mean = sum1 / n
+
+    for x in data:
+        sum2 = sum2 + (x - mean)*(x - mean)
+
+    variance = sum2 / (n - 1)
+    return variance
diff --git a/python/plugins/fTools/tools/doVectorGrid.py b/python/plugins/fTools/tools/doVectorGrid.py
@@ -264,7 +264,6 @@ def compute( self, bound, xOffset, yOffset, polygon ):
                     pt4 = QgsPoint(x, y - yOffset)
                     pt5 = QgsPoint(x, y)
 
-                    print self.angle.value()
                     if self.angle.value() != 0.0:
                         self.rotatePoint(pt1)
                         self.rotatePoint(pt2)

diff --git a/python/plugins/fTools/tools/frmVectorGrid.ui b/python/plugins/fTools/tools/frmVectorGrid.ui
@@ -205,7 +205,7 @@
          <number>10</number>
         </property>
         <property name="minimum">
-         <double>0.000001000000000</double>
+         <double>0.000100000000000</double>
         </property>
         <property name="maximum">
          <double>1000000000.000000000000000</double>
@@ -270,7 +270,7 @@
          <number>10</number>
         </property>
         <property name="minimum">
-         <double>0.000001000000000</double>
+         <double>0.000100000000000</double>
         </property>
         <property name="maximum">
          <double>1000000000.000000000000000</double>
@@ -286,7 +286,7 @@
          <string>Output grid as polygons</string>
         </property>
         <property name="checked">
-         <bool>true</bool>
+         <bool>false</bool>
         </property>
        </widget>
       </item>
@@ -296,7 +296,7 @@
          <string>Output grid as lines</string>
         </property>
         <property name="checked">
-         <bool>false</bool>
+         <bool>true</bool>
         </property>
        </widget>
       </item>
@@ -369,9 +369,6 @@
      <property name="text">
       <string>Add result to canvas</string>
      </property>
-     <property name="checked">
-      <bool>true</bool>
-     </property>
     </widget>
    </item>
    <item row="6" column="0">