From 220cca2397f416aafdf5752a3eb2b1a9cd64e37e Mon Sep 17 00:00:00 2001
From: Tobias Schmidt <tobias.schmidt@unibas.ch>
Date: Thu, 1 Dec 2011 16:06:28 +0100
Subject: [PATCH] fix bug in roc code:
roc code returns None if no true positives are found
(otherwise this leads to a division by zero)
---
modules/base/pymod/table.py | 20 ++++++++++++++++----
modules/base/tests/test_table.py | 23 +++++++++++++++++++++--
2 files changed, 37 insertions(+), 6 deletions(-)
diff --git a/modules/base/pymod/table.py b/modules/base/pymod/table.py
index 87a425ebc..fa76ceaed 100644
--- a/modules/base/pymod/table.py
+++ b/modules/base/pymod/table.py
@@ -1252,6 +1252,11 @@ class Table:
fp += 1
x.append(fp)
y.append(tp)
+
+ # if no false positives or false negatives values are found return None
+ if x[-1]==0 or y[-1]==0:
+ return None
+
x = [float(v)/x[-1] for v in x]
y = [float(v)/y[-1] for v in y]
return x,y
@@ -1265,10 +1270,12 @@ class Table:
try:
import numpy as np
- rocx, rocy = self.ComputeROC(score_col, class_col, score_dir,
- class_dir, class_cutoff)
+ roc = self.ComputeROC(score_col, class_col, score_dir,
+ class_dir, class_cutoff)
- return np.trapz(rocy, rocx)
+ if not roc:
+ return None
+ return np.trapz(roc[1], roc[0])
except ImportError:
LogError("Function needs numpy, but I could not import it.")
raise
@@ -1284,9 +1291,14 @@ class Table:
try:
import matplotlib.pyplot as plt
- enrx, enry = self.ComputeROC(score_col, class_col, score_dir,
+ roc = self.ComputeROC(score_col, class_col, score_dir,
class_dir, class_cutoff)
+ if not roc:
+ return None
+
+ enrx, enry = roc
+
if not title:
title = 'ROC of %s'%score_col
diff --git a/modules/base/tests/test_table.py b/modules/base/tests/test_table.py
index 4220de12f..e2a3060c6 100644
--- a/modules/base/tests/test_table.py
+++ b/modules/base/tests/test_table.py
@@ -985,7 +985,15 @@ class TestTable(unittest.TestCase):
img1 = Image.open(os.path.join("testfiles","roc-out.png"))
img2 = Image.open(os.path.join("testfiles","roc.png"))
self.CompareImages(img1, img2)
- #pl.show()
+
+ # no true positives
+ tab = Table(['classific', 'score'], 'bf',
+ classific=[False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False],
+ score=[0.9, 0.8, 0.7, 0.6, 0.55, 0.54, 0.53, 0.52, 0.51, 0.505, 0.4, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.30, 0.1])
+ pl = tab.PlotROC(score_col='score', score_dir='+',
+ class_col='classific',
+ save=os.path.join("testfiles","roc-out.png"))
+ self.assertEquals(pl, None)
def testPlotROCSameValues(self):
if not HAS_MPL or not HAS_PIL:
@@ -1011,7 +1019,14 @@ class TestTable(unittest.TestCase):
auc = tab.ComputeROCAUC(score_col='score', score_dir='+', class_col='classific')
self.assertAlmostEquals(auc, auc_ref)
- def testCalcROC(self):
+ # no true positives
+ tab = Table(['classific', 'score'], 'bf',
+ classific=[False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False],
+ score=[0.9, 0.8, 0.7, 0.6, 0.55, 0.54, 0.53, 0.52, 0.51, 0.505, 0.4, 0.39, 0.38, 0.37, 0.36, 0.35, 0.34, 0.33, 0.30, 0.1])
+ auc = tab.ComputeROCAUC(score_col='score', score_dir='+', class_col='classific')
+ self.assertEquals(auc, None)
+
+ def testCalcROCAUCWithCutoff(self):
if not HAS_NUMPY:
return
tab = Table(['classific', 'score'], 'ff',
@@ -1020,6 +1035,10 @@ class TestTable(unittest.TestCase):
auc = tab.ComputeROCAUC(score_col='score', class_col='classific', class_cutoff=0.5)
self.assertEquals(auc, 1.0)
+ # no true positives
+ auc = tab.ComputeROCAUC(score_col='score', class_col='classific', class_cutoff=1.0)
+ self.assertEquals(auc, None)
+
def testCalcROCFromFile(self):
tab = Table.Load(os.path.join('testfiles','roc_table.dat'))
auc = tab.ComputeROCAUC(score_col='prediction', class_col='reference', class_cutoff=0.4)
--
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