The breast cancer Wisconsin (original) dataset is used , and the characteristics of the dataset are as follows:
The training code is as follows. I lost some performance in order to make the code logic clearer during the writing process; although it was tested multiple times, the test set was not randomly selected. . . . Anyway, it's homework, just fool around.
import pandas as pd
import random
import time
# 切分训练集和测试集
def randSplit(data):
n = data.shape[0]
m = int(n * random.uniform(0.1, 0.3))
return data, data.sample(m)
# 构建朴素贝叶斯分类器
def gnb_classify(train, test):
truePro = 0
for i in range(train.shape[0]):
if train.values[i, 10] == 2:
truePro += 1
truePro /= train.shape[0] # true的概率
falsePro = 1 - truePro # false的概率
# 统计频率
numContainer = [{
}, {
}, {
}, {
}, {
}, {
}, {
}, {
}, {
}]
for i in range(train.shape[0]):
if train.values[i, 10] == 2:
for j in range(9):
if train.values[i, j + 1] in numContainer[j]:
numContainer[j][train.values[i, j + 1]] += 1
else:
numContainer[j][train.values[i, j + 1]] = 1
else:
for j in range(9):
if -1 * train.values[i, j + 1] in numContainer[j]:
numContainer[j][-1 * train.values[i, j + 1]] += 1
else:
numContainer[j][-1 * train.values[i, j + 1]] = 1
# 计算概率
for i in numContainer:
sum = 0
for k, v in i.items():
sum += v
for k, v in i.items():
i[k] = v / sum
# 预测训练集
res = 0 # 存储预测正确的数量
for i in range(test.shape[0]):
trueP = truePro
falseP = falsePro
for j in range(9):
if test.values[i, j + 1] in numContainer[j]:
trueP *= numContainer[j][test.values[i, j + 1]]
if -1 * test.values[i, j + 1] in numContainer[j]:
falseP *= numContainer[j][-1 * test.values[i, j + 1]]
if (trueP > falseP and test.values[i, 10] == 2) or (trueP < falseP and test.values[i, 10] == 4):
res += 1
return res / test.shape[0]
# 测试分类器
def test_classify():
sum = 0
for i in range(10):
singleStart = time.time()
randomTrain, randomTest = randSplit(df)
p = gnb_classify(randomTrain, randomTest)
sum += p
singleEnd = time.time()
print("第{}次训练,预测准确率:{} ,训练用时:{}s".format(i + 1, p, singleEnd - singleStart))
return sum / 10
df = pd.read_csv(r'wdbc_discrete.data')
start = time.time()
probability = test_classify()
end = time.time()
print("\n测试集平均准确率为:{}".format(probability))
print("平均训练用时:{}s".format((end - start) / 10))
If you are interested in learning more about it, please visit my personal website: Pupil Space