sklearn svm KeyError

Question

我的数据集是一组针对恶意软件和良性软件的系统调用，我对其进行了预处理，现在看起来如下所示

NtQueryPerformanceCounter
NtProtectVirtualMemory
NtProtectVirtualMemory
NtQuerySystemInformation
NtQueryVirtualMemory
NtQueryVirtualMemory
NtProtectVirtualMemory
NtOpenKey
NtOpenKey
NtOpenKey
NtQuerySecurityAttributesToken
NtQuerySecurityAttributesToken
NtQuerySystemInformation
NtQuerySystemInformation
NtAllocateVirtualMemory
NtFreeVirtualMemory

现在，我使用tfidf提取要素，然后使用ngram生成它们的序列

from __future__ import print_function

import numpy as np
import pandas as pd
from time import time
import matplotlib.pyplot as plt

from sklearn import svm, datasets
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.utils import shuffle
from sklearn.svm import OneClassSVM

nGRAM1 = 8
nGRAM2 = 10
weight = 4

main_corpus_MAL = []
main_corpus_target_MAL = []
main_corpus_BEN = []
main_corpus_target_BEN = []

my_categories = ['benign', 'malware']

# feeding corpus the testing data

print("Loading system call database for categories:")
print(my_categories if my_categories else "all")

import glob
import os

malCOUNT = 0
benCOUNT = 0
for filename in glob.glob(os.path.join('C:\\Users\\alika\\Documents\\testingSVM\\sysMAL', '*.txt')):
    fMAL = open(filename, "r")
    aggregate = ""
    for line in fMAL:
        linea = line[:(len(line)-1)]
        aggregate += " " + linea
    main_corpus_MAL.append(aggregate)
    main_corpus_target_MAL.append(1)
    malCOUNT += 1

for filename in glob.glob(os.path.join('C:\\Users\\alika\\Documents\\testingSVM\\sysBEN', '*.txt')):
    fBEN = open(filename, "r")
    aggregate = ""
    for line in fBEN:
        linea = line[:(len(line) - 1)]
        aggregate += " " + linea
    main_corpus_BEN.append(aggregate)
    main_corpus_target_BEN.append(0)
    benCOUNT += 1

# weight as determined in the top of the code
train_corpus = main_corpus_BEN[:(weight*len(main_corpus_BEN)//(weight+1))]
train_corpus_target = main_corpus_target_BEN[:(weight*len(main_corpus_BEN)//(weight+1))]
test_corpus = main_corpus_MAL[(len(main_corpus_MAL)-(len(main_corpus_MAL)//(weight+1))):]
test_corpus_target = main_corpus_target_MAL[(len(main_corpus_MAL)-len(main_corpus_MAL)//(weight+1)):]

def size_mb(docs):
    return sum(len(s.encode('utf-8')) for s in docs) / 1e6

# size of datasets
train_corpus_size_mb = size_mb(train_corpus)
test_corpus_size_mb = size_mb(test_corpus)

print("%d documents - %0.3fMB (training set)" % (
    len(train_corpus_target), train_corpus_size_mb))
print("%d documents - %0.3fMB (test set)" % (
    len(test_corpus_target), test_corpus_size_mb))
print("%d categories" % len(my_categories))
print()
print("Benign Traces: "+str(benCOUNT)+" traces")
print("Malicious Traces: "+str(malCOUNT)+" traces")
print()

print("Extracting features from the training data using a sparse vectorizer...")
t0 = time()

vectorizer = TfidfVectorizer(ngram_range=(nGRAM1, nGRAM2), min_df=1, use_idf=True, smooth_idf=True) ##############

analyze = vectorizer.build_analyzer()

X_train = vectorizer.fit_transform(train_corpus)

duration = time() - t0
print("done in %fs at %0.3fMB/s" % (duration, train_corpus_size_mb / duration))
print("n_samples: %d, n_features: %d" % X_train.shape)
print()

print("Extracting features from the test data using the same vectorizer...")
t0 = time()
X_test = vectorizer.transform(test_corpus)
duration = time() - t0
print("done in %fs at %0.3fMB/s" % (duration, test_corpus_size_mb / duration))
print("n_samples: %d, n_features: %d" % X_test.shape)
print()

输出为：

Loading system call database for categories:
['benign', 'malware']
177 documents - 45.926MB (training set)
44 documents - 12.982MB (test set)
2 categories

Benign Traces: 72 traces
Malicious Traces: 150 traces

Extracting features from the training data using a sparse vectorizer...
done in 7.831695s at 5.864MB/s
n_samples: 177, n_features: 603170

Extracting features from the test data using the same vectorizer...
done in 1.624100s at 7.993MB/s
n_samples: 44, n_features: 603170

现在对于学习部分，我尝试使用sklearn OneClassSVM

print("==================\n")
print("Training: ")
classifier = OneClassSVM(kernel='linear', gamma='auto')
classifier.fit(X_test)

fraud_pred = classifier.predict(X_test)

unique, counts = np.unique(fraud_pred, return_counts=True)
print (np.asarray((unique, counts)).T)

fraud_pred = pd.DataFrame(fraud_pred)
fraud_pred= fraud_pred.rename(columns={0: 'prediction'})
main_corpus_target = pd.DataFrame(main_corpus_target)
main_corpus_target= main_corpus_target.rename(columns={0: 'Category'})

这是fraud_pred和main_corpus_target的输出

prediction
0   1
1  -1
2   1
3   1
4   1
5  -1
6   1
7  -1
...
30 rows * 1 column
====================
Category
0   1
1   1
2   1
3   1
4   1
...
217 0
218 0
219 0
220 0
221 0
222 rows * 1 column

但是当我尝试计算TP,TN,FP,FN时

##Performance check of the model

TP = FN = FP = TN = 0
for j in range(len(main_corpus_target)):
    if main_corpus_target['Category'][j]== 0 and fraud_pred['prediction'][j] == 1:
        TP = TP+1
    elif main_corpus_target['Category'][j]== 0 and fraud_pred['prediction'][j] == -1:
        FN = FN+1
    elif main_corpus_target['Category'][j]== 1 and fraud_pred['prediction'][j] == 1:
        FP = FP+1
    else:
        TN = TN +1
print (TP,  FN,  FP,  TN)

我得到了这个错误：

KeyError                                  Traceback (most recent call last)
<ipython-input-32-1046cc75ba83> in <module>
      7     elif main_corpus_target['Category'][j]== 0 and fraud_pred['prediction'][j] == -1:
      8         FN = FN+1
----> 9     elif main_corpus_target['Category'][j]== 1 and fraud_pred['prediction'][j] == 1:
     10         FP = FP+1
     11     else:

c:\users\alika\appdata\local\programs\python\python36\lib\site-packages\pandas\core\series.py in __getitem__(self, key)
   1069         key = com.apply_if_callable(key, self)
   1070         try:
-> 1071             result = self.index.get_value(self, key)
   1072 
   1073             if not is_scalar(result):

c:\users\alika\appdata\local\programs\python\python36\lib\site-packages\pandas\core\indexes\base.py in get_value(self, series, key)
   4728         k = self._convert_scalar_indexer(k, kind="getitem")
   4729         try:
-> 4730             return self._engine.get_value(s, k, tz=getattr(series.dtype, "tz", None))
   4731         except KeyError as e1:
   4732             if len(self) > 0 and (self.holds_integer() or self.is_boolean()):

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_value()

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_value()

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

KeyError: 30

1)我知道错误是因为它试图访问字典中没有的键，但我不能只在fraud_pred中插入一些数字来处理这个问题，有什么建议吗？

2)我是不是做错了什么，它们不匹配？

3)我想将结果与其他一类分类算法进行比较，由于我的方法，我可以使用的最好的算法是什么？

Answer 1

编辑:计算指标前：

您可以将拟合和预测函数更改为：

fraud_pred = classifier.fit_predict(X_test)

另外，你的main_corpus_target和X_test应该有相同的长度，你能把代码放在你创建main_corpus_target的地方吗？

它是在benCOUNT += 1之后创建的：main_corpus_target = main_corpus_target_MAL main_corpus_target.extend(main_corpus_target_BEN)

这意味着您正在创建一个包含MAL和BEN的main_corpus_target，并且您得到的错误是：

ValueError: Found input variables with inconsistent numbers of samples: [30, 222]

fraud_pred的样本数是30，所以您应该用一个30的数组来计算它们。main_corpus_target包含222。

观察您的代码，我看到您想要计算与test_corpus X_test = vectorizer.transform(test_corpus)相关的X_test。最好将结果与test_corpus_target进行比较，后者是数据集的目标变量，长度也是30。您拥有的这两行应该输出相同的长度：

test_corpus = main_corpus_MAL[(len(main_corpus_MAL)-(len(main_corpus_MAL)//(weight+1))):]
test_corpus_target = main_corpus_target_MAL[(len(main_corpus_MAL)-len(main_corpus_MAL)//(weight+1)):]

我能问你为什么要计算TP，TN..。就你一个人？

你有一个更快的选择：

1. 转换fraud_pred系列，将-1替换为0。
2. 使用sklearn offers的混淆矩阵函数。
3. 使用ravel提取混淆矩阵的值。

例如，将-1转换为0后：

from sklearn.metrics import confusion_matrix
tn, fp, fn, tp = confusion_matrix(fraud_pred, main_corpus_target['Category'].values).ravel()

另外，如果您使用的是pandas的最新版本：

from sklearn.metrics import confusion_matrix
tn, fp, fn, tp = confusion_matrix(fraud_pred, main_corpus_target['Category'].to_numpy()).ravel()