Question

import csv
import random
import math

def loadCsv(filename):
    lines = csv.reader(open(filename, "rb"))
    dataset = list(lines)
    for i in range(len(dataset)):
        dataset[i] = [float(x) for x in dataset[i]]
    return dataset

def splitDataset(dataset, splitRatio):
    trainSize = int(len(dataset) * splitRatio)
    trainSet = []
    copy = list(dataset)
    while len(trainSet) < trainSize:
        index = random.randrange(len(copy))
        trainSet.append(copy.pop(index))
    return [trainSet, copy]

def separateByClass(dataset):
    separated = {}
    for i in range(len(dataset)):
        vector = dataset[i]
        if (vector[-1] not in separated):
            separated[vector[-1]] = []
        separated[vector[-1]].append(vector)
    return separated

def mean(numbers):
    return sum(numbers)/float(len(numbers))

def stdev(numbers):
    avg = mean(numbers)
    variance = sum([pow(x-avg,2) for x in numbers])/float(len(numbers)-1)
    return math.sqrt(variance)

def summarize(dataset):
    summaries = [(mean(attribute), stdev(attribute)) for attribute in 
    zip(*dataset)]
    del summaries[-1]
    return summaries

def summarizeByClass(dataset):
    separated = separateByClass(dataset)
    summaries = {}
    for classValue, instances in separated.iteritems():
        summaries[classValue] = summarize(instances)
    return summaries

def calculateProbability(x, mean, stdev):
    exponent = math.exp(-(math.pow(x-mean,2)/(2*math.pow(stdev,2))))
    return (1 / (math.sqrt(2*math.pi) * stdev)) * exponent

def calculateClassProbabilities(summaries, inputVector):
    probabilities = {}
    for classValue, classSummaries in summaries.iteritems():
        probabilities[classValue] = 1
        for i in range(len(classSummaries)):
            mean, stdev = classSummaries[i]
            x = inputVector[i]
            probabilities[classValue] *= calculateProbability(x, mean, stdev)
    return probabilities

def predict(summaries, inputVector):
    probabilities = calculateClassProbabilities(summaries, inputVector)
    bestLabel, bestProb = None, -1
    for classValue, probability in probabilities.iteritems():
        if bestLabel is None or probability > bestProb:
            bestProb = probability
            bestLabel = classValue
    return bestLabel

def getPredictions(summaries, testSet):
    predictions = []
    for i in range(len(testSet)):
        result = predict(summaries, testSet[i])
        predictions.append(result)
    return predictions

def getAccuracy(testSet, predictions):
    correct = 0
    for i in range(len(testSet)):
        if testSet[i][-1] == predictions[i]:
            correct += 1
    return (correct/float(len(testSet))) * 100.0

def main():
    filename = 'processed.cleveland.data.csv'
    splitRatio = 0.67
    dataset = loadCsv(filename)
    trainingSet, testSet = splitDataset(dataset, splitRatio)
    print('Split {0} rows into train={1} and test={2} rows').format(len(dataset), len(trainingSet), len(testSet))
    summaries = summarizeByClass(trainingSet)
    predictions = getPredictions(summaries, testSet)
    accuracy = getAccuracy(testSet, predictions)
    print('Accuracy: {0}%').format(accuracy)

main()

上面的代码是一个朴素的贝叶斯机器学习python脚本。我正在尝试使用存储在processed.cleveland.data.csv中的数据集上的代码。但是，我不断收到以下错误：

Traceback (most recent call last):
File "./naivebayespython.py", line 101, in <module>
main()
File "./naivebayespython.py", line 91, in main
dataset = loadCsv(filename)
File "./naivebayespython.py", line 10, in loadCsv
dataset[i] = [float(x) for x in dataset[i]]
ValueError: could not convert string to float: ?

有人可以告诉我我做错了什么并建议如何解决这个问题？我对Python比较陌生，所以解释也会有所帮助。谢谢！

Answer 1

您可以使用except:和def checkIfFloatable(something): # change the name ;) try: if float(something): return True except: return False def loadCsv(filename): lines = csv.reader(open(filename, "rb")) dataset = list(lines) for i in range(len(dataset)): dataset[i] = [float(x) for x in dataset[i] if checkIfFloatable(x)] # else None return dataset来捕获转化错误但是要知道可以转换的内容 - 请参阅此答案以获取详尽的列表：https://stackoverflow.com/a/20929881/7505395

修改以捕获错误的转化

import React, { Component } from 'react'
import ReactDom from 'react-dom'
import { Icon, Input, Form} from 'antd'

//
import Header from './layout/Header'

// Import Css
import '../css/Home.css'

class Home extends Component {
    render() {
    const { getFieldDecorator } = this.props.form
    return (
      <div>
        <Form>
        {getFieldDecorator('userName', {
          rules: [{ required: true, message: 'Please input your username!' }],
        })(
          <Input prefix={<Icon type="user" style={{ color: 'rgba(0,0,0,.25)' }} />} placeholder="Username" />
        )}
        </Form>
      </div>
    )
  }
}

const WrappedLogin = Form.create()(Home)
ReactDom.render(<WrappedLogin/>, document.getElementById('root'))

export default Home

在终端中运行时python代码中的错误

1 个答案: