Question

所以我有一个csv文件，我必须从中找到按类别分组的所有产品的平均价格。我设法将文件中的所有行放入列表中。现在我试着这个：

FILE_NAME = 'catalog_sample.csv'
full_catalog = []

with open(FILE_NAME, encoding='utf-8') as file:
    for line in file:            
        one_record = line.split(',')
        full_catalog.append(one_record)

category_dict = {}
prices = []

for i in full_catalog:
    if str(i[-2]) not in category_dict:
        category_name = str(i[-2])
        category_dict[category_name] = float(i[-1])
    else:
        prices.append(float(i[-1]))

到目前为止，我收到了一个字典，其中包含文件中的所有类别作为键，但该值是文件中第一次出现该键的价格：

'Men': 163.99
'Women': 543.99

似乎＆＃34;否则＆＃34;因为我期待（为键添加值）不起作用。有什么建议？谢谢！

Answer 1

我建议您在浏览文件时创建字典，而不是将它们添加到列表中，然后通过它来构建字典。

class WizardForm extends Component {
  constructor(props) {
    super(props)
    this.nextPage = this.nextPage.bind(this)
    this.previousPage = this.previousPage.bind(this)
    this.state = {
      page: 1
    }
  }

  nextPage() {
    this.setState({ page: this.state.page + 1 })
  }

  previousPage() {
    this.setState({ page: this.state.page - 1 })
  }

  render() {
    const { onSubmit } = this.props
    const { page } = this.state
    return (<div>
        {page === 1 && <WizardFormFirstPage onSubmit={this.nextPage}/>}
        {page === 2 && <WizardFormSecondPage previousPage={this.previousPage} onSubmit={this.nextPage}/>}
        {page === 3 && <WizardFormThirdPage previousPage={this.previousPage} onSubmit={onSubmit}/>}
      </div>
    )
  }
}

编辑：已修复以匹配提供的行格式。如果您仍需要整个列表

，则已包含

category_dict = {}
full_catalog = []

with open(FILE_NAME, encoding='utf-8') as file:
    for line in file:
        item = line.split(',')
        # Unpack the last 2 items from list
        category = item[-2].strip()
        price = float(item[-1])

        # Try get the list of prices for the category
        # If there is no key matching category in dict
        # Then return an empty list
        prices = category_dict.get(category, [])
        # Append the price to the list
        prices.append(price)

        # Set the list as the value for the category
        # If there was no key then a key is created
        # The value is the list with the new price
        category_dict[category] = prices
        full_catalog.append(item)

如何在字典中为键中的键添加值？蟒蛇

1 个答案: