英文:
How to combine pandas, dataclasses to import data
问题
我正在尝试使用dataclasses学习类
@dataclass
class Collect:
url : str
def collect(url):
df = pd.read_csv(url)
return df
df = Collect("national_news_scrape.csv")
df.head()
但是我遇到了错误：
AttributeError: 'Collect'对象没有'head'属性
不太清楚为什么。
英文:
I'm trying to learn classes with dataclasses
@dataclass
class Collect:
url : str
def collect(url):
df = pd.read_csv(url)
return df
df = Collect("national_news_scrape.csv")
df.head()
But I get error:
AttributeError: 'Collect' object has no attribute 'head'
Not sure why.
答案1
得分: 1
以下是示例：
@dataclass
class Collect:
url: str
def collect(self):
df = pd.read_csv(self.url)
return df
# 创建一个 Collect 类的实例
instance = Collect("national_news_scrape.csv")
print(instance.url) # national_news_scrape.csv
# 调用 Collect 类的方法
df = instance.collect()
print(df.head())
英文:
Here is an example:
@dataclass
class Collect:
url: str
def collect(self):
df = pd.read_csv(self.url)
return df
# create an instance of Collect class
instance = Collect("national_news_scrape.csv")
print(instance.url) # national_news_scrape.csv
# call the method of Collect class
df = instance.collect()
print(df.head())
答案2
得分: 1
问题的原因
你收到AttributeError是因为你的代码构造了Collect对象，并使用了Collect("national_news_scrape.csv")，但是没有调用collect()方法来返回一个pandas的DataFrame。
head()方法是在DataFrame实例上定义的，而不是在你的Collect类的实例上。
修复方法
然而，我感到有些混淆！我会假设你的代码是一个_最小(不-)工作示例_，这解释了为什么你在这里使用了@dataclass，当它似乎不是必要的时候。
Danila发布了一些有效的代码，尽管我自己没有测试过 - 请查看这个答案以获取修正。
此外，请注意collect()方法的签名变化 - 现在不再需要一个url位置参数，因为它使用了由构造函数从@dataclasss设置的self.url实例属性。
英文:
The cause
You are getting the AttributeError because your code constructs the Collect object with Collect("national_news_scrape.csv"), but does not then call the collect() method to return a pandas DataFrame.
The head() method is defined on a DataFrame instance and not an instance of your Collect class.
The fix
I do however sense some confusion! I will assume that your code is a Minimal (non-)Working Example, which would explain why you are using @dataclass here when it doesn't seem necessary.
Danila has posted some working code, though I haven't tested it myself - please consult this answer for a correction.
Additionally, please note the change in signature of the collect() method - it now no longer requires a url positional argument because it uses the self.url instance attribute that is set by the constructor from @dataclasss.
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