Python 日期时间缺少月份，但它在那里

Question

我一直在尝试创建这个机器学习工具来预测明年每月的订单量，但我一直收到此错误：

ValueError: to assemble mappings requires at least that [year, month, day] be specified: [month] is missing

这是我的代码。我正在传递月份，应该为它分配一个代表相应月份的数字，但出于某种原因，这似乎没有发生。我还知道月份并非全部大写，但这不应该是问题，因为它们都转为小写。

import pandas as pd

# Example DataFrame creation from CSV (replace this with your actual CSV upload logic)
data = {
    'Year': [2021, 2021, 2021, 2022, 2022, 2023, 2023],
    'Month': ['january', 'february', 'march', 'january', 'february', 'march', 'april'],
    'OrderCount': [60, 55, 70, 64, 56, 76, 70]
}
df = pd.DataFrame(data)

# Convert 'Month' to numerical values (January = 1, February = 2, etc.)
month_map = {
    'january': 1, 'february': 2, 'march': 3, 'april': 4, 'may': 5, 'june': 6,
    'july': 7, 'august': 8, 'september': 9, 'october': 10, 'november': 11, 'december': 12
}

# Map month names to numbers
df['Month'] = df['Month'].str.lower()
df['MonthNum'] = df['Month'].map(month_map)

# Convert Year and MonthNum to integers
df['Year'] = df['Year'].astype(int)
df['MonthNum'] = df['MonthNum'].astype(int)

# Combine Year and Month into a DateTimeIndex
# The next line is where the issue is likely occurring
df['Date'] = pd.to_datetime(df[['Year', 'MonthNum']].assign(DAY=1))

# Print the resulting DataFrame to see if 'Date' was successfully created
print(df)

Answer 1

如果您检查 to_datetime 文档，您会发现它需要名为

month

的列。您的

month

列包含月份名称。

您应该在使用

to_datetime

之前重命名列，如下所示：

df=df.rename(columns={"Month": "MonthName", "MonthNum": "Month"})

。这样，pandas 就会寻找

month

数字列并找到它。