pythonpandasdatetimevalueerror

Python Date Time missing month but it is there


I've been trying to create this machine learning tool to make predictions on the amount of orders in the next year per month but I have been getting this error:

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

here is my code. I am passing in the month and it should be getting assigned a number that is supposed to represent the respective month, but form some reason this does not appear to be happening. I am also aware that the months are not all capitalized but this should not be an issue as they are all getting passed to lowercase.

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)

Solution

  • If you check to_datetime documentation, you will find that it requires the column called month. Your month column contains the month names.

    You should rename the columns before using to_datetime like this: df=df.rename(columns={"Month": "MonthName", "MonthNum": "Month"}). This way, pandas will look for the month numeric column and find it.