CODEWITHSUNDEEP
pythonpandasdataframedatetime-format
ricenix
ricenix

Reputation: 21

pd.to_datetime does not convert object to datetime

My current dataset is as follows:

cleaned_df dataset

Data type of dataset

To provide more details to my column headers, I renamed the headers as follows: cleaned_df.rename(columns={'month':'yyyy_mm','no_of_rainy_days':'no_of_rainy_days (days)', 'total_rainfall':'total_rainfall (mm)', 'mean_rh':'monthly_mean_humidity (%)', 'mean_sunshine_hrs':'mean_sunshine_hrs (hr)', 'cpi':'consumer_price_index (%)'})

As seen in image 2, my month column is of an object data type and I would like to convert it to a datetime64[ns] format.

I tried the following code: cleaned_df['month'] = pd.to_datetime(cleaned_df['month']).dt.strftime('%Y-%m') and it gives me the format of YYYY-MM as I wanted - image 1.

However, when i checked its information again, it still shows as an object. Additionally, the code throws a warning: /var/folders/90/274n3kt55bl4fjg8t134196r0000gn/T/ipykernel_841/3350504036.py:2: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy cleaned_df['month'] = pd.to_datetime(cleaned_df['month']).dt.strftime('%Y-%m')

How do I properly code this according to best practice and to ensure the object gets converted?

Upvotes: 1

Views: 1146

Answers (1)

Panda Kim
Panda Kim

Reputation: 13267

Example Code

s = pd.Series(['2020-01', '2020-02'])

s

0    2020-01
1    2020-02
dtype: object <-- chk dtype

Step 1

pd.to_datetime : convert datetime 64[ns]

pd.to_datetime(s)

result:

0   2020-01-01
1   2020-02-01
dtype: datetime64[ns] <-- chk dtype

Step2

dt.strftime(format): convert datetime to string in given format

pd.to_datetime(s).dt.strftime('%Y-%m')

result:

0    2020-01
1    2020-02
dtype: object <-- chk dtype



It's not that code you changed doesn't apply, it comes out as you changed.

Your code is converting str(object) to datetime and then back to str(object).

Upvotes: 1

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