Want to set the time on a Python Pandas series of datetimes to midnight? Use dt.normalize: You get back series of datetime values, but all times are 00:00:00. The post Pandas dt.normalize: Setting datetime times to midnight appeared first on LernerPython.

Want to convert a Python Pandas datetime column to Unix time (seconds since 1970)? That’s it! No division needed. The post Pandas datetime to Unix time with astype(‘int64’) appeared first on LernerPython.

Want to convert an integer Python Pandas column from Unix time to datetime? Use pd.to_datetime, passing the int column and the “unit” keyword argument, set to “s” (seconds): If the […] The post Convert Unix timestamps to datetime in Pandas with pd.to_datetime appeared first on LernerPython.

Want to check if two Python Pandas datetimes are in the same month/quarter/year? Convert them both to periods, and compare with ==: The post Pandas to_period: Comparing dates by month, quarter, or year appeared first on LernerPython.

Want to find which time period contains a Python Pandas datetime? Use to_period: This returns a Pandas “Period” object, useful (among other things) for checking if two dates are within […] The post Pandas to_period: Finding which period contains a datetime appeared first on LernerPython.

Want to find leap years in a Python Pandas datetime series? Use dt.is_leap_year: The post Find leap years in a Pandas datetime series with dt.is_leap_year appeared first on LernerPython.

Want to know if values in a Python Pandas datetime series are at the start/end of a period? Get a boolean series from: The post Pandas dt.is_month_start: Checking period boundaries in a series appeared first on LernerPython.

Use dt.day_of_week to get the day number from a Python Pandas datetime series. But is 0 Sunday or Monday? Or not used at all? Better: Use the day_name method: Good […] The post `★ Insight ─────────────────────────────────────` appeared first on LernerPython.

Want to grab a part of datetime value in a Python Pandas data frame column? Use “dt”: day_of_week returns an integer, where 0 is Monday and 6 is Sunday. The post Pandas .dt accessor: Extracting year, hour, and day_of_week appeared first on LernerPython.

Reading a CSV into Python Pandas, and parse_dates doesn’t recognize the format? Pass the date_format keyword arg: All strftime codes work! The post pandas read_csv date parsing: Using the date_format keyword appeared first on LernerPython.

If you’re like me, then you’ve lately been exploring agentic coding, having AI write code on your behalf. What will be the impact on our work developing software? On hiring? […] The post Take agentic coding to the next level appeared first on LernerPython.

Reading a CSV into Python Pandas, and want a column to be treated as datetime values? Use parse_dates: Bonus: The PyArrow engine often (not always) parses columns that look like […] The post Pandas parse_dates: Reading CSV date columns as datetimes appeared first on LernerPython.

Want to take a Python Pandas series of strings, and get datetime values? Use pd.to_datetime: Notice: It’s not a method! It’s a top-level pd function. Specify a non-standard “format” with […] The post pd.to_datetime: Converting a pandas string column to datetimes appeared first on LernerPython.

If a Python string contains an ISO-formatted date, skip strptime and use datetime.fromisoformat: The post Parse ISO date strings in Python with datetime.fromisoformat appeared first on LernerPython.

Having a tough time remembering Python strptime vs. strftime? – The “p” (strptime) is for parsing, getting a datetime from a string– The “f” (strftime) is for formatting, getting a […] The post Python strptime vs. strftime: Parsing versus formatting dates appeared first on LernerPython.

Want to parse a Python string into a datetime? Use strptime, passing (a) the string and (b) the date format specification: Both return datetime.datetime(2026, 4, 1, 0, 0) The post Python string to datetime: Parsing dates with strptime appeared first on LernerPython.

Want to format a Python datetime as a string? Use strftime: The post Python datetime formatting: Using strftime for date strings appeared first on LernerPython.

Want a Python datetime with a timezone? Use the “zoneinfo” module: Then pass it to the “tzinfo” keyword arg: The post Timezone-aware datetime objects in Python with zoneinfo appeared first on LernerPython.

Want a Python datetime? Just invoke datetime.datetime: Omitted time units are 0: The post Creating Python datetime objects with datetime.datetime appeared first on LernerPython.

Want to compare two Python datetimes? Just subtract, getting a timedelta: The post Python datetime subtraction: Getting a timedelta between two times appeared first on LernerPython.

Need the current date and time in Python? The post Python current date and time: Using datetime.datetime.now() appeared first on LernerPython.

Generate a Python Pandas DatetimeIndex of datetime values, specifying the frequency, by passing freq and a code: This returns a 184-element DatetimeIndex with evenly-spaced datetime values in that period. The post pandas date_range: Creating a DatetimeIndex with freq appeared first on LernerPython.

Generate a Python Pandas DatetimeIndex of datetime values with pd.date_range: This returns a 10-element series with evenly-spaced datetime values in that period. The post pd.date_range: Evenly spaced Pandas dates with periods appeared first on LernerPython.

Have a Python Pandas series with datetime values, and want all those until now? Compare with pd.Timestamp.now(): This returns the rows from df where the “when” column is before now. The post Pandas datetime filtering: Rows before now with pd.Timestamp.now() appeared first on LernerPython.

Want to check whether a Python Pandas series contains another string? Use .str.contains: This returns a boolean series, whose index matches that of df. Keep only those rows containing ‘a’: The post Pandas .str.contains: Finding and filtering rows by substring appeared first on LernerPython.

Keyword-only parameters in a Python function can have a default: Now call it: Remember: parameters with defaults come *after* those without. The post Python keyword-only parameters: Setting default values appeared first on LernerPython.

Any Python function parameters after *args are keyword-only: Want to give k a value? Use a keyword argument: Don’t need *args? Just use *, and k is keyword only: The post Python keyword-only parameters: Using * and *args in def appeared first on LernerPython.

How to annotate *args in Python? Just set the elements’ type; we know it’s a tuple: Normally, tuples contain different types. In args, we assume all values have the same […] The post Type hints for *args in Python: Annotate the element type appeared first on LernerPython.

Classic use of Python’s *args: Invoke it with separate int arguments: and *not* with a list containing ints: The post Python *args: Collecting positional arguments into a tuple appeared first on LernerPython.

Want your Python function to take any number of positional args? Use *args: – Can be any name, but args is traditional– The * is only in the function definition– […] The post Python *args: Accepting any number of positional arguments appeared first on LernerPython.