Tag: Pandas
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AI seminars — just one of the big changes at LernerPython
July and August are often when people take a break or go on vacation. But for me, this summer has been super busy, full of writing and improving LernerPython based on feedback I’ve gotten from people around the world. And so, I’m here with some big changes I’m making at LernerPython World Headquarters: 1. AI…
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Free real-world Pandas exercises, with solutions
If you want to get better at Pandas, the hard part isn’t finding tutorials. It’s finding problems worth solving. Most exercises hand you a tidy little table of five rows and ask you to sum a column — which teaches you the syntax, but nothing about the job. For the last 3.5 years, I’ve written…
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New: In-browser Python/Pandas/Git exercises, with AI support
Over my 30+ years teaching Python, I’ve included practice exercises in all of my courses. And when I started to teach Git and Pandas, I made sure to include practice exercises there, too. That’s because there’s no learning without practice. At least, there’s no effective learning. Frustration isn’t fun, but it’s a necessary part of…
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Python dict keys must be hashable: Why lists don’t work
You can’t use a list as a Python dict key: Why not? Dicts run “hash” on a key to choose a pair’s storage location. To avoid pairs getting lost, mutable builtins (list, set, dict) cannot be used as dict keys.
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Pandas str.split: Get the first item of a comma-separated column
A Python Pandas column contains comma-separated values. How can you get the first of those? First, break each string into a list: Then use .str[0] to grab the first element from the resulting list:
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Pandas str.isdigit: Checking whether strings contain only digits
Want to check whether a Python Pandas string series only contains digits? Use str.isdigit: This returns a boolean series, with df’s index. You can then convert the digit-containing strings to integers:
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Pandas string slicing: Extracting substrings with .str.slice
Want to retrieve a slice from a string column in your Python Pandas data frame? Use .str.slice:
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Pandas .str.get: Retrieving characters from string columns
Want to retrieve from a string column in your Python Pandas data frame? Use .str.get: But wait: You can use [], in place of .get:
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Pandas MultiIndex: Dropping a level with reset_index(drop=True)
Your Python Pandas data frame has a multi-index, and you want to remove one part — not return it to be a regular column? Add drop=True:
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Pandas reset_index: Moving multi-index levels back to columns
Your Python Pandas data frame has a multi-index? Return selected parts to columns with the “level” keyword argument: