Category: Python
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Pandas loc vs iloc slicing: Inclusive vs exclusive endpoints
When retrieving a slice with loc in Python Pandas, the end point is included, highly unusual in Python!
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pandas read_csv: Speed up loading with the PyArrow engine
Reading a CSV file into a Python Pandas data frame? Speed things up by specifying the PyArrow engine. Data storage isn’t affected. With a 2.2GB file, it took 4s vs. 55s — more than 10x faster!
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Pandas category dtype: Reduce string column memory by 90%
Does your Python Pandas column contain repeated strings? Turn it into a ‘category’ series (like an enum) to save memory: That’s right — 90% less memory!
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Python multi-line comprehensions: Formatting for readability
Make your Python comprehensions easier to read, write, and debug with multiple lines. # better than:[n**2 for n in range(10) if n%2]
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collections.Counter: Counting values in a Python sequence
Want to count values in a Python sequence? Use Counter: Bonus: Counter inherits from dict, getting its methods + operators.
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OrderedDict vs dict: Why equality checks compare order
Why use OrderedDict if Python dicts are now ordered? Because equality checks order too:
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Sorting custom Python objects with __lt__ and __eq__
Make a Python class sortable with __lt__ and __eq__:
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Python str.strip: Removing any characters, not just whitespace
By default, str.strip in Python removes leading/trailing whitespace: It takes an optional argument, naming leading/trailing characters to remove. Great for cleaning strings:
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Dispatch tables in Python: Replace if/elif with a dict of functions
Instead of choosing which Python function to run with if/elif/else, use a dispatch table — a dict with functions as values:
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Python dict insertion order: What happens when you re-add a key
Modern Python dicts remember insertion order: This applies in for loops, too!