Python 3 for f, b in zip(foo, bar): print(f, b) zip stops when the shorter of foo or bar stops. In Python 3, zip returns an iterator of tuples, like itertools.izip in Python2. To get a list of tuples, use list(zip(foo, bar)). And to zip until both iterators are exhausted, you would use itertools.zip_longest. Python … Read more
I routinely use tens of gigabytes of data in just this fashion e.g. I have tables on disk that I read via queries, create data and append back. It’s worth reading the docs and late in this thread for several suggestions for how to store your data. Details which will affect how you store your … Read more
There’s a function that returns exactly what you want import os print(os.path.basename(your_path)) WARNING: When os.path.basename() is used on a POSIX system to get the base name from a Windows-styled path (e.g. “C:\\my\\file.txt”), the entire path will be returned. Example below from interactive python shell running on a Linux host: Python 3.8.2 (default, Mar 13 2020, … Read more
help(‘modules’) in a Python shell/prompt.
The effects of the three different methods to remove an element from a list: remove removes the first matching value, not a specific index: >>> a = [0, 2, 3, 2] >>> a.remove(2) >>> a [0, 3, 2] del removes the item at a specific index: >>> a = [9, 8, 7, 6] >>> del … Read more
This will convert the dict_keys object to a list: list(newdict.keys()) On the other hand, you should ask yourself whether or not it matters. It is Pythonic to assume duck typing — if it looks like a duck and it quacks like a duck, it is a duck. The dict_keys object can be iterated over just … Read more
My quick & dirty JSON dump that eats dates and everything: json.dumps(my_dictionary, indent=4, sort_keys=True, default=str) default is a function applied to objects that aren’t serializable. In this case it’s str, so it just converts everything it doesn’t know to strings. Which is great for serialization but not so great when deserializing (hence the “quick & … Read more
For whitespace on both sides, use str.strip: s = ” \t a string example\t ” s = s.strip() For whitespace on the right side, use str.rstrip: s = s.rstrip() For whitespace on the left side, use str.lstrip: s = s.lstrip() You can provide an argument to strip arbitrary characters to any of these functions, like … Read more
For Python 2.6 and later and Python 3.x: except Exception as e: print(e) For Python 2.5 and earlier, use: except Exception,e: print str(e)
str.count(sub[, start[, end]]) Return the number of non-overlapping occurrences of substring sub in the range [start, end]. Optional arguments start and end are interpreted as in slice notation. >>> sentence=”Mary had a little lamb” >>> sentence.count(‘a’) 4