Search results
Use the Enumerate Function. Python's enumerate function reduces the visual clutter by hiding the accounting for the indexes, and encapsulating the iterable into another iterable (an enumerate object) that yields a two-item tuple of the index and the item that the original iterable would provide. That looks like this:
Mar 4, 2014 · The enumerate() function adds a counter to an iterable.. So for each element in cursor, a tuple is produced with (counter, element); the for loop binds that to row_number and row, respectively.
Apr 28, 2015 · Now available on Stack Overflow for Teams! AI features where you work: search, IDE, and chat. Learn more Explore Teams
Mar 27, 2016 · It's basically too much code; and potentially yields the wrong answer. Using enumerate with a dict is potentially dangerous. Python does not guarantee key order when using enumerate; it is potentially possible for keys to be emitted in a different order on subsequent runs. @roadrunner66's answer is the most correct solution. –
Jul 1, 2015 · So the complexity should be: Initialization: O (1) Returning the next element: O (1) Returning all elements: n * O (1) Please note that enumerate does NOT create a new data structure (list of tuples or something like that)! It is just iterating over the existing list, keeping the element index in mind. You can try this out by yourself:
Feb 10, 2009 · How do I traverse a list in reverse order in Python? So I can start from collection[len(collection)-1] and end in collection[0]. I also want to be able to access the loop index.
Building on the answer by @unutbu, I have compared the iteration performance of two identical lists when using Python 3.6's zip() functions, Python's enumerate() function, using a manual counter (see count() function), using an index-list, and during a special scenario where the elements of one of the two lists (either foo or bar) may be used to index the other list.
In Python, the above equation can be written like this: # Calculate and return a new value, `val`, by performing the following equation: val = ( 2 * A_i_minus_2 + 3 * A_i_minus_1 + 4 * A + 5 * A_i_plus_1 # Python ternary operator; don't forget parentheses around the entire # ternary expression!
Jan 17, 2010 · Take @Alok's advice and use enumerate() for files which could be very large, and won't fit into memory. Note that using this method might slow because the file is read sequentially. Note that using this method might slow because the file is read sequentially.
Nov 25, 2015 · I've been told that there's an enumerate() function that can take care of the "i" variable for me: for i, l in enumerate(['a', 'b', 'c']): print "%d: %s" % (i, l) However, I can't figure out how to combine the two: How do I use enumerate when the list in question is made of tuples?
