Search results
In a for loop and by using tuple unpacking (see the example: i, row), I use the row for only viewing the value and use i with the loc method when I want to modify values. As stated in previous answers, here you should not modify something you are iterating over.
@TheRealChx101: It's lower than the overhead of looping over a range and indexing each time, and lower than manually tracking and updating the index separately.
Jul 21, 2010 · When you iterate through dictionaries using the for .. in .. -syntax, it always iterates over the keys (the values are accessible using dictionary[key]). To iterate over key-value pairs, use the following: for k,v in dict.iteritems() in Python 2. for k,v in dict.items() in Python 3.
Use break and continue to do this. Breaking nested loops can be done in Python using the following: for a in range(...): for b in range(..): if some condition: # break the inner loop break else: # will be called if the previous loop did not end with a `break` continue # but here we end up right after breaking the inner loop, so we can # simply break the outer loop as well break
Aug 31, 2009 · Take a set of data. Make a FOR Parameter %%G equal to some part of that data. Perform a command (optionally using the parameter as part of the command). --> Repeat for each item of data. If you are using the FOR command at the command line rather than in a batch program, use just one percent sign: %G instead of %%G.
Jun 10, 2010 · The condition: checks a condition every time before the loop block is executed, and quits the loop if false; The afterthought: performed every time after the loop block is executed; These three components are separated from each other by a ; symbol.
Oct 3, 2012 · The range based for loop syntax is nice and concise. However, debugging may call for the explicit knowledge of the index. For example: a file is written by the loop. It is found that line 125 corresponding to the 125th iteration produces incorrect values. How do you breakpoint the loop at the 125th iteration for debug?
votes. The way for loop is processed is as follows. 1 First, initialization is performed (i=0) 2 the check is performed (i < n) 3 the code in the loop is executed. 4 the value is incremented. 5 Repeat steps 2 - 4. This is the reason why, there is no difference between i++ and ++i in the for loop which has been used.
The range function wil give you a list of numbers, while the for loop will iterate through the list and execute the given code for each of its items. for i in range(5): print i. This simply executes print i five times, for i ranging from 0 to 4. for i in range(5): a=i+1. This will execute a=i+1 five times.
Aug 9, 2008 · The problems are somewhat restricted because the possible jump targets are restricted (beginning of loop, or past the loop only) -- but they are there, in particular if you scatter multiple instances through the loop: bad readability/loss of structure/surprising control flows and problems with resource management (the "goto" potentially skips cleanup code in the loop, similar to scattered ...
