Fix Python – Is there a way in Pandas to use previous row value in dataframe.apply when previous value is also calculated in the apply?

I have the following dataframe:
Index_Date A B C D
================================
2015-01-31 10 10 Nan 10
2015-02-01 2 3 Nan 22
2015-02-02 10 60 Nan 280
2015-02-03 10 100 Nan 250

Require:
Index_Date A B C D
================================
2015-01-31 10 10 10 10
2015-02-01 ….

Fix Python – How can I make sense of the `else` clause of Python loops?

Many Python programmers are probably unaware that the syntax of while loops and for loops includes an optional else: clause:
for val in iterable:
do_something(val)
else:
clean_up()

The body of the else clause is a good place for certain kinds of clean-up actions, and is executed on normal termination of the loop: I.e., exiting the loop wi….

Fix Python – What is the pythonic way to detect the last element in a ‘for’ loop?

I’d like to know the best way (more compact and “pythonic” way) to do a special treatment for the last element in a for loop. There is a piece of code that should be called only between elements, being suppressed in the last one.
Here is how I currently do it:
for i, data in enumerate(data_list):
code_that_is_done_for_every_element
if i !=….

Fix Python – How to check if all elements of a list match a condition?

I have a list consisting of like 20000 lists. I use each list’s 3rd element as a flag. I want to do some operations on this list as long as at least one element’s flag is 0, it’s like:
my_list = [[“a”, “b”, 0], [“c”, “d”, 0], [“e”, “f”, 0], …..]

In the beginning, all flags are 0. I use a while loop to check if at least one element’s flag is 0:
….