python-2.7

问题 Code: class Fraction(object): def __init__(self, num, denom): self.numerator = num self.denominator = denom def main(): f = Fraction(1, 3) print type(f) if __name__ == "__main__": main() Output: <class '__main__.Fraction'> Question: Why is the type __main__.Fraction instead of just Fraction ? Why is there "." between __main__ and Fraction ? "." implies that Fraction is a sub-class of __main__ . But why? Even if I remove If __name__ == "__main__" from the code, I still get the same output:

问题 I was trying to understand how reduce works through this website. The example they have mentioned is quite good and easy to understand. http://book.pythontips.com/en/latest/map_filter.html#reduce a = reduce((lambda x, y: x * y), [1, 2, 3, 4]) The above function will multiple each and every number in list and assign to a . However, I got totally stumped when I came across following function in project. def compose(*fns): return reduce(lambda acc, fn: lambda *args: acc(fn(*args)), fns, lambda _

问题 I have two files which contains same number of lines. "file1.txt" contains following lines: Attitude is a little thing that makes a big difference The only disability in life is a bad attitude Abundance is, in large part, an attitude Smile when it hurts most "file2.txt" contains: Attitude is a little thing that makes a big difference Everyone has his burden. What counts is how you carry it Abundance is, in large part, an attitude A positive attitude may not solve all your problems I want to

问题 I have two files which contains same number of lines. "file1.txt" contains following lines: Attitude is a little thing that makes a big difference The only disability in life is a bad attitude Abundance is, in large part, an attitude Smile when it hurts most "file2.txt" contains: Attitude is a little thing that makes a big difference Everyone has his burden. What counts is how you carry it Abundance is, in large part, an attitude A positive attitude may not solve all your problems I want to

问题 For example: 'hello'.count('e') Is this O(n)? I'm guessing the way it works is it scans 'hello' and increments a counter each time the letter 'e' is seen. How can I know this without guessing? I tried reading the source code here, but got stuck upon finding this: def count(s, *args): """count(s, sub[, start[,end]]) -> int Return the number of occurrences of substring sub in string s[start:end]. Optional arguments start and end are interpreted as in slice notation. """ return s.count(*args)

问题 For example: 'hello'.count('e') Is this O(n)? I'm guessing the way it works is it scans 'hello' and increments a counter each time the letter 'e' is seen. How can I know this without guessing? I tried reading the source code here, but got stuck upon finding this: def count(s, *args): """count(s, sub[, start[,end]]) -> int Return the number of occurrences of substring sub in string s[start:end]. Optional arguments start and end are interpreted as in slice notation. """ return s.count(*args)

问题 For example: 'hello'.count('e') Is this O(n)? I'm guessing the way it works is it scans 'hello' and increments a counter each time the letter 'e' is seen. How can I know this without guessing? I tried reading the source code here, but got stuck upon finding this: def count(s, *args): """count(s, sub[, start[,end]]) -> int Return the number of occurrences of substring sub in string s[start:end]. Optional arguments start and end are interpreted as in slice notation. """ return s.count(*args)

问题 I'm developing a backup daemon that will run silently in the background. The daemon relies on the duplicity backup software, which when backing up requires an encryption key. I cannot ask for the password through the console because obviously, the daemon has no access to such. How could I easily create a prompt that asks the user to type in a password, and returns it to the application (through a Python variable)? I'm using Python 2.7 . 回答1: from Tkinter import * def getpwd(): password = ''

问题 I have a table in my AWS Glue Data Catalog called 'mytable'. This table is in an on-premises Oracle database connection 'mydb'. I'd like to filter the resulting DynamicFrame to only rows where the X_DATETIME_INSERT column (which is a timestamp) is greater than a certain time (in this case, '2018-05-07 04:00:00'). Afterwards, I'm trying to count the rows to ensure that the count is low (the table is about 40,000 rows, but only a few rows should meet the filter criteria). Here is my current

问题 I have a table in my AWS Glue Data Catalog called 'mytable'. This table is in an on-premises Oracle database connection 'mydb'. I'd like to filter the resulting DynamicFrame to only rows where the X_DATETIME_INSERT column (which is a timestamp) is greater than a certain time (in this case, '2018-05-07 04:00:00'). Afterwards, I'm trying to count the rows to ensure that the count is low (the table is about 40,000 rows, but only a few rows should meet the filter criteria). Here is my current