python-2.7

问题 I would like to know is there a method that can read multiple lines from a file batch by batch. For example: with open(filename, 'rb') as f: for n_lines in f: process(n_lines) In this function, what I would like to do is: for every iteration, next n lines will be read from the file, batch by batch. Because one single file is too big. What I want to do is to read it part by part. 回答1: itertools.islice and two arg iter can be used to accomplish this, but it's a little funny: from itertools

问题 I would like to know is there a method that can read multiple lines from a file batch by batch. For example: with open(filename, 'rb') as f: for n_lines in f: process(n_lines) In this function, what I would like to do is: for every iteration, next n lines will be read from the file, batch by batch. Because one single file is too big. What I want to do is to read it part by part. 回答1: itertools.islice and two arg iter can be used to accomplish this, but it's a little funny: from itertools

问题 I am learning basic GUI in Python, and I came across a sample example to read file name from file explorer on Stack Overflow. from Tkinter import Tk from tkFileDialog import askopenfilename Tk().withdraw() # we don't want a full GUI, so keep the root window from appearing filename = askopenfilename() # show an "Open" dialog box and return the path to the selected file print(filename) This particular script is working fine when I am trying to run it in IDLE, but the same is not running if I am

问题 This question already has answers here : Converting datetime.date to UTC timestamp in Python (10 answers) Closed 4 years ago . What is a classy way to store date and time information in a float in python with millisecond precision? Edit: I'm using python 2.7 I've hacked together the following: DT = datetime.datetime(2016,01,30,15,16,19,234000) #trailing zeros are required DN = (DT - datetime.datetime(2000,1,1)).total_seconds() print repr(DN) Output: 507482179.234 And then to revert back to

问题 Is there a simple/one-line python equivalent to R's gsub function? strings = c("Important text, !Comment that could be removed", "Other String") gsub("(,[ ]*!.*)$", "", strings) # [1] "Important text" "Other String" 回答1: For a string: import re string = "Important text, !Comment that could be removed" re.sub("(,[ ]*!.*)$", "", string) Since you updated your question to be a list of strings, you can use a list comprehension. import re strings = ["Important text, !Comment that could be removed"

问题 Is there a simple/one-line python equivalent to R's gsub function? strings = c("Important text, !Comment that could be removed", "Other String") gsub("(,[ ]*!.*)$", "", strings) # [1] "Important text" "Other String" 回答1: For a string: import re string = "Important text, !Comment that could be removed" re.sub("(,[ ]*!.*)$", "", string) Since you updated your question to be a list of strings, you can use a list comprehension. import re strings = ["Important text, !Comment that could be removed"

问题 Is there a simple/one-line python equivalent to R's gsub function? strings = c("Important text, !Comment that could be removed", "Other String") gsub("(,[ ]*!.*)$", "", strings) # [1] "Important text" "Other String" 回答1: For a string: import re string = "Important text, !Comment that could be removed" re.sub("(,[ ]*!.*)$", "", string) Since you updated your question to be a list of strings, you can use a list comprehension. import re strings = ["Important text, !Comment that could be removed"

问题 I am having difficulty figuring out what the syntax would be for the last key in a Python dictionary. I know that for a Python list, one may say this to denote the last: list[-1] I also know that one can get a list of the keys of a dictionary as follows: dict.keys() However, when I attempt to use the logical following code, it doesnt work: dict.keys(-1) It says that keys cant take any arguments and 1 is given. If keys cant take args, then how can I denote that I want the last key in the list?

问题 I've got the authentication working with flask-login, but it seems like no matter what I use for the cookie duration in flask, the session is still authenticated. Am I setting the config variables properly for flask-login? I've tried app.REMEMBER_COOKIE_DURATION = datetime.timedelta(seconds=30) app.config["REMEMBER_COOKIE_DURATION"] = datetime.timedelta(seconds=30) Even if I close the browser, wait a while, and hit a url that should be protected, I can still access it. Is this related to this

问题 I've got the authentication working with flask-login, but it seems like no matter what I use for the cookie duration in flask, the session is still authenticated. Am I setting the config variables properly for flask-login? I've tried app.REMEMBER_COOKIE_DURATION = datetime.timedelta(seconds=30) app.config["REMEMBER_COOKIE_DURATION"] = datetime.timedelta(seconds=30) Even if I close the browser, wait a while, and hit a url that should be protected, I can still access it. Is this related to this