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Python Linked List
...bda lst, el: cons(el, lst), reversed(args), None)
car = lambda lst: lst[0] if lst else lst
cdr = lambda lst: lst[1] if lst else lst
nth = lambda n, lst: nth(n-1, cdr(lst)) if n > 0 else car(lst)
length = lambda lst, count=0: length(cdr(lst), count+1) if lst else count
begin = lambda *args: arg...
Using $_POST to get select option value from HTML
... Why is it always better to give values to your <option> tags? "If no value attribute is included, the value defaults to the text contained inside the element". If it works, what's wrong with that?
– osullic
Jan 8 '19 at 15:46
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Dynamically load a JavaScript file
...rary.js", type: "text/javascript"});
The problem here is that we do not know when the external script file is fully loaded.
We often want our dependant code on the very next line and like to write something like:
if (iNeedSomeMore) {
Script.load("myBigCodeLibrary.js"); // includes code for ...
How do I create a constant in Python?
...t declare a variable or value as constant in Python. Just don't change it.
If you are in a class, the equivalent would be:
class Foo(object):
CONST_NAME = "Name"
if not, it is just
CONST_NAME = "Name"
But you might want to have a look at the code snippet Constants in Python by Alex Martelli.
...
Pandas aggregate count distinct
...
This answer is outdated. You can now use nunique directly. See @Blodwyn Pig's solution below
– Ted Petrou
Nov 5 '17 at 20:07
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How to pass a user defined argument in scrapy spider
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The above code is only partially working for me. For eg. If I define domain using self.domain, I'm still not able to access it outside the __init__ method. Python throws a not defined error. BTW, why have you omitted the super call? PS. I'm working with the CrawlSpider class
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Does MongoDB's $in clause guarantee order
...course will be the natural order or by the selected index order as shown.
If you need to preserve this order, then you basically have two options.
So let's say that you were matching on the values of _id in your documents with an array that is going to be passed in to the $in as [ 4, 2, 8 ].
Appr...
How to make a JSONP request from Javascript without JQuery?
...ion which logs all items in someone's home. My application is set up and I now want to retrieve all the items in the main bedroom.
My application is on app.home.com. The apis I need to load data from are on api.home.com.
Unless the server is explicitly set up to allow it, I cannot use ajax to load t...
Adding a directory to $LOAD_PATH (Ruby)
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I would say go with $:.unshift File.dirname(__FILE__) over the other one, simply because I've seen much more usage of it in code than the $LOAD_PATH one, and it's shorter too!
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Lua简明教程 - 脚本技术 - 清泛IT论坛，有思想、有深度
...m
num = num + 1
end
print("sum =",sum)复制代码
if-else分支
if age == 40 and sex =="Male" then
print("男人四十一枝花")
elseif age > 60 and sex ~="Female" then
print("old man without country!")
...