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Why does Python code use len() function instead of a length method?
...a protocol, they can provide alternative ways of implementing things. For example, you can create an iterable with __iter__, or with only __getitem__, and iter(x) will work either way. You can create a usable-in-bool-context object with __bool__ or __len__, and bool(x) will work either way. And so o...
Shuffling a list of objects
...
random.shuffle should work. Here's an example, where the objects are lists:
from random import shuffle
x = [[i] for i in range(10)]
shuffle(x)
# print(x) gives [[9], [2], [7], [0], [4], [5], [3], [1], [8], [6]]
# of course your results will vary
Note that sh...
Python 3 turn range to a list
... = list(range(1, 1001))
This is how you do it with generators in python2.x as well. Typically speaking, you probably don't need a list though since you can come by the value of my_list[i] more efficiently (i + 1), and if you just need to iterate over it, you can just fall back on range.
Also not...
What's the point of the X-Requested-With header?
...his can prevent CSRF attacks because this header cannot be added to the AJAX request cross domain without the consent of the server via CORS.
Only the following headers are allowed cross domain:
Accept
Accept-Language
Content-Language
Last-Event-ID
Content-Type
any others cause ...
How can I plot with 2 different y-axes?
...o scatter plots in R so that each set of points has its own (different) y-axis (i.e., in positions 2 and 4 on the figure) but the points appear superimposed on the same figure.
...
Why does “return list.sort()” return None, not the list?
... It's interesting that if an entry is added to a list, either a.append('x'), or a.extend('x) you can't chain sort() on the end either. It has to be split into 2 lines. It would have been nicer had the methods returned the list! docs.python.org/3/tutorial/datastructures.html This same message b...
Print “hello world” every X seconds
... use to schedule your task to run every n seconds.
You need a class that extends TimerTask and override the public void run() method, which will be executed everytime you pass an instance of that class to timer.schedule() method..
Here's an example, which prints Hello World every 5 seconds: -
cla...
Pycharm does not show plot
...se
plt.show()
This command tells the system to draw the plot in Pycharm.
Example:
plt.imshow(img.reshape((28, 28)))
plt.show()
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Can functions be passed as parameters?
...
Yes, consider some of these examples:
package main
import "fmt"
// convert types take an int and return a string value.
type convert func(int) string
// value implements convert, returning x as string.
func value(x int) string {
return fmt.Sprint...
Read values into a shell variable from a pipe
...ake input from the pipe, but in using the variable in the same shell that executes the read.
– chepner
Oct 2 '13 at 17:02
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