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Calculating arithmetic mean (one type of average) in Python
...
Why have you called max?
– 1 -_-
Jul 25 '17 at 6:41
3
See the question abo...
How to access object attribute given string corresponding to name of that attribute
...ay prefer to use a generalized getter method like so:
class Test:
def __init__(self):
self.attr1 = 1
self.attr2 = 2
def get(self,varname):
return getattr(self,varname)
t = Test()
x = "attr1"
print ("Attribute value of {0} is {1}".format(x, t.get(x)))
Outputs:
At...
WakeLock 扩展：保持设备唤醒扩展，防止系统休眠和电池优化 · App Inventor 2 中文网
...hen 计时器1.Timer() {
UrsAI2WakeLock1.AquirePartialWakeLock()
标签_状态.Text = "正在记录数据"
UrsAI2WakeLock1.Release()
}
2. MQTT 客户端
保持 MQTT 连接活跃：
when Screen1.Initialize() {
UrsAI2WakeLock1.AquireWifiLock()
UrsAI2WakeLock1.Aquir...
how to emulate “insert ignore” and “on duplicate key update” (sql merge) with postgresql?
...use a query like this: "start transaction; create temporary table temporary_table as select * from test where false; copy temporary_table from 'data_file.csv'; lock table test; update test set data=temporary_table.data from temporary_table where test.id=temporary_table.id; insert into test select * ...
How to crop an image in OpenCV using Python
...y simple. Use numpy slicing.
import cv2
img = cv2.imread("lenna.png")
crop_img = img[y:y+h, x:x+w]
cv2.imshow("cropped", crop_img)
cv2.waitKey(0)
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...
How does Apple know you are using private API?
...ist all linked symbols. This can detect
Undocumented C functions such as _UIImageWithName;
Objective-C classes such as UIProgressHUD
Ivars such as UITouch._phase (which could be the cause of rejection of Three20-based apps last few months.)
3. Listing Objective-C selectors, or strings
Objective...
Avoid browser popup blockers
...create a blank popup on user action
var importantStuff = window.open('', '_blank');
Optional: add some "waiting" info message. Examples:
a) An external HTML page: replace the above line with
var importantStuff = window.open('http://example.com/waiting.html', '_blank');
b) Text: add the follow...
Open a URL in a new tab (and not a new window)
... is a trick,
function openInNewTab(url) {
var win = window.open(url, '_blank');
win.focus();
}
In most cases, this should happen directly in the onclick handler for the link to prevent pop-up blockers, and the default "new window" behavior. You could do it this way, or by adding an event li...
Handling an empty UITableView. Print a friendly message
...xtension:
import UIKit
extension UITableView {
func setEmptyMessage(_ message: String) {
let messageLabel = UILabel(frame: CGRect(x: 0, y: 0, width: self.bounds.size.width, height: self.bounds.size.height))
messageLabel.text = message
messageLabel.textColor = .black
...
手电筒使用指导 · App Inventor 2 中文网
...确状态：
when Screen1.Initialize() {
更新按钮()
}
when 按钮_开关.Click() {
手电筒1.Toggle()
更新按钮()
}
procedure 更新按钮() {
if 手电筒1.IsOn() {
按钮_开关.Text = "关闭手电筒"
按钮_开关.BackgroundColor = &HFFFFC107
} else {
按钮_开...