Book Image

Python for Secret Agents - Volume II - Second Edition

By : Steven F. Lott
Book Image

Python for Secret Agents - Volume II - Second Edition

By: Steven F. Lott

Overview of this book

Python is easy to learn and extensible programming language that allows any manner of secret agent to work with a variety of data. Agents from beginners to seasoned veterans will benefit from Python's simplicity and sophistication. The standard library provides numerous packages that move beyond simple beginner missions. The Python ecosystem of related packages and libraries supports deep information processing. This book will guide you through the process of upgrading your Python-based toolset for intelligence gathering, analysis, and communication. You'll explore the ways Python is used to analyze web logs to discover the trails of activities that can be found in web and database servers. We'll also look at how we can use Python to discover details of the social network by looking at the data available from social networking websites. Finally, you'll see how to extract history from PDF files, which opens up new sources of data, and you’ll learn about the ways you can gather data using an Arduino-based sensor device.
Table of Contents (7 chapters)
6
Index

Seeing a better blinking light


The core blinking light sketch uses a delay(1000) to essentially stop all work for 1 second. If we want to have a more responsive gadget, this kind of delay can be a problem. This design pattern is called Busy Waiting or Spinning: we can do better.

The core loop() function is executed repeatedly. We can use the millis() function to see how long it's been since we turned the LED on or turned the LED off. By checking the clock, we can interleave LED blinking with other operations. We can gather sensor data as well as check for button presses, for example.

Here's a way to blink an LED that allows for additional work to be done:

const int LED=13; // the on-board LED
void setup() {
    pinMode( LED, OUTPUT );
}
void loop() {
    // Other Work goes here.
    heartbeat();
}
// Blinks LED 13 once per second.
void heartbeat() {
  static unsigned long last= 0;
  unsigned long now= millis();
  if (now - last > 1000) {
    digitalWrite( LED, LOW );
    last= now;
  }
...