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Introducing Lake Pend Oreille

From: Code Clinic: PHP

Video: Introducing Lake Pend Oreille

Hello, and welcome to Code Clinic. This month, we'll work on a problem in You'll find several weather summaries, a web cam, and the raw data The first column, is the day the wind gust was recorded.

Introducing Lake Pend Oreille

Hello, and welcome to Code Clinic. My name is David Powers. Code Clinic is a monthly course where unique a problem is introduced to a collection of lynda.com authors. In response, each author creates a solution, using the programming language of their choice. In my case, I'll be using PHP. You can learn several things from Code Clinic. Different approaches to solving the problem, the pros and cons of different languages, and some tips and tricks to incorporate into your own coding practices.

This month, we'll work on a problem in statistical analysis and to some extent, handling big data. It's common to use a computer to manipulate and summarize large amounts of information, providing important insights into how to improve or handle a situation. In this problem, we'll use weather data collected by the US Navy from Lake Pend Oreille in northern Idaho. Lake Pend Oreille is the fifth deepest fresh water lake in the United States. So deep in fact, that the US Navy uses it to test submarines.

As part of that testing, the US Navy compiles an exhaustive list of weather statistics, including wind speed, air temperature and barometric pressure. You can browse this data by pointing your browser at http://lpo.dt.navy.mil. You'll find several weather summaries, a web cam, and the raw data they collect every five or six minutes archived as standard text files.

For anyone living or working on Lake Pend Oreille, weather statistics are an important part of every day life. Especially, if your on a small boat in the middle of the lake. There can be a significant difference between average wind speed and median wind speed.In this challenge I'll be using PHP to calculate the mean and median of the wind speed, air temperature and barometric pressure recorded into the deep more station for a given range of dates. The other authors will each use their own favorite language to solve the same problem.

First, let's briefly review mean and median. These are both statistics, to explain how they're calculated, we need a set of numbers. How about 14 readings for Wind Gusts at deep more weather station on January 1, 2014. You can see the data of this website. The first column, is the day the wind gust was recorded. The second column, is the time it was recorded. And the third column, is the wind gust in miles per hour. The mean, is also known as the average.

So calculate the mean of a range of numbers, simply add the values in the set and then divide by the number of values. In this example, we add all of these numbers together and then divide the sum by 14 the amount of numbers in the set. In this case, the mean is equal to nine. The median is the middle value in a set of data sorted in ascending order. Think of the median as the median strip of the road, it always marks the center.

To calculate the median first, sort the numbers from lowest to highest. If there's an odd number of values, then just take the middle number. If there's an even number of values, then calculate the average of the central two numbers. In this case, there's an even number of values. So we sort, then take the average of the middle two values, eight and eleven, so the median is 9.5. In addition, some offices including myself have chosen to implement a web service to provide access to the new weather statistics created by the author's program.

This is typically done by creating a RESTful API, which when called, returns information in a format known as JSON. For a detailed description of JSON and it's uses please, refer to JavaScript and JSON by Ray Villalobos. If you make this http call to my website of foundationphp.com, you would expect to receive the mean and median for wind speed, air temperature, and barometric pressure for the range of dates starting from March 19, 2011, and running until midnight of the following day.

The JSON data returned looks like this. So that is our first challenge. Pull statistics from a data set available online. Perhaps, you want to pause and create a solution of your own. How would you solve the problem? In the next videos, I'll show you how I solve the challenge

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Code Clinic: PHP

47 video lessons · 3981 viewers

David Powers

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  1. 8m 49s
    1. Welcome
      1m 18s
    2. What you should know before watching this course
      4m 40s
    3. Using the exercise files
      1m 56s
    4. Getting the most from Code Clinic
  2. 1h 34m
    1. Introducing Lake Pend Oreille
      5m 4s
    2. Overview of my solution
      3m 22s
    3. Setting up the database
      4m 55s
    4. Retrieving the full-year records
      5m 20s
    5. Processing the full-year records
      10m 49s
    6. Priming the date_recorded column
      7m 47s
    7. Inserting the full-year data into the database
      6m 48s
    8. Processing individual days
      6m 54s
    9. Retrieving a year's data a day at a time
      7m 41s
    10. Keeping the data up to date
      4m 27s
    11. Calculating the mean and median values
      7m 21s
    12. Creating a web service
      6m 21s
    13. Getting the required data
      6m 50s
    14. Building the web service response
      10m 38s
  3. 49m 47s
    1. Identify the image subset
      3m 14s
    2. Overview of my solution
      3m 19s
    3. Setting up the files
      2m 43s
    4. Calculating the scaling ratio
      6m 28s
    5. Using a custom class to scale images
      6m 25s
    6. Generating the thumbnails
      7m 49s
    7. Using subimage-search in ImageMagick
      4m 32s
    8. Analyzing the image statistics
      4m 45s
    9. Finding the cropped images
      7m 13s
    10. Running the script and displaying the results
      3m 19s
  4. 39m 3s
    1. A classic CS interview question
      2m 4s
    2. Overview of my solution
      3m 48s
    3. Finding all possible combinations
      6m 26s
    4. Detecting horizontal attacks programmatically
      4m 8s
    5. Implementing the checkLayout() function
      6m 25s
    6. Rotating the chessboard
      4m 59s
    7. Eliminating duplicate solutions
      6m 34s
    8. Displaying the unique solutions
      4m 39s
  5. 21m 33s
    1. Build a musical instrument using mouse movements
      1m 35s
    2. Overview of my solution
      2m 1s
    3. Using the Web Audio API
      2m 47s
    4. Creating the tone generator
      7m 39s
    5. Controlling the frequency and volume
      7m 31s
  6. 31m 29s
    1. Searching directories for photos NEW
      2m 44s
    2. Overview of my solution NEW
      3m 24s
    3. Finding the images NEW
      5m 30s
    4. Extracting Exif and IPTC metadata NEW
      6m 18s
    5. Extracting XMP metadata NEW
      6m 22s
    6. Reorganizing the folder structure NEW
      7m 11s

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