MYSQL IN OPERATOR NOT USING INDEX

After being alerted for elevated cpu on a staging mysql instance, I logged into the mysql console and ran a SHOW PROCESS LIST :

SHOW PROCESSLIST\G
*************************** 1. row ***************************
     Id: 1
   User: my_user
   Host: x.x.x.x:xxx
     db: my_db
Command: Sleep
   Time: 2
  State:
   Info: NULL
*************************** 2. row ***************************
     Id: 3
   User: my_user
   Host: x.x.x.x:xxx
     db: my_db
Command: Query
   Time: 786
  State: Sending data
   Info: SELECT file_id, fs_file_id
FROM my_data
WHERE file_id IN ('123456', 123457);

A query running for 786 seconds quickly caught my eye, my next course of action was to run an EXPLAIN :

REMOTE CONTROLLED CAR USING RASPBERRY PI AND WEBCAM

Setup

First thing I tackled was setting up the L293D H-Bridge on the Bread Board.

I found myself referencing the following Diagram a couple times.

Step one is connecting your chip down the center of your board:

From here I connected the 3 power pins to my board’s power rail using a few Jumpers :

A few more Jumpers connect each side of the chip to ground:

Finally I use a couple Wires to connect both sides of my power and ground rails:

PYTHON SAYS, SIMON'S HIPSTER BROTHER

Many of you may remember playing with a Simon Electronic Memory Game when you were younger, you know something that looks like this: At it’s core the game is rather simple, the device lights up random colors, and you need to repeat the pattern. Of course it gets harder the longer you play.

I thought it would be fun to build a Simon game using Raspberry Pi and a few electronic components:

ARDUINO VALUES TO PYTHON OVER SERIAL

I’ve done a little bit of reading on the ReadAnalogVoltage of Arduino’s home page, and they give a straight forward way to read voltage from an analog pin.

I wanted to take this one step further and send the value over serial, then read it in Python using pySerial .

My setup is very straight forward, I have a Arduino UNO , a bread board, and a battery pack holding 4x AA batteries: To start out I want to merely print the voltage value in Arduino Studio to the serial console, my code looks something like this:

PYTHON AND SENTIMENT ANALYSIS

While looking for datasets to throw at sklearn , I came across UCI Sentiment Labelled Sentences Data Set.

UCI is providing us with positive / negative tagging on real world data, the data comes from three sources ( Amazon , Yelp , and IMDB ).

The only problem is the format is a little strange.. We have a .txt file for each source, this is a raw unstructured  formatting, plus not every line is tagged with sentiment.

TEST YOUR MACHINE LEARNING

In my previous post " Python Machine Learning with Presidential Tweets “, I started messing around with sklearn and text classification.

Since then I’ve discovered a great tutorial from SciPy 2015 . This video starts out slow enough for novices, and a reoccurring theme is testing your datasets.

After watching a good chunk of this video, I decided to go back to my code and implement a testing phase. Basically I’ll split my data into two pieces, a training set , and a testing set .

PYTHON MACHINE LEARNING WITH PRESIDENTIAL TWEETS

I’ve been spending a little bit of time researching Machine Learning , and was very happy to come across a Python library called sklearn .

While digging around Google, I came across a fantastic write up on Document Classification by Zac Steward . This article went pretty deep into writing a spam filter using machine learning, and sklearn. After reading the article I wanted to try some of the concepts, but had no interest in writing a spam filter.

SENSORTAG DATA MERGED WITH OPEN WEATHER MAPS

About a week ago I worked on SensorTag metrics .

This week had some interesting weather today here in Austin, and I wanted to see to visualize it as well. Luckily Open Weather Maps offers a free API for gather near real-time weather data based on city code.

def __get_open_weather_data():

  url_path = 'http://api.openweathermap.org/data/2.5/weather'
  api_key = '??????????'
  url = '%s?zip=73301&APPID=%s'

  res = requests.get(url % (url_path, api_key))
  if res:
    if res.json().get('main'):
      return res.json()

  res = requests.get(url % (url_path, api_key))
  if res:
    if res.json().get('main'):
      return res.json()

def get_open_weather():

  data = __get_open_weather_data()

  # format our json response
  temp = round(data['main']['temp'] * 9/5 - 459.67, 2)
  pressure = round(data['main']['pressure'], 1)
  humidity = round(data['main']['humidity'], 2)
  rain = round(data['rain'].get('1h', 0.00), 2)
  clouds = data['clouds']['all']
  wind = data['wind']['speed']

  return dict(
      open_weather_temperature=temp,
      open_weather_pressure=pressure,
      open_weather_humidity=humidity,
      open_weather_rain=rain,
      open_weather_clouds=clouds,
      open_weather_wind=wind
  )

Then I merge with my SensorTag data, appending these new keys to my json file:

ARDUINO MEET RASPBERRY PI

While at the electronics store the other day, I noticed they had motion detectors on sale for only $4. I decided with my latest obsession of electronic tinkering, picking up a OSEEP Passive Infrared Sensor (PIR) Module might be fun.

I guess I should have done a little more reading on the packaging; by the time I was home, I noticed this sensor reported in analog , not digital. This was an issue as the Raspberry Pi only reads digital input.

RASPBERRY PI AND OFFICIAL NFL SCORE BOARD API

Now that I’ve got my hands on a Raspberry Pi 3 Model B Motherboard , I decided nows a good time to play around with the 16x2 LCD Module Controller HD44780 I had laying around (I’ve had this thing since December 2015).

A live NFL (National Football League) score board seemed fitting as the season just started.

I found a really good write up on raspberrypi-spy.co.uk about wiring up the controller and Pi, here is the diagram I used: