Using Python server to run d3js code from local Windows directory

Some of the d3js code samples may produce errors in certain browsers when you try to run static files locally.
You can run python’s simplehttpserver while browsing the samples.

  1. Open up a new Command Prompt window:
    1. WinKey+R
    2. Input “cmd“.
    3. Enter
  2. Via the command line, navigate into the directory that you want served. For example, if your project folder is in your c:tmp folder, you could type:
    cd c:tmp
  3. To start the HTTP server type:
    python -m SimpleHTTPServer 8888 &
  4. To stop the HTTP server from the Command Prompt use the keyboard command Ctrl+C (⌃+C)
  5. Switch back to your web browser and visit the following URL: http://localhost:8888/

Android Studio Tips and Tricks

Editor Actions

If you’re unfamiliar with using Android Studio and the IntelliJ IDEA interface, this page provides some tips to help you get started with some of the most common tasks and productivity enhancements.

[table id=1 /]

It is always useful to visit Android Studio -> Preferences -> Keymap for the full list of shortcuts


Tick Android Studio -> Preferences -> Editor -> General -> Appearance -> Show line number 


Modify the Shell Path in OSX to Access adb Through Terminal

The shell path for a user in OSX is a set of locations in the filing system whereby the user can use certain applications, commands and programs without the need to specify the full path to that command or program in the Terminal. This will work in all OSX operating systems.

You can find out whats in your path by launching Terminal in Applications/Utilities and entering:

echo $PATH

Adding in a Permanent Location

To make the new path stick permanently you need to create a .bash_profile file in your home directory and set the path there. This file control various Terminal environment preferences including the path.

nano  ~/.bash_profile

Create the .bash_profile file with a command line editor called nano

export PATH="/Users/ofir/Library/Android/sdk/platform-tools:$PATH"

Add in the above line which declares the new location /Users/ofir/Library/Android/sdk/platform-tools as well as the original path declared as $PATH.

So now when the Terminal is relaunched or a new window made and you check the the path by

echo $PATH

You will get the new path at the front followed by the default path locations, all the time



Bluetooth Debugging on Android Wear

I’ve just bought a new ASUS ZenWatch and I’m working on a small application to extract the sensors data from the watch.

This post ( ) is describing the basic steps required to setup a device for debugging and to setup a debugging session. I’ve listed below some additional steps to help with the troubleshooting if things doesn’t work as planned.

Android Debug Bridge (adb)

Android Debug Bridge (adb) is a versatile command line tool that lets you communicate with an emulator instance or connected Android-powered device. It is a client-server program that includes three components:

  • A client, which runs on your development machine. You can invoke a client from a shell by issuing an adb command. Other Android tools such as DDMS also create adb clients.
  • A server, which runs as a background process on your development machine. The server manages communication between the client and the adb daemon running on an emulator or device.
  • A daemon, which runs as a background process on each emulator or device instance.

Setup Devices for Debugging

  1. Enable USB debugging on the handheld:
    • Open the Settings app and scroll to the bottom.
    • If it doesn’t have a Developer Options setting, tap About Phone (or About Tablet), scroll to the bottom, and tap the build number 7 times.
    • Go back and tap Developer Options.
    • Enable USB debugging.
  2. Enable Bluetooth debugging on the wearable:
    1. Tap the home screen twice to bring up the Wear menu.
    2. Scroll to the bottom and tap Settings.
    3. Scroll to the bottom. If there’s no Developer Options item, tap About, and then tap the build number 7 times.
    4. Tap the Developer Options item.
    5. Enable Debug over Bluetooth.

Set Up a Debugging Session

  • On the handheld, open the Android Wear companion app.
  • Tap the menu on the top right and select Settings.
  • Enable Debugging over Bluetooth. You should see a tiny status summary appear under the option:
Host: disconnected
Target: connected
  • Connect the handheld to your machine over USB.
  • In the Android Studio open the Terminal (Alt+F12 Windows) and run:
    adb forward tcp:4444 localabstract:/adb-hub
    adb connect localhost:4444

    Note: You can use any available port that you have access to.

    • adb forward forwards socket connections from a specified local port to a specified remote port on the emulator/device instance. Map a socket through the phone that is paired to your Wear device.
    • adb connect will connect to the device
  • A message will appear on the phone to allow Wear Debugging, press OK


  • In the Android Wear companion app, you should see the status change to:
Host: connected
Target: connected

Well, this is the happy flow.

While debugging I’ve encountered some issues, especially after disconnecting the phone from the USB cable.

First, print a list of all attached emulator/device instances:

adb devices
List of devices attached
LGD855bxxxxx  device

In this case you can see only the phone and not the watch, so you will need to execute

adb forward tcp:4444 localabstract:/adb-hub
adb connect localhost:4444

In other cases you may get the error message

error: more than one device/emulator

You may need to terminates the adb server process:

adb kill-server

Now you can execute the adb forward and adb connect commands

adb forward tcp:4444 localabstract:/adb-hub
adb connect localhost:4444

If you get an error message

error: device unauthorized.

Try revoking the permissions on the device – Developer options -> Revoke USB debugging authorizations. Then plug the device in and accept it again.


[FIXED] No Symbols For Paired Apple Watch iOS 9 / watchOS 2 / Xcode 7 [Beta 5]

I’m trying to get my watchOS 2 app running on my Apple Watch.

With Beta 4, I was able to run the WatchKit App (including HealthKit) and debug it on the Watch.

When upgrading to Beta 5, I couldn’t select the “iPhone + Apple watch” combination, as it was marked as Ineligible in the Active Scheme, with the following message  “xxx iPhone + yyy Apple Watch (no symbols for paired apple watch)”.

After many hours of trials and mainly errors, the solution that eventually worked for me is based on this post, but to simplify things I’ve followed the initial steps, changed the directory name to work with Beta 5 and zipped the relevant folders. So the simplified version for Beta 5 is:

  1. Download the zip file from here to the target directory:
  2. Unzip the file. You should see a new folder named “WatchOS DeviceSupport” under your Xcode folder, with another folder named “2.0 (13S5325c)”.


  1. Open project on Xcode 7 beta.
  2. Disconnect and connect your iPhone.

That’s all – it worked for me, I hope it will work for you as well.

Summing multiple columns of a Data Frame and merging with the first unique row [R Tips & Tricks]

Taking the mtcars dataset as an example, I need to split the data frame by “cyl” and sum by multiple columns, “wt” and “drat”.

Next, I will need to merge the “wt” and “drat” sums to the first unique record by “cyl”.

Let’s start with the raw data, the mtcars data frame:

##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
## Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

Summing over multiple columns by using the ddply function:

df2 <- ddply(mtcars, c("cyl"), function(x) colSums(x[c("wt", "drat")]))
##   cyl     wt  drat
## 1   4 25.143 44.78
## 2   6 21.820 25.10
## 3   8 55.989 45.21

Using duplicated is quick way to find the first unique instance by “cyl”:

df3 <- mtcars[!duplicated(mtcars$cyl),]
##                    mpg cyl disp  hp drat   wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.62 16.46  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.32 18.61  1  1    4    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.44 17.02  0  0    3    2

Before merging the two data frames (df2 and df3), we remove “wt” and “draft” from df3, to be replaced later by the columns’ sum from df2:

drops <- c("wt","drat")
df3.dropped <- df3[,!(names(df3) %in% drops)]
##                    mpg cyl disp  hp  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 16.46  0  1    4    4
## Datsun 710        22.8   4  108  93 18.61  1  1    4    1
## Hornet Sportabout 18.7   8  360 175 17.02  0  0    3    2

We will now merge the two data frames to produce the final data frame:

merged.left <- merge(x = df2, y = df3.dropped, by = "cyl", all.x=TRUE)
##   cyl     wt  drat  mpg disp  hp  qsec vs am gear carb
## 1   4 25.143 44.78 22.8  108  93 18.61  1  1    4    1
## 2   6 21.820 25.10 21.0  160 110 16.46  0  1    4    4
## 3   8 55.989 45.21 18.7  360 175 17.02  0  0    3    2

Extracting ID from multiple strings formats using strsplit [R Tips & Tricks]

I needed to extract an ID across multiple formats and different datasets, where the possible patterns are:

ID-xx-yy, ID-xx, ID

For example:

00018523-01-02, 078-11, 789522314H

strsplit did the work:

## [1] "00018523"
## [1] "078"
## [1] "789522314H"