Missing xcrun on macOS High Sierra

Error

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

error: "" unsupported

Solution:

• Re-install XCode from App Store (~20 minutes)
• Open XCode and agree to lice agreement
• Allow it to "Instal components..."

This resolved my problem, but optionally you can try the following:

• xcode-select --install
• sudo xcodebuild -license
• xcode-select --reset

Missing xcrun on macOS High Sierra

Error

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

error: "" unsupported

Solution:

• Re-install XCode from App Store (~20 minutes)
• Open XCode and agree to lice agreement
• Allow it to "Instal components..."

This resolved my problem, but optionally you can try the following:

• xcode-select --install
• sudo xcodebuild -license
• xcode-select --reset

What is Neural Network (NN)? by 3Blue1Brown

The video discusses:

• handwritten digit recognition example
• kernel size 28x28 pixel = 784 array
• activation layer 784 (1-dimensional) array 
• 2 hidden layers, each with 16 neurons (arbitrary choice)
• hidden layers correspond to macro and micro features within the digit
• 
  
  
  
  
• output layer 0..9, the largest value is the most likely selection of the NN
• He notes that the same principle can be applied to speech recognition.
• neuron parameters: knobs to adjust
• weights: connections between neurons
• activation function: normalizes the values between 0..1

https://www.youtube.com/watch?v=aircAruvnKk&list=PLZHQObOWTQDNU6R1_67000Dx_ZCJB-3pi&index=3

sed command line tool

The sed command line tool allows you to pipe a string of text and substitute part of it.

Note that it does for the first occurrence only:

$ echo "my, this is my sentence" | sed 's/my/My/'
My, this is my sentence

Escaping forward slashes with the backslashes:

$ echo "convert /usr/local/bin to /common/bin" | sed "s/\/usr\/local\/bin/\/common\/bin/"
convert /common/bin to /common/bin

$ echo "Repeat me 5 times." | sed 's/[0-9]/& & & & &/'

Repeat me 5 5 5 5 5 times.

sed command line tool

The sed command line tool allows you to pipe a string of text and substitute part of it.

Note that it does for the first occurrence only:

$ echo "my, this is my sentence" | sed 's/my/My/'
My, this is my sentence

Escaping forward slashes with the backslashes:

$ echo "convert /usr/local/bin to /common/bin" | sed "s/\/usr\/local\/bin/\/common\/bin/"
convert /common/bin to /common/bin

$ echo "Repeat me 5 times." | sed 's/[0-9]/& & & & &/'

Repeat me 5 5 5 5 5 times.