commit
d35875913a
@ -0,0 +1,89 @@
|
||||
# Creative coding and software languages
|
||||
|
||||
**Programming**:
|
||||
|
||||
- Processing information is old
|
||||
- Relevant to many disciplines
|
||||
|
||||
---
|
||||
|
||||
**Tools used to develop code-based artworks**:
|
||||
|
||||
- Programming languages
|
||||
- Text editors
|
||||
- IDE
|
||||
- Compilers / interpreters
|
||||
- Libraries
|
||||
- Hardware
|
||||
|
||||
---
|
||||
|
||||
Code must be **understandable** and **readable** for humans.
|
||||
<br>
|
||||
_Programming is an art._
|
||||
|
||||
# Creative coding
|
||||
|
||||
_A process based on exploration, iteration, reflection and discovery, where code is used as the primary medium to create a wide range of media artifacts._
|
||||
|
||||
---
|
||||
|
||||
### The AI era:
|
||||
|
||||
**AI as a tool:**
|
||||
|
||||
- Programming understanding is required
|
||||
- _Natural language prompts_ are creative tools
|
||||
|
||||
**Fundamental elements of generative art**
|
||||
|
||||
- Repetition
|
||||
- Randomness
|
||||
- Decomposition
|
||||
- Construction
|
||||
- Pattern breaking
|
||||
- Interaction
|
||||
|
||||
### Cartesian Coordinates
|
||||
|
||||
_Processing_ lang functions:
|
||||
|
||||
```processing
|
||||
/*
|
||||
* Define basic canvas
|
||||
* createCanvas(width, height);
|
||||
*/
|
||||
createCanvas(400, 400);
|
||||
```
|
||||
|
||||
```processing
|
||||
/*
|
||||
* Define a line on a given canvas
|
||||
* line(x1, y1, x2, y2);
|
||||
*/
|
||||
line(1, 0, 4, 5);
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
**Basic shapes**:
|
||||
|
||||
- Line - `line`
|
||||
- Rectangle - `rect(x, y, width, heigh)`
|
||||
- Circle - `circle(x, y, radius)`
|
||||
- Quadrilateral
|
||||
- Elipse
|
||||
- Circle
|
||||
|
||||
**Colors**:
|
||||
|
||||
- Grayscale: 1byte
|
||||
|
||||
| 0 | 32 | 64 | 96 | 128 | 160 | 196 | 255 |
|
||||
| --- | --- | --- | --- | --- | --- | --- | --- |
|
||||
|
||||
**Programming Languages**:
|
||||
|
||||
- _GPL_ (General Purpose Programming Language)
|
||||
- _DSL_ (Domain Specific Languages)
|
||||
- _Language Workbenches_ (IDE for making languages)
|
||||
@ -0,0 +1,93 @@
|
||||
# Introduction to Computer Science
|
||||
#### > [Jump to Lecture 1](#lecture-1)
|
||||
|
||||
Tehnical course, introducing technologies used all across computer science.
|
||||
* **Professors**: Lin Wang, Balakrishnan Chandrasekaran (working in Networking & Security)
|
||||
* **Contact**: introcs.vu.nl@gmail.com (rules on Canvas)
|
||||
|
||||
#### Goals
|
||||
1. Understand the basics of CS
|
||||
2. Learn how to use programming tools more effectively
|
||||
|
||||
## Course structure
|
||||
#### Lectures
|
||||
(weeks 1-6)
|
||||
|
||||
#### Tutorials
|
||||
(weeks 1-7)
|
||||
<br>
|
||||
Week 7 @ *HG-KC07*
|
||||
|
||||
#### Exam
|
||||
**October 19 Thursday, 12:15 - 14:30** @ TenT
|
||||
|
||||
## Content
|
||||
1. Linux & shell
|
||||
2. Shell scripting
|
||||
3. Build system and Make
|
||||
4. Version control + git
|
||||
5. Working remotely
|
||||
6. MD + LaTeX
|
||||
|
||||
## Assessment
|
||||
* Quizes **[ 20% ]**
|
||||
<br> Avg **6.5** on all quizes
|
||||
<br> Only **1 chance** to submit
|
||||
|
||||
* Assignments **[ 30% ]**
|
||||
<br> Avg **5.5** on each assignment
|
||||
<br> Avg **6.5** across **all** assignments
|
||||
<br> **!!! Limited number of attempts: 3**
|
||||
|
||||
* Final exam **[ 50% ]**
|
||||
<br> Min score is **6.0**
|
||||
<br>
|
||||
|
||||
No resit opportunities.
|
||||
|
||||
<br>
|
||||
|
||||
# Lecture 1
|
||||
|
||||
## What are computers about
|
||||
**Apps:** Web, Apps, Bioinformatics
|
||||
<br>**Theory:** algorithms and comp. complexity
|
||||
<br>**Programming and software:** programming languages, compilers, databases
|
||||
<br>**Coputer systems:** operating systems, networking, distributed systems,
|
||||
mobiled and embedded systems
|
||||
<br>**Hardware:** processor, mother board etc...
|
||||
|
||||
## Hardware
|
||||
* Input (i.e peripherals)
|
||||
* Output (i.e monitor, speaker, printer...)
|
||||
* Compute (i.e CPU, GPU, FPU - math with decimals)
|
||||
* Storage (i.e memory ram, disks)
|
||||
* Networking (i.e ethernet NICs, wifi, bluetooth)
|
||||
|
||||
## Computer Systems
|
||||
#### Operating system
|
||||
* OS kernel
|
||||
<br> Manages the hardware resources
|
||||
<br> Interface for applications to access hardware
|
||||
|
||||
* Utilities for UI
|
||||
|
||||
#### Computer Networking
|
||||
* **Forms**: wired, optical, wifi, bluetooth
|
||||
* **Core concepts**: Ethernet, TCP/IP, switching, routing, congestion, DNS
|
||||
|
||||
#### Distributed systems
|
||||
* Super computers (i.e HPE Frontier)
|
||||
* Data centers (cloud)
|
||||
* Peer-to-peer systems (i.e blockchain)
|
||||
|
||||
#### Mobile and Embedded systems
|
||||
* Small devices (i.e microcontrollers, RespberryPi)
|
||||
* Cyber-physical systems (CPS), Internet-of-Things (IoT)
|
||||
|
||||
## Theoretical computer science
|
||||
|
||||
### Algorithms and computation complexity
|
||||
* Judges how hard a problem is
|
||||
* Big O notation
|
||||
* Turing machine, P vs NP, graph theory ...
|
||||
@ -0,0 +1,98 @@
|
||||
# Operating systems
|
||||
An operating system is **system software** that manages computer hardware,
|
||||
software resources and provides common services for computer programs
|
||||
|
||||
* The operating system takes care of managing hardware by displaying a user
|
||||
interface via shell or GUI
|
||||
|
||||
# History of computers
|
||||
|
||||
### First computer design in the word - Analytical engine
|
||||
* Purely mechanical and intended to do math
|
||||
* Supposed to be made of brass & steam powered
|
||||
* *Difference Engine* ->
|
||||
computing values of polynomial functions fell through
|
||||
|
||||
### First programmable computer - ENIAC
|
||||
* 1945
|
||||
|
||||
### First programmer - Ada Lovelace
|
||||
* 1815 - 1852
|
||||
* Diagram for an algorithm to calculate a sequence of Bernoulli numbers,
|
||||
intended to be carried out by the *Analyitical Engine*
|
||||
|
||||
### First generation
|
||||
* 1945 - 1955
|
||||
* **Technology**: vacuum tubes
|
||||
* Programming: switches
|
||||
* Programming languages: machine code
|
||||
* Tasks: tables of sin, cosin, log
|
||||
* **No OS**
|
||||
|
||||
### Second generatiin
|
||||
* 1955 - 1965
|
||||
* **Technology**: transistors
|
||||
* Programming: punchcards
|
||||
* Language: *FORTRAN*, Assembly
|
||||
* Tasks: scientific computing
|
||||
* Computer: mainframes
|
||||
* OS: batch systems
|
||||
<br>
|
||||
|
||||
At this time universities starting using and buying computers
|
||||
|
||||
### Third generation
|
||||
* **Technology**: integrated circuits (ICs)
|
||||
* Programming: punchcards
|
||||
* Language: *FORTRAN*, Assembly
|
||||
* Tasks: scientific + **commercial**
|
||||
* Computers: **IBM 360**, DEC PDPs
|
||||
* OS: multiprogramming / time-sharing, spooling
|
||||
<br>
|
||||
|
||||
Example OSes: MULTICS (father of all modern OSes), **UNIX (System V, BSD)**
|
||||
<br>
|
||||
|
||||
*There is no reason people would want a computer at home*
|
||||
|
||||
#### Multics
|
||||
[Time-sharing OS](https://github.com/BAN-AI-Multics) developed for mainframes (1963 - 1969)
|
||||
* MIT, GE & Bell Labs
|
||||
* Overdesigned and overbuilt
|
||||
|
||||
#### UNIX
|
||||
* Originally called *Unics*
|
||||
* Influenced most modern OSes
|
||||
* Designed by Ken Thompson, Dennis Ritchie
|
||||
* Rewritten in C (1973), originally in ASM
|
||||
* C lang (created in 1970s)
|
||||
|
||||
**UNIX PHILOSOPHY**: *Build lots of **small** tools, each of which does
|
||||
**exactly one thing well**, but which can be combined to do more powerful
|
||||
things*
|
||||
<br> KISS - Keep It Stupid Simple
|
||||
|
||||
### Fourth generation (1980 - present)
|
||||
* **Technology**: Very large scale integration
|
||||
* Programming: high-level lang
|
||||
* Lang: C/C++, Java, Python etc...
|
||||
|
||||
|
||||
# Linux
|
||||
### Shell
|
||||
A computer program that interprets your commands and sends them to the OS
|
||||
* CLI: a text-based interface for interacting with the Shell
|
||||
* Variants: **sh**, **bash**, **csh**, **zsh**, **fish**
|
||||
|
||||
### Commands
|
||||
* `$ which BINARY_PATH` - path to runnable binary
|
||||
* `$ pwd` - print working directory
|
||||
* `$ env` - list all environment variables
|
||||
* `$ echo` - print
|
||||
* `$ ls` - list files in directory
|
||||
* `$ touch` - create empty file
|
||||
* `$ cat` - concats files
|
||||
* `$ cp` - copy
|
||||
* `$ mv` - move
|
||||
* `$ wc` - word count
|
||||
* `$ grep` - regex matcher magic
|
||||
@ -0,0 +1,58 @@
|
||||
# What AI errors could tell you about bias & inclusivity
|
||||
|
||||
- Ai detects **99%** of patients at risk and **99%** of risk-free patients
|
||||
|
||||
# When it detects a petient at risk, what are the chances of error?
|
||||
|
||||
Table of contents:
|
||||
|
||||
| TP | TN | FP | FN |
|
||||
| ------------- | ------------- | -------------- | -------------- |
|
||||
| True positive | True negative | False positive | False negative |
|
||||
|
||||
| \* | Actually possitive | Actually negative |
|
||||
| ------------------- | ------------------ | ----------------- |
|
||||
| Classfied Positive | True Positive | False Positive |
|
||||
| Classified Negative | False Negative | True Negative |
|
||||
|
||||
## Beware of precision
|
||||
|
||||
If class proportions vary, precision varies.
|
||||
|
||||
$$ Precision = {TP \over TP+FP} $$
|
||||
|
||||
## Beware of accuracy
|
||||
|
||||
Large errors may remain undetected
|
||||
|
||||
$$
|
||||
Accuracy = { TP + TN \over TP + TN + FP + FN }
|
||||
$$
|
||||
|
||||
<br>
|
||||
|
||||
$$
|
||||
TP Rate = { TP \over TP + FN }
|
||||
$$
|
||||
|
||||
# Tuning errors
|
||||
|
||||
## Tuning classification errors
|
||||
|
||||
**Test sets** contain examples of correct classifications, to measure errors.
|
||||
|
||||
- Making use of a data score to balance errors between classes - **tuning parameters**
|
||||
- Needs to use a **treshold**
|
||||
- Often there is a tradeoff to be made in order to adjust the results
|
||||
|
||||
## Visualising errors
|
||||
|
||||
- Roc curves
|
||||
- Confusion Matrix
|
||||
- Classes for multiclass
|
||||
|
||||
## Global error rates
|
||||
|
||||
- Assigning **risk scors** to different people
|
||||
- Github visualisation: [click](https://github.com/pyladiesams/classification-bias-beginner-apr2021)
|
||||
- Errors randomly vary. We can draw confience intervals to show ranges of error to expect in practice
|
||||
@ -0,0 +1,169 @@
|
||||
# Shell
|
||||
|
||||
## sort
|
||||
|
||||
- Start with the 3rd column, then the 2nd column, then the 1st column
|
||||
<br>
|
||||
`sort -t',' -k3,3 -k1,1 -k2,2 columns.txt`
|
||||
- `-v` - verbose
|
||||
|
||||
## uniq
|
||||
|
||||
Deletes duplicates
|
||||
|
||||
## tr
|
||||
|
||||
Convert what is in the first set to what is in the second test
|
||||
|
||||
## Sed
|
||||
|
||||
Replace regex strings
|
||||
<br>
|
||||
`sed "s/i/*/` - Replaces all _i_ with _\*_
|
||||
`sed -i $OPT /path/to/file` - replace in file
|
||||
|
||||
# Module 2 - Shell text wrangling
|
||||
|
||||
**Table of contents**:
|
||||
|
||||
- Combine commands with _redirection_
|
||||
- Declare complex patterns with regular expressions (_regex_)
|
||||
- Data manipulation with redirection and regex
|
||||
|
||||
## Redirection
|
||||
|
||||
1. Reading from files `FILE -> SHELL`
|
||||
2. Writing to files `SHELL -> FILE`
|
||||
3. Piping between commands `SHELL -> SHELL`
|
||||
|
||||
## I/O in Unix
|
||||
|
||||
- Standard input `/dev/stdin`
|
||||
- Standard output `/dev/stdout`
|
||||
- Standard error `/dev/stderr`
|
||||
|
||||
## Ways to redirect input
|
||||
|
||||
1. Redirecting input with `<`
|
||||
<br>`$ cat < alpha.txt`
|
||||
<br>`$ uniq < alpha.txt`
|
||||
<br>`$ tr 'a-z' 'A-Z' < alpha.txt`
|
||||
|
||||
2. Redirecting input with `>`
|
||||
<br>`$ echo 'Hello, world!' > hello.txt`
|
||||
<br>_Appending_ can be done with `>>`
|
||||
<br>`$ echo 'Some other text' >> hello.txt`
|
||||
<br>`$ cat > alpha.txt` - _fancy (kek)_ text editor
|
||||
|
||||
3. Redirecting **normal output** and **errors**
|
||||
|
||||
- **Normal output**: `1>` (`1>` equivalent to `>`)
|
||||
- **Error output**: `2>`
|
||||
|
||||
<br>`$echo 'Hello world' 1>output.txt 2>error.txt`
|
||||
|
||||
4. Redirecting output and error to the same file
|
||||
|
||||
- Using: `> file.txt 2>&1`
|
||||
- `&>` is the simpler **equivalent**
|
||||
|
||||
<br>`$ echo 'Hello, world! > file.txt 2>&1`
|
||||
<br>`$ cat /dev/null` - empty _black hole_ file
|
||||
<br>`$ wc file.txt 2>/dev/null` - redirects errors to `/dev/null`
|
||||
|
||||
## Piping between commands
|
||||
|
||||
Takes the **output** from one command and redirects it to the **input** of another command
|
||||
|
||||
##### !!! IMPORTANT
|
||||
|
||||
Commands that are called using `|` run **concurrently**! They are separated on different processes and the shell picks which command should start first
|
||||
|
||||
<br>**Example:**
|
||||
|
||||
```bash
|
||||
$ cat hello.txt | sort
|
||||
```
|
||||
|
||||
## RegEx
|
||||
|
||||
- `.` - any single character
|
||||
- `[abc]` - any character inside []
|
||||
- `[a-z]` - any character in range a-z
|
||||
- `[^a-z]` - any character not in range a-z
|
||||
- `(a|b)` - either a or b
|
||||
|
||||
**Quantifiers**:
|
||||
|
||||
- `*` means we want 0 or more characters of the specified kind
|
||||
- `+` 1 or more characters of the specified kind
|
||||
- `?` exactly 0 or 1 characters of the specified kind
|
||||
- `{X}` means we want exactly **X characters** of the specified kind
|
||||
- `{X,Y}` means we want **X to Y** characters of the specified kind
|
||||
|
||||
**Anchors**:
|
||||
|
||||
- `^` specifies the start of the line
|
||||
- `$` specifies the end of the line
|
||||
|
||||
**Example:**
|
||||
<br>`[a-zA-Z0-9\.-+-%_]+@([a-zA-Z]+\.)+[a-z]{2,4}`
|
||||
|
||||
## Data manipulation
|
||||
|
||||
- `grep 'REGEX' file_name` - basic regular expression (BRE)
|
||||
- `grep -E 'REGEX' file_name` - extended regular expression (ERE)
|
||||
- **!!!** `\b` - search for word boundary
|
||||
|
||||
## RegEx with sed
|
||||
|
||||
- `sed -E 's/REGEX/SUBSTITUTION/FLAGS'`
|
||||
- `sed` can use capture groups
|
||||
- `$ sed -E 's/\bmo\b/mom/g`
|
||||
- `$ sed 's/[aeiou]/***/g`
|
||||
- `$ sed 's/(capture group 1)(capture group 2)/**\1***\2/g`
|
||||
- `$ echo "nicer" | sed -E "s/([^aeiou])([a-z]+)([^aeiou])/\1****\3/g"` - run this :)
|
||||
|
||||
## Awk
|
||||
|
||||
`$ awk -F "\t" '$2>$3 {print $1}' log.txt`
|
||||
|
||||
- `-F` - use tab `\t`
|
||||
- `$2>$3` - **pattern**: second field is larger than 23
|
||||
- `{print $1}` - **action**: print the first field
|
||||
- `file.txt` - input file
|
||||
|
||||
**Binary operators**:
|
||||
|
||||
- `+` addition
|
||||
- `-` subtraction
|
||||
- `*` manipulation
|
||||
- `/` division
|
||||
|
||||
**Conditional expressions**:
|
||||
|
||||
- `==` is equal
|
||||
- all rest like C++
|
||||
|
||||
**RegEx**:
|
||||
|
||||
- `~` matches
|
||||
- `!~` does not match
|
||||
|
||||
**Boolean operators**:
|
||||
|
||||
- `&&` and
|
||||
- `||` or
|
||||
- `!` not
|
||||
|
||||
**Others**:
|
||||
|
||||
- `$0` full record
|
||||
- `$1` specify field 1
|
||||
- `FS` input field separator
|
||||
- `OFS` output field separator
|
||||
- `NF` number of fields
|
||||
- `NR` number of records
|
||||
|
||||
**Example**:
|
||||
<br>`$ awk -F "\t" '$0 !~ /^[A#]/ && $3 == "udp" && $2 > 22 {print $1}' log.txt`
|
||||
@ -0,0 +1,231 @@
|
||||
# Bash scripting part 2
|
||||
|
||||
# Loops
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
for VAR in {1..5}
|
||||
do
|
||||
echo "VAR is set to $VAR"
|
||||
done
|
||||
```
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
for VAR in 1 2 3 4 5
|
||||
do
|
||||
echo "VAR is set to $VAR"
|
||||
done
|
||||
```
|
||||
|
||||
Wildcard `*`
|
||||
|
||||
```bash
|
||||
for VAR in 1 * 2 bye
|
||||
do
|
||||
echo "VAR is set to $VAR"
|
||||
done
|
||||
```
|
||||
|
||||
```bash
|
||||
for VAR in 1*2 bye
|
||||
do
|
||||
echo "VAR is set to $VAR"
|
||||
done
|
||||
```
|
||||
|
||||
Similar to C loops:
|
||||
|
||||
```bash
|
||||
for (( i = 1; i <= input; ++i ))
|
||||
do
|
||||
echo "VAR IS SET TO $i"
|
||||
done
|
||||
```
|
||||
|
||||
# While loops
|
||||
|
||||
General syntax:
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
while [ CONDITION ]
|
||||
do
|
||||
# Do something
|
||||
done
|
||||
```
|
||||
|
||||
Example:
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env/bash
|
||||
|
||||
num=0
|
||||
while [ $num -lt 50 ] # num < 50
|
||||
do
|
||||
echo $num
|
||||
num=$(( num + 1 ))
|
||||
done
|
||||
```
|
||||
|
||||
Always evaluates to true (while true):
|
||||
<br>Exit with `break` keyword
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
|
||||
read input
|
||||
|
||||
while:
|
||||
do
|
||||
if [[ "$input" = "bye" ]]; then
|
||||
then
|
||||
echo "Byebye"
|
||||
break
|
||||
fi
|
||||
read input
|
||||
done
|
||||
```
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
|
||||
read input
|
||||
|
||||
while [[ "$input" = "hi" ]]
|
||||
do
|
||||
if [[ "$input" = "bye" ]]; then
|
||||
then
|
||||
echo "Byebye"
|
||||
continue
|
||||
fi
|
||||
read input
|
||||
done
|
||||
```
|
||||
|
||||
# Arguments and functions
|
||||
|
||||
`$ bash large_number.sh 101 102`
|
||||
<br> large_number.sh -> arg0 `$0`
|
||||
<br> 101 -> arg1 `$1`
|
||||
<br> 102 -> arg2 `$2`
|
||||
|
||||
```bash
|
||||
#!/bin/bash
|
||||
|
||||
num1=$1 # Argument 1
|
||||
num2=$2 # Argument 2
|
||||
|
||||
if [ num1 -gt num2 ];
|
||||
then
|
||||
echo $num1
|
||||
else
|
||||
echo $num2
|
||||
fi
|
||||
```
|
||||
|
||||
### Useful args
|
||||
|
||||
- `$0` -> name of the script
|
||||
- `$@` -> all aruments
|
||||
- `$#` -> number of arguments
|
||||
- `$?` -> return code of the previous command
|
||||
- `$$` -> PID of the current command
|
||||
- `!!` -> entire last command with arguments
|
||||
- `$_` -> last argument of last command
|
||||
|
||||
# Functions
|
||||
|
||||
Variable scope:
|
||||
|
||||
```bash
|
||||
#!/bin/bash
|
||||
|
||||
# define a user function
|
||||
make_and_enter() {
|
||||
mkdir -p "$1"
|
||||
cd "$1"
|
||||
}
|
||||
|
||||
make_and_enter new_folder
|
||||
```
|
||||
|
||||
**USEFUL NOTE**: Scopes in bash are `inline`, functions do not create their one scopes, therefore variables are kept between functions.
|
||||
<br> However, if a function is _piped_, a new shell is created to execute the command. Creating a new shell does not preserve variables, as a new shell creates a new scope.
|
||||
<br> **Scopes** in bash are defined by different shells running concurrently.
|
||||
|
||||
### Return values
|
||||
|
||||
Return values are noted as **exit codes**, which allow the user to verify the success or failure of a previous command.
|
||||
<br>In bash, a return value of 0 means **success**. A return value other than 0 (1-255) suggests that an error occured.
|
||||
|
||||
- `$?` -> Return value of previous command
|
||||
- `true` -> command that does nothing except return an exit status of 0
|
||||
- `false` -> command that does nothing except return an exit status of 1
|
||||
|
||||
```bash
|
||||
#!/usr/bin/env bash
|
||||
|
||||
cat my_file 1>/dev/null 2>&1
|
||||
|
||||
if [ $? -ne 0 ];
|
||||
then
|
||||
echo "File exists"
|
||||
else
|
||||
echo "File does not exist"
|
||||
fi
|
||||
```
|
||||
|
||||
### Testing command validity - another approach
|
||||
|
||||
```bash
|
||||
cat my_file &>/dev/null && echo "File exists"
|
||||
cat my_file &>/dev/null || echo "File does not exist"
|
||||
```
|
||||
|
||||
# Command substitution
|
||||
|
||||
Two ways:
|
||||
|
||||
1. $(command)
|
||||
2. \`command\`
|
||||
|
||||
# Arrays
|
||||
|
||||
```bash
|
||||
#!/bin/bash
|
||||
|
||||
# define an array
|
||||
odd_num=(2 4 6 8 10 12)
|
||||
|
||||
# retrieve first element
|
||||
${odd_num[0]}
|
||||
|
||||
# append new elements
|
||||
odd_num+=(2 14)
|
||||
```
|
||||
|
||||
# Awk advanced
|
||||
|
||||
## Control flows in `awk`
|
||||
|
||||
```
|
||||
CS,30,1
|
||||
EE,40,2
|
||||
AI,35,1
|
||||
```
|
||||
|
||||
```awk
|
||||
#!/usr/bin/env bash
|
||||
|
||||
awk `
|
||||
BEGIN { FS =","; count=0; total=-0}
|
||||
$1 == subject { count++; total += $2 }
|
||||
END { if (count == 0) {print "No entry"}
|
||||
else { average = total / count
|
||||
print "Average: ", average
|
||||
}
|
||||
}
|
||||
subject="$1" record.txt
|
||||
`
|
||||
```
|
||||
Loading…
Reference in new issue