Ukens læringsmål

• bli kjent med kursets oppsett og ressurser
• kunne jobbe med Jupyter Notebook
• kunne lage og kjøre et enkelt python program
• forstå og kunne bruke noen programmeringselementer
• variabler
• tall og tekst
• import av koden utenfor notebook
• bruk av funksjoner i python
• kunne bruke python for enkle vitenskapelige beregninger

Hvorfor programmering

• datamaskinen er nå essensiell i biologien
• målet er altid å få svar på et biologisk spørsmål
• få dette svaret
• fortere
• mer nøyaktig
• etterprøvbar
• repeterbar

Hvorfor programmering

• biologer trenger å kunne lage programmer selv
• biologer trenger å kunne vurdere resultater kritisk

Hvorfor Python

• brukt mye i vitenskapen og biologien
• attraktiv syntaks
• letter å lære (bort) enn andre språk

Hva er et program

• instruksjoner som sier til datamaskinen hva den skal gjøre
• instruksjoner er linjer med tekst
• datamaskinen gjør nøyaktig det du ber dem om å gjøre

Programmering

1. planlegge koden du trenger
2. skrive koden
3. kjøre koden og sjekke resultater
4. korrigere koden (debugging)

Hvordan python

• Jupyter Notebook

DEMO av Jupyter Notebook

Ukens programmeringsbegreper

• variabler og type variabler
• tall og tekst
• regne i python (med og uten variabler)
• import av koden utenfor notebook
• bruk av funksjoner i python

Hjertefrekvens

The target heart rate (HR) $$ \text{HR}_{\text{max}} = 220 - \text{age} $$

Hjertefrekvens

The target heart rate for a specific intensity:

Multiply the maximum heart rate with the given intensity $$ \text{HR}_\text{target} = \text{HR}_\text{max} \times \text{intensity} = (220 - \text{age}) \times \text{intensity} $$

Fahrenheit to Celsius

If \( F \) is the temperature in Fahrenheit, and \( C \) is the temperature in Celsius, this conversion between them is made by the formula, $$ \begin{equation} C = (F-32)/1.8\;. \label{_auto1} \end{equation} $$

Mathematical functions

Some of the most common mathematical functions in the pylab package:

A simple temperature model

The average temperature, measured in degrees Celsius, during the course of a year in Oslo, the capital of Norway, is modeled fairly well by the expression $$ \begin{equation} T(x) = 6 + 10\sin\left({2\pi \over 365} x - 1.9\right), \label{_auto2} \end{equation} $$ where

• \( T \) is the average temperature
• \( x \) is time, measured in days
• \( x=1 \) is January 1st, and so on

Math and code

$$ \begin{equation} T(x) = 6 + 10\sin\left({2\pi \over 365} x - 1.9\right), \label{_auto3} \end{equation} $$ where

• \( T \) is the average temperature
• \( x \) is time, measured in days
• \( x=1 \) is January 1st, and so on

from pylab import *

x = 100                           # day of the year
T = 6 + 10*sin(2*pi*x/365 - 1.9)  # average temperature (in Celsius)

print("Average temperature on day", x, ":", T, "degrees Celsius")

Summary

Variables

• Data is stored in variables
• This is called assignment
• Variables make it possible for us to give the data a name, which can be used to access the data later in our program
• Good variable names make the code easier to read

Types of variables

• There are several types of variables in Python
• We have been working on the following types
• Floats
• Integers
• Strings

Functions

• A function is a piece of previously defined code
• Either by yourself or others that
• Functions perform specific tasks
• A function can take zero, one or multiple arguments as input (inside the parenthesis) and may return a value
• When in a Jupyter Notebook you can get information about any function by writing the name of the function followed by a question mark, ?

Order of operations

When performing multiple operations in a single line of code the order in which the operations are performed is the following:

1. First, we calculate everything inside parentheses,
2. then we do all function calls,
3. then we do all powers,
4. then we do all multiplications and divisions,
5. finally, we do all additions and subtractions.

Comments

• The main point of comments is to make the program easier to read
• They begin with a hashtag and everything after this character is ignored when the program is run

Packages

• A package is a collection of functions for performing specific tasks that we can use
• A package that contains many functions we need for scientific calculations, is named pylab