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2,300 | string indexing each character in string has numbered position called an index you can access the character at the nth position by putting the number between two square brackets ([]immediately after the stringflavor "fig pieflavor[ 'iflavor[ returns the character at position in "fig pie"which is wait isn' the first cha... |
2,301 | if you try to access an index beyond the end of stringthen python raises an indexerrorflavor[ traceback (most recent call last)file ""line in flavor[ indexerrorstring index out of range the largest index in string is always one less than the string' length since "fig piehas length of seventhe largest index allowed is s... |
2,302 | for examplesuppose string input by user is assigned to the variable user_input if you need to get the last character of the stringhow do you know what index to useone way to get the last character of string is to calculate the final index using len()final_index len(user_input last_character user_input[final_indexgettin... |
2,303 | flavor[ : returns the first three characters of the string assigned to flavorstarting with the character at index and going up to but not including the character at index the [ : part of flavor[ : is called slice in this caseit returns slice of "fig pieyumstring slices can be confusing because the substring returned by... |
2,304 | whose index is the first number in the slice and ends with the last character in the stringflavor[ :piefor "fig pie"the slice [ :is equivalent to the slice [ : since the character at index is spaceflavor[ : returns the substring that starts with the space and ends with the last letterpieif you omit both the first and s... |
2,305 | note the empty string is called empty because it doesn' contain any characters you can create it by writing two quotation marks with nothing between themempty_string " string with anything in it--even space--is not empty all the following strings are non-emptynon_empty_string non_empty_string non_empty_string even thou... |
2,306 | instead of returning the entire string[- : returns the empty stringflavor[- : 'this happens because the second number in slice must correspond to boundary that is to the right of the boundary corresponding to the first numberbut both - and correspond to the leftmost boundary in the figure if you need to include the fin... |
2,307 | python throws typeerror and tells you that str objects don' support item assignment if you want to alter stringthen you must create an entirely new string to change the string "goalto the string "foal"you can use string slice to concatenate the letter "fwith everything but the first letter of the word "goal"word "goalw... |
2,308 | manipulate strings with methods manipulate strings with methods strings come bundled with special functions called string methods that you can use to work with and manipulate strings there are numerous string methods availablebut we'll focus on some of the most commonly used ones in this sectionyou'll learn how toconve... |
2,309 | string methods don' just work on string literals you can also use lower(on string assigned to variablename "jean-luc picardname lower('jean-luc picardthe opposite of lower(is upper()which converts every character in string to uppercasename upper('jean-luc picardcompare the upper(and lower(string methods to the len(func... |
2,310 | there are three string methods that you can use to remove whitespace from string rstrip( lstrip( strip(rstrip(removes whitespace from the right side of stringname "jean-luc picard name 'jean-luc picard name rstrip('jean-luc picardin this examplethe string "jean-luc picard has five trailing spaces you use rstrip(to remo... |
2,311 | it' important to note that none of rstrip()lstrip()or strip(removes whitespace from the middle of the string in each of the previous examplesthe space between "jean-lucand "picardis preserved determine if string starts or ends with particular string when you work with textsometimes you need to determine if given string... |
2,312 | just like startswith()the endswith(method is case sensitivestarship endswith("rise"false note the true and false values are not strings they are special kind of data type called boolean value you'll learn more about boolean values in string methods and immutability recall from the previous section that strings are immu... |
2,313 | use idle to discover additional string methods strings have lots of methods associated with themand the methods introduced in this section barely scratch the surface idle can help you find new string methods to see howfirst assign string literal to variable in the interactive windowstarship "enterprisenexttype starship... |
2,314 | write program that removes whitespace from the following stringsthen print out the strings with the whitespace removedstring filet mignonstring "brisket string cheeseburger write program that prints out the result of startswith("be"on each of the following stringsstring "becomesstring "becomesstring "bearstring beautif... |
2,315 | go ahead and type some text and press enter input(hello there'hello there!the text you entered is repeated on new line with single quotes that' because input(returns as string any text entered by the user to make input( bit more user-friendlyyou can give it prompt to display to the user the prompt is just string that y... |
2,316 | here' sample run of the programheywhat' upmind your own business you saidmind your own business once you have input from useryou can do something with it for examplethe following program takes user inputconverts it to uppercase with upper()and prints the resultresponse input("what should shout"shouted_response response... |
2,317 | challengepick apart your user' input write program named first_letter py that prompts the user for input with the string "tell me your password:the program should then determine the first letter of the user' inputconvert that letter to uppercaseand display it back for exampleif the user input is "no"then the program sh... |
2,318 | actual numbers for instancetry this bit of code out in idle' interactive windownum " num num ' the operator concatenates two strings togetherwhich is why the result of " " is " and not " you can multiply strings by number as long as that number is an integer or whole number type the following into the interactive windo... |
2,319 | type " " in the interactive window and press enter " " traceback (most recent call last)file ""line in typeerrorcan' multiply sequence by non-int of type 'strpython raises typeerror and tells you that you can' multiply sequence by non-integer note sequence is any python object that supports accessing elements by index ... |
2,320 | converting strings to numbers the typeerror examples in the previous section highlight common problem when applying user input to an operation that requires number and not stringtype mismatches let' look at an example save and run the following programnum input("enter number to be doubled"doubled_num num print(doubled_... |
2,321 | try converting the string " to an integerint(" "traceback (most recent call last)file ""line in valueerrorinvalid literal for int(with base ' even though the extra after the decimal place doesn' add any value to the numberpython won' change into because it would result in loss of precision let' revisit the program from... |
2,322 | as you've already seenconcatenating number with string produces typeerrornum_pancakes " am going to eat num_pancakes pancakes traceback (most recent call last)file ""line in typeerrorcan only concatenate str (not "int"to str since num_pancakes is numberpython can' concatenate it with the string " ' going to eatto build... |
2,323 | review exercises you can nd the solutions to these exercises and many other bonus resources online at realpython com/python-basics/resources create string containing an integerthen convert that string into an actual integer object using int(test that your new object is number by multiplying it by another number and dis... |
2,324 | known as -strings the easiest way to understand -strings is to see them in action here' what the above string looks like when written as an -stringf"{namehas {headsheads and {armsarms'zaphod has heads and armsthere are two important things to notice about the above example the string literal starts with the letter befo... |
2,325 | overleaf is web-bases latexsystemmeaning you can write your latexdocuments in your web browseryou co-work and share documents with others for more information about overleafpython books you find other python textbooks within different domains on my python web pagepython bookspython programming this is textbook in pytho... |
2,326 | the way we create software today has changed dramatically the last yearsfrom the childhood of personal computers in the early to today' powerful devices such as smartphonestablets and pcs the internet has also changed the way we use devices and software we still have traditional desktop applicationsbut web sitesweb app... |
2,327 | getting started with python introduction the new age of programming matlab what is python introduction to python interpreted vs compiled python packages python packages for science and numerical computations anaconda python editors python idle visual studio code spyder visual studio pycharm wing python ide jupyter note... |
2,328 | run python scripts from spyder basic python programming basic python program get help variables numbers strings string input built-in functions python standard library using python librariespackages and modules python packages plotting in python subplots exercises ii python programming python programming if else arrays... |
2,329 | introduction to error handling syntax errors exceptions exceptions handling debugging in python installing and using python packages what is pip iii python environments and distributions introduction to python environments and distributions package and environment managers pip conda python virtual environments anaconda... |
2,330 | python for mathematics applications mathematics in python basic math functions exercises statistics introduction to statistics statistics functions in python trigonometric functions polynomials vi resources python resources python distributions python libraries python editors python tutorials python in visual studio vi... |
2,331 | getting started with python |
2,332 | introduction with this textbook you will learn basic python programming the textbook contains lots of examples and self-paced tasks that the users should go through and solve in their own pace you will find additional resources on my blog/web site [ my web site about python issee figure the new age of programming the w... |
2,333 | python is fairly old programming language ( compared to many other programming languages like ( )swift ( )java ( )php ( python has during the last years become more and more popular todaypython has become one of the most popular programming languages there are many different rankings regarding which programming languag... |
2,334 | mobile enterprise embedded according to figure we see that python can be used to program web applicationsenterprise applications and embedded applications so far python is not used or not optimized for creating mobile applications we have today major mobile platformsios applications are mainly programmed with the swift... |
2,335 | python is highly extendable due to its high number of free available python packaged and libraries python can be used on all platforms (windowsmacos and linuxpython is multi-purpose and can be used for to program web applicationsenterprise applications and embedded applicationsand within data science and engineering ap... |
2,336 | databases (such as sql server and mysqland using the structured query language (sqlor the upcoming nosql databases app development for the main platforms ios (xcode using the swift programming languageand android (android studio using the java programming language or kotlin programming languageif you have skills in mos... |
2,337 | |
2,338 | what is python introduction to python python is an open source and cross-platform programming languagethat has become increasingly popular over the last ten years it was first released in latest version is cpython is the reference implementation of the python programming language written in ccpython is the default and ... |
2,339 | you write python pyfiles in text editor and then put those files into the python interpreter to be executed depending on the editor you are usingthis is either done automaticallyor you need to do it manually here are some important python sources[ ][ ][ interpreted vs compiled what are the differences between interpret... |
2,340 | interpreted programs must be reduced to machine instructions at run-time it is usually easier to develop applications in an interpreted environment because you don' have to recompile your application each time you want to test small section python is an interpreted programming languagewhile / +are translated by running... |
2,341 | to usee distribution package like anacondawhere you typically get the packages you need for scientific computing with anaconda you typically get the same features as with matlab lots of python packages existsdepending on what you are going to solve we have python packages for desktop gui developmentdatabase development... |
2,342 | webwikipediaspyder and the python packages (numpyscipymatplotlibmention above ++are included in the anaconda distribution python editors an editor is program where you create your code (and where you can run and test itmost editors have also features for debugging for simple python programs you can use the idle editorb... |
2,343 | visual studio code visual studio code is source code editor developed by microsoft for windowslinux and macos webresourcesgetting started with python in visual studio code spyder spyder is an open source cross-platform integrated development environment (idefor scientific programming in the python language webwikipedia... |
2,344 | wing python ide the wing python ide family of integrated development environments (idesfrom wingware were created specifically for the python programming language different version of wing exists [ ]wing very simplified free versionfor teaching beginning programmers wing personal free version that omits some featuresfo... |
2,345 | here you can download the basic python features in one packagewhich includes the python programming language interpreterand basic code editoror an integrated development environmentcalled idle see figure for basic python programming this is good enough for more advanced python programming you typically need better code... |
2,346 | getting started with python in visual studio code |
2,347 | start using python in this we will start to use python in some simple examples python ide the basic code editoror an integrated development environmentcalled idle see figure other python editors will be discussed more in detail later for now you can use the basic python ide (idleor spyder if you have installed the anac... |
2,348 | lets open your python editor and type the following world listing hello world python example [end of examplean extremely useful command is help()which enters help functionality to explore all the stuff python lets you doright from the interpreter press to close the help window and return to the python prompt you can us... |
2,349 | opening the console on macos the standard console on macos is program called terminal open terminal by navigating to applicationsthen utilitiesthen double-click the terminal program you can also easily search for it in the system search tool in the top right the command line terminal is tool for interacting with your c... |
2,350 | opening the console on windows window' console is called the command promptnamed cmd an easy way to get to it is by using the key combination windows+ (windows meaning the windows logo button)which should open run dialog then type cmd and hit enter or click ok you can also search for it from the start menu it should lo... |
2,351 | in the next windowfind and select the user variable named path and click edit to change its value see figure select "newand add the path where "python exeis located see figure the default location iscu \appdatal programs python python - click save and open the command prompt once more and enter "pythonto verify it work... |
2,352 | scripting mode in "scriptingmode you can write python program with multiple python commands and then save it as file pyrun python scripts from the python idle from the python shell you select file new fileor you can open an existing pytho program or python script by selecting file open lets create new script and type i... |
2,353 | the idle editor is very basicfor more complicated tasks you typically may prefer to use another editor like spydervisual studio codeetc run python scripts from the console (terminalmacos from the console (terminalon macos cd username downloads python py notemake sure you are at your system command promptwhich will have... |
2,354 | run python scripts from the command prompt in windows from command prompt in windowcd cd temp python py notemake sure you are at your system command promptwhich will have at the endnot in python mode (which has instead)see also figure then it responds withhello world how you run python scripts from spyder if you have i... |
2,355 | figure running python scripts from console window on macos figure running python scripts from console window on macos |
2,356 | |
2,357 | basic python programming basic python program we will start using python and create some code examples we use the basic idle editor (or another python editorexample hello world example lets open your python editor and type the following world listing hello world python example [end of exampleget help an extremely usefu... |
2,358 | we use the basic idle (or another python editorand type the followingx listing using variables in python here we define variable and sets the value equal to and then print the result to the screen [end of exampleyou can write one command by time in the idle if you quit idle the variables and data are lost thereforeif y... |
2,359 | (sumamountetcyou don need to define the variables before you use them (like you need to to ine / ++/cfigure show these examples using the basic idle editor figure basic python here are some basic rules for python variablesa variable name must start with letter or the underscore character variable name cannot start with... |
2,360 | normal coding you don' need to bother example numeric types in python int float complex listing numeric types in python this means you just assign values to variable without worrying about what kind of data type it is type type type listing check data types in python if you use the spyder editoryou can see the data typ... |
2,361 | upper " "jprint ( ("listing strings in python as you see in the examplethere are many built-in functions form manipulating strings in python the example shows only few of them strings in python are arrays of bytesand we can use index to get specific character within the string as shown in the example code [end of examp... |
2,362 | python standard library python allows you to split your program into modules that can be reused in other python programs it comes with large collection of standard modules that you can use as the basis of your programs the python standard library consists of different modules for handling file /obasic mathematicsetc yo... |
2,363 | im po rt math mt mt print ( [end of examplethere are advantages and disadvantages with the different approaches in your program you may need to use functions from many different modules or packages if you import the whole module instead of just the function(syou need you use more of the computer memory very often we al... |
2,364 | these packages need to be downloaded and installed separatelyor you choose to usee distribution package like anaconda here you find an overview of the numpy libraryhere you find an overview of the scipy libraryhere you find an overview of the matplotlib libraryyou will learn the basics features in all these libraries w... |
2,365 | sin ( print ( sin ( print (yin this case it worksbut assume you have different functions with the same name that have different meaning in different libraries [end of examplepython packages in addition to the python standard librarythere is growing collection of several thousand components (from individual programs and... |
2,366 | plot(title(xlabel(ylabel(axis(grid(subplot(legend(show(lets create some basic plotting examples using the matplotlib libraryexample plotting in python in this example we have to arrays with data we want to plot vs we can assume is time series and is the corresponding temperature degrees celsius im po rt [ , plt plot ( ... |
2,367 | [end of examplewe have used basic plotting function in the matplotlib libraryplot(xlabel(ylabel(show(example plotting sine curve im po rt numpy np im po rt [ np plt plot ( yplt xlabel ' plt ylabel ' show this gives the following plot (see figure ) better solution will then be |
2,368 | im po rt im po rt numpy np xstart np increment np xstop np plt plot ( yplt xlabel ' plt ylabel ' show this gives the following plot (see figure )if you want grids you can use the grid(function [end of examplesubplots the subplot command enables you to display multiple plots in the same window typing "subplot( , , )part... |
2,369 | we will create and plot sin(and cos(in different subplots im po rt im po rt numpy np xstart np increment np xstop np np plt subplot ( , , plt plot ( ' plt sin plt xlabel ' plt ylabel sin (xplt grid ( show plt subplot ( , , plt plot ( plt cos plt xlabel ' plt ylabel cos (xplt grid ( show [end of example |
2,370 | exercises below you find different self-paced exercises that you should go through and solve on your own the only way to learn python is to do lots of exercisesexercise create sin(xand cos(xin different plots create sin(xand cos(xin different plots you should use all the plotting functions listed below in your codeplot... |
2,371 | python programming |
2,372 | python programming we have been through the basics in pythonsuch as variablesusing some basic built-in functionsbasic plottingetc you may come far only using these thinsbut to create real applicationsyou need to know about and use features likeif else for loops while loops arrays if you are familiar with one or more ot... |
2,373 | using if else if bp than belse " than and listing using arrays in python using elif if bp than belif ap " than = blisting using arrays in python notepython uses "elifnot "elseiflike many other programming languages do [end of example arrays an array is special variablewhich can hold more than one value at time here are... |
2,374 | data append data ( data print (xlisting using arrays in python you define an array like this data you can also use text like this volvo ford you can use arrays in loops like this data print (xyou can return the number of elements in the array like this data you can get specific value inside the array like this index ca... |
2,375 | for loops for loop is used for iterating over sequence guess all your programs will use one or more for loops so if you have not used for loops beforemake sure to learn it now below you see basic example how you can use for loop in python in range ( print the for loop is probably one of the most useful feature in pytho... |
2,376 | loop [end of exampleexample using for loops for summation of data you typically want to use for loop for find the sum of given data set data sum #find sum numbers data sum sum sum #find mean average numbers data mean sum/ mean this gives the following results [end of exampleexample implementing fibonacci numbers using ... |
2,377 | recurrence relation fn fn- fn- ( with seed valuesf we will write python script that calculates the first fibonacci numbers the python script becomes like this fib fib print fib print fib ( - + fib fib fib fib next print fib next listing fibonacci numbers using for loop in python alternative solution fib [ ( - + + appen... |
2,378 | ( - + + + print fib listing fibonacci numbers using for loop in python alt another alternative solution im po rt numpy np np ( fib [ fib [ ( - + + + print fib listing fibonacci numbers using for loop in python alt [end of examplenested for loops in python and other programming languages you can use one loop inside anot... |
2,379 | other divisorit cannot be prime natural number ( etc is called prime number (or primeif it is greater than and cannot be written as product of two natural numbers that are both smaller than it create python script where you find all prime numbers between and tipi guess this can be done in many different waysbut one way... |
2,380 | the solution for the differential equation isx(teat ( set = and the initial condition ( )= create script in python py filewhere you plot the solution (tin the time interval < < add gridand proper title and axis labels to the plot [end of exercise |
2,381 | creating functions in python introduction function is block of code which only runs when it is called you can pass dataknown as parametersinto function function can return data as result previously we have been using many of the built-in functions in python if you are familiar with one or more other programming languag... |
2,382 | python have lots of built-in functionsbut very often we need to create our own functions (we could refer to these functions as user-defined functionsin python function is defined using the def keyword functionname return example create function in separate file below you see simple function created in python add return... |
2,383 | example create function in separate file we start by creating separate python file (myfunctions pyfor the function def average ( / listing function calculating the average nextwe create new python file ( testaverage pywhere we use the function we created from im po rt average ( print listing test of average function [e... |
2,384 | data mean data mean listing function with multiple return values [end of example exercises below you find different self-paced exercises that you should go through and solve on your own the only way to learn python is to do lots of exercisesexercise create python function create function calcaverage that finds the aver... |
2,385 | exercise create function that implementing fibonacci numbers fibonacci numbers are used in the analysis of financial marketsin strategies such as fibonacci retracementand are used in computer algorithms such as the fibonacci search technique and the fibonacci heap data structure they also appear in biological settingss... |
2,386 | or not you can check the function in the command window like this number number then python respond with true or false [end of exercise |
2,387 | creating classes in python introduction python is an object oriented programming (ooplanguage almost everything in python is an objectwith its properties and methods the foundation for all object oriented programming (ooplanguages are classes to create classuse the keyword class classname example simple class example w... |
2,388 | more examples [end of exampleexample python class lets create the following python code car model " car model volvo blue model model ford green model listing python class example you should try these examples [end of example the init (function in python all classes have built-in function called init ()which is always e... |
2,389 | car volvo blue model print car listing python class constructor example lets extend the class by defining function as welld car car def init model model model color color def displaycar model print color lets using the class car "red car displaycar ( car ford green model print car car volvo blue model print car =black ... |
2,390 | car "red[end of exampleexercise create the class in separate python file we start by creating the class and then we save the code in "car py" car car def init model model model color color def displaycar model print color listing define python class in separate file then we create python script (testcar pywhere we are ... |
2,391 | exercises below you find different self-paced exercises that you should go through and solve on your own the only way to learn python is to do lots of exercisesexercise create python class create python class where you calculate the degrees in fahrenheit based on the temperature in celsius and vice versa the formula fo... |
2,392 | creating python modules as your program gets longeryou may want to split it into several files for easier maintenance you may also want to use handy function that you have written in several programs without copying its definition into each program to support thispython has way to put definitions in file and use them i... |
2,393 | tc (tf ( / ( firstwe create python module with the following functions (fahrenheit py) tc tf tc tf tf tc tf tc listing fahrenheit functions thenwe create python script for testing the functions (testfahrenheit py) from mp ort tc tf tc tf tf tc tf tc listing python script testing the functions the results becomes fahren... |
2,394 | it is quite easy to convert from radians to degrees or from degrees to radians we have that [radians [degrees( this givesd[degreesr[radiansx ( [radiansd[degreesx ( and create two functions that convert from radians to degrees ( ( )and from degrees to radians ( ( )respectively these functions should be saved in one pyth... |
2,395 | file handling in python introduction python has several functions for creatingreadingupdatingand deleting files the key function for working with files in python is the open(function the open(function takes two parametersfilenameand mode there are four different methods (modesfor opening file"xcreate creates the specif... |
2,396 | "wwrite opens file for writingcreates the file if it does not exist "aappend opens file for appendingcreates the file if it does not exist example write data to file open " data helo world data close (listing write data to file [end of example read data from file to read to an existing fileyou must add the following pa... |
2,397 | data open " data record value write record \ close (listing logging data to file [end of exampleexample read logged data from file open for record in \nprint record close (listing read logged data from file [end of example web resources below you find different useful resources for file handling python file handling sc... |
2,398 | exercise data logging assume you read data from temperature sensor every seconds for period of let say minutes log the data to file you can use the random generator in python an example of how to use the random generator is shown below im po rt random in range ( data random data listing read data from file make sure to... |
2,399 | time value |
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