Formatting Output

Line Endings• By now, you’ve noticed that the print( ) function will

automatically print out a new line after passing all of the arguments

• However, you can avoid this by changing the end behavior inside the print function

Example:

print ( “one”, end = “” )

print ( “two”, end = “” )

>> onetwo

Line Endings• It turns out, you can actually ask the print

function to add whatever you’d like at the end of it’s execution

print (“one”, end = “***” )

print (“two”, end = “ ” )

print (“three”, end = “ (: ” )

>> one***two three (:

Separating Arguments •By now, you should’ve also noticed that the

print function prints a space in between each argument that is passed through it

• This can also be avoided as well by a “sep” command in the print function

Example:

print (“one”, “two”, sep = “” )

>> onetwo

Separating Arguments More Examples:

print (“hello world”, “!”, “?”, sep = “” )

>> hello world!?

print (“one”, “two”, “three”, sep = “*” )

>> one*two*three

Combination • You can combine these commands in a single

print function

Example:

print (“a”, “b”, “c”, sep = “**”, end = “$” )

print (“d”, “e”, “f”, sep = “-”, end = “” )

>> a**b**c$d-e-f

• The order does not matter

Tab Command • Another escape command is the tab command and

it is denoted by “ \t ”

• This must be added inside a string

Example:

print (“First”, “\t”, “Second”, “\t”, “Third”)

print (“10.9”, “\t”, “11.2”, “\t”, “11.4”)

>> First Second Third

10.9 11.2 11.4

String Concatenation • You cannot “add” strings together but we can

concatenate them with the addition operator

print (“Donald” + “Seok”)

>> DonaldSeok

print (“19” + “20”)

>> 1920

String Repetition • You can also “multiply” strings to print them

out repeatedly

Example:

lyrics = “Fa ” + “La ” * 8

Print (lyrics)

>> Fa La La La La La La La La

Formatting a String • Python also has a format( ) command

• This command allows you to format a string and returns it as a new piece of data

• This can be done in a variable or directly in the print function

Formatting a String • The format( ) function accepts two arguments

• The first argument is the piece of data you want to format (we will work with strings first)

• The second argument is the formatting pattern you would like it to follow

Formatting a String •One common pattern of formatting is to

ensure that a string has a known number of characters

• For example, let’s say you want your output to look like this:

Name Class

Donald Seok Computer Programming

Formatting a String Name Class

Donald Seok Computer Programming

• You’ll need the strings “Name” and “Donald Seok” to have the same number of characters in them so that the strings “Class” and “Computer Programming” will align perfectly after them

Formatting a String • Something to keep in mind: Python spaces

each character the same, regardless of actual character width

Example:

“hello”

“WQWQW”

“I I I”

- These all have the same string width in Python

Formatting a String •We can achieve this task by adding extra spaces to

either the beginning or the end of a string

Example:

x = format (“Name”, “<20s”)

• This generates a string with 20 characters, which means Python will add 16 spaces after the 4 characters in the word “Name”

• The “<“ character means left justify the string and place extra spaces at the “end” of the new string

Formatting a String • You guessed it … you can also tell Python to

right justify the string and add spaces to the beginning of the string

Example:

x = format (“Name”, “>20s”)

print (x)

>> Name

^ 16 blank characters

Formatting a String • So, let’s try making that output:

word_name = format (“Name”, “<20s”)

my_name = format(“Donald Seok”, “<20s”)

print ( word_name , “Class”)

print ( my_name , “Computer Programming”)

>> Name Class

Donald Seok Computer Programming

Formatting Numbers

•The format( ) command also works on numbers

•However, it is important to keep in mind that the number, whether integer or float, will be returned as a string from the function

Formatting Numbers

•This command would’ve come in handy when we were writing programs that printed out prices

•This is what we’re used to seeing:

a = 1 / 3

Print (a)

>> 0.3333333333333333

Formatting Numbers

•Now, using the format function:

a = 1 / 3

b = format ( a , “.2f” )

print (b)

>> 0.33

#The number denotes the number of characters you would like to remain after the decimal point

Formatting Patterns a = 100000 / 6

print ( format( a, “.3f” ) ) # 3 digits after “.”

>> 16666.666

print ( format( a, “,.3f” ) ) # 3 digits and commas

>> 16,666.666

print ( format( a, “>20,.3f” ) ) # 3 digits, commas and 20

>> 16,666.666characters, right justified

Formatting Percentages a = 0.52

print ( format( a, “ % ” ) ) # convert to percentage

>> 52.000000 % multiply by 100

print ( format( a, “ .2% ” ) ) # percentage with 2 digits

>> 52.00 %after decimal point

print ( format( a, “ .0% ” ) ) # percentage as integer

>> 52 %

Formatting Integer a = 20000

print ( format( a, “ ,d ” ) ) # add commas

>> 20,000

print ( format( a, “ >20, ” ) ) # add commas and 20

>> 20,000 characters, right justified

Programming Challenge

•Write a program that asks the user for three cars, three different interest rates, and three prices

•Print an output like this:

Car Name Interest Rate Price

BMW 3.0% $ 79,435.60

Mercedes Benz 4.2% $ 119,324.54

Bentley 6.5% $234,674.93