Python Print

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1. Print

Ex1 Print Basic Interger and String

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str_name= "hello"
num_value= 999
print(f"str value is {str_name}, and number is {num_value}")

output:

str value is hello, and number is 999

%-formatting-OLD

Example 1 Print String with % Operator

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text = 'world'
print("hello " + text)
print('hello %s' % text)

name = "Test"
num = 100
print("Hello, %s. My num is  %s." % (name, num))

output:

hello world
hello world
Hello, Test. You are 100.

3. str.format()- NEW

str.format() 是對 %-formatting 的改進，可以用函式呼叫語法，可以通過 format() 方法對被轉換為字串的物件

ex1: Print Basic String

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text = 'world'
year = 2022
print('hello {} {}'.format(text, year))
# hello world 2022

ex2 print dict字典 with **

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person = {'name': 'Eric', 'age': 74}
print ("Hello, {name}. You are {age}.".format(name=person['name'], age=person['age']))
print ("Hello, {name}. You are {age}.".format(**person))

output

Hello, Eric. You are 74.

ex3: print X decimal places

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float = 2.154327
format_float = "{:.2f}".format(float)
print(format_float)

output:

2.15

ex4: print decimal format

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number = 1.345
f = '{0:.2g}'.format(number)
print(f)
f = '{0:.3g}'.format(number)
print(f)
f = '{0:.4g}'.format(number)
print(f)

output:

1.3
1.34
1.345

Ex5: 轉16進位

print('{:x}'.format(23))
output:

17

4 printf - New

Ex1 Print Basic String

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text = 'world'
num = 9000
print(f'Hello , {text}')
print( f"{5 * 5 }")

output:

Hello world
25

Ex2 Print Basic Integer

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x = 10
y = 27
print(f'x + y = {x + y}')
# 37

Ex3 Print X decimal places

  • print 2 decimal places

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    now_value=123.456
    print(f'{now_value:.2f}')

    output:

    123.46

  • Comma between number, and print 2 decimal places

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    number=1000000
    print(f'The number, 1000000, format with a comma {number:,.2f}')

    output:

    The number, 1000000, format with a comma 1,000,000.00

Ex4 Date and Time

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from datetime import datetime
now = datetime.utcnow()
print(f"{now}") # 2022-07-30 09:21:30.500456
print(f"{now=:%y-%m-%d}") # now=22-07-30

Ex5 Runtime time

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import time

# starting time
start = time.time()
#script
for i in range(1,5):
    print(i)
#end time 
end = time.time()

#calculate run time
runtime =end - start

#you can use either method:
print(" Runtime of the program is {runtime:%.8f}")
print(f"Runtime of the program is {runtime:.8f}")
print(f"Runtime of the program is {(end - start):.8f}")
print("%.8f" % runtime)

5 other print function

Ex1: round number:

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number = 1.345
print(round(number))
# 1

Ex2: tab

print(('===\t=========== \t =========== \t =========== \n').expandtabs(8))

output:
=== =========== =========== ===========

Ex3: lower String

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name = "Ja Laaaa"
print (f"{name.lower()} is funny.")

output:

　ja laaaa is funny.

6 Print List

There are couple of ways to print list

test = ['A' , 'B', 'C' , 'D']

  • Method 1: using for loop
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    for i in test:
        print(i,end=' ') 
    print()
    # A B C D
  • Method 2: *listname unpack list
    We can use without for loop to unpack list

    print(*test) # A B C D

Print new line:

print(*test, sep=’\n’)