Formaterad stränglitreral

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Maria Eugenia Inzaugarat

Data Scientist

f-strängar

  • Minimal syntax
  • Lägg till prefixet f före strängen

way = "code"
method = "learning Python faster"
print(f"Practicing how to {way} is the best method for {method}")
Practicing how to code is the best method for learning Python faster
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Typkonvertering

  • Tillåtna konverteringar:
    • !s (strängversion)
    • !r (sträng med utskrivbar representation, dvs. med citattecken)
    • !a (som !r men escapar icke-ASCII-tecken)

 

name = "Python"

print(f"Python is called {name!r} due to a comedy series")
Python is called 'Python' due to a comedy series
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Formatspecificerare

  • Standardformatspecificerare:
    • e (vetenskaplig notation, t.ex. 5 10^3)
    • d (heltal, t.ex. 4)
    • f (flyttal, t.ex. 4.5353)

 

number = 90.41890417471841

print(f"In the last 2 years, {number:.2f}% of the data was produced worldwide!")
In the last 2 years, 90.42% of the data was produced worldwide!
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Formatspecificerare

 

  • datetime

 

from datetime import datetime
my_today = datetime.now()
print(f"Today's date is {my_today:%B %d, %Y}")
Today's date is April 14, 2019
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Indexuppslag

family = {"dad": "John", "siblings": "Peter"}
print("Is your dad called {family[dad]}?".format(family=family))
Is your dad called John?

 

  • Använd citattecken vid indexuppslag: family["dad"]
print(f"Is your dad called {family[dad]}?")
NameError: name 'dad' is not defined
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Escape-sekvenser

  • Escape-sekvenser: bakstreck \
print("My dad is called "John"")
SyntaxError: invalid syntax

 

my_string = "My dad is called \"John\""
My dad is called "John"
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Escape-sekvenser

family = {"dad": "John", "siblings": "Peter"}
  • Bakstreck är inte tillåtna i f-strängar
print(f"Is your dad called {family[\"dad\"]}?")
SyntaxError: f-string expression part cannot include a backslash

 

print(f"Is your dad called {family['dad']}?")
Is your dad called John?
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Inbyggda operationer

  • Fördel: beräkna uttryck och anropa funktioner direkt i strängen
my_number = 4
my_multiplier = 7
print(f'{my_number} multiplied by {my_multiplier} is {my_number * my_multiplier}')
4 multiplied by 7 is 28
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Anropa funktioner

def my_function(a, b):
  return a + b
print(f"If you sum up 10 and 20 the result is {my_function(10, 20)}")
If you sum up 10 and 20 the result is 30
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Reguljära uttryck i Python

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