Formato de cadena#

Introducción#

The recommended way to format text and numbers in Python is with f-strings. They allow variables, expressions, and function calls to be embedded directly inside {}.

To create an f-string, add f before the string, and place any variable, expression, or function call inside {}.

x = 1
y = 5

# Display the variables using an f-string
controller.screen.print(f"Position: ({x}, {y})")


# Display a calculation with an f-string
controller.screen.print(f"Sum: {5 + 3}")


# Display the robot's battery capacity with an f-string
controller.screen.print(f"Battery: {controller.get_battery_level()}%")

f-strings – Incrusta variables y expresiones directamente en el texto.

  • f”{value}” – Displays variables, expressions, or function calls inside a string.

Formato de números en cadenas f: controle cómo aparecen los valores numéricos.

  • :.xf – Sets the number of decimal places to show.

  • round – Rounds a number to a given number of decimal places.

  • :, – Adds commas as thousands separators.

  • :.x% – Converts a decimal to a percentage with x decimal places.

  • :#x – Formats a number as hexadecimal.

  • :b – Formats a number as binary.

Combinación de cadenas: combina texto y valores.

  • f”{value}” – Combine strings and variables in a single expression.

  • + operator – Concatenate strings manually with optional type conversion.

Métodos de cadena: cambian el caso del texto.

  • upper – Converts all characters to uppercase.

  • lower – Converts all characters to lowercase.

Comprobaciones de subcadenas: prueba la presencia o posición del texto.

  • in – Checks if a word exists in a string.

  • startswith – Checks if a string begins with a given value.

  • endswith – Checks if a string ends with a given value.

Secuencias de escape: formatear la salida con caracteres especiales.

  • \n – Adds a line break (new line).

  • \t – Adds a tab space between items.

Formato de números en cadenas f#

Las cadenas f permiten un control preciso sobre los decimales, el redondeo, los separadores de miles y más mediante el uso de los siguientes especificadores de formato:

Fixed Decimal Places#

.xf controls how many decimal places a number is displayed with.

Usage:
.xf

Parámetros

Descripción

x

La cantidad de decimales a mostrar.

 
# Display pi with 2 decimal places
pi = 3.1415926535
controller.screen.print(f"Pi: {pi:.2f}")

# Output: Pi: 3.14

Rounding Numbers#

round rounds numbers outside of an f-string or inside of the {}.

Usage:
round(number, x)

Parámetros

Descripción

number

El número a redondear.

x

La cantidad de decimales a redondear.

 
# Display a value rounded to only 2 decimal places
value = 5.6789
controller.screen.print(f"{round(value, 2)}")

# Output: 5.68

Thousands Separator#

, inserts commas as thousands separators to make large numbers more readable.

Usage:
,

Parámetros

Descripción

Este especificador de formato no tiene parámetros.

 
# Display a large number separated with commas
number = 1234567
controller.screen.print(f"{number:,}")

# Output: 1,234,567

Percentage#

.x% formats decimal values as percentages.

Usage:
.x%

Parámetros

Descripción

x

La cantidad de decimales a mostrar.

 
# Display a converted decimal to a percentage
value = 0.875

controller.screen.print(f"{value:.1%}")

# Output: 87.5%

Hexadecimal#

.#x converts numbers to hexadecimal.

Usage:
.#x

Parámetros

Descripción

Este especificador de formato no tiene parámetros.

 
# Convert 255 to hexadecimal
number = 255

controller.screen.print(f"{number:#x}")

# Output: 0xff

Binary#

b converts numbers to binary (base 2).

Usage:
b

Parámetros

Descripción

Este especificador de formato no tiene parámetros.

 
# Convert 3 to binary
controller.screen.print(f"Binary: {3:b}")

# Output: Binary: 11

Combinando cadenas#

Puede combinar (o concatenar) cadenas utilizando dos enfoques:

Using f-strings#

With f-strings, you can embed variables directly inside {}.

# Display an answer based on the given emotion
emotion = "good"

controller.screen.print(f"I'm {emotion}, you?")

+ Operator#

You can combine strings manually using the + operator.

Note: Non-strings must first be converted to strings using str().

# Display the x and y values
x = 10
y = 20

controller.screen.print("X: " + str(x) + ", Y: " + str(y))

Métodos de cadena#

Python proporciona métodos integrados para modificar y comprobar cadenas.

upper#

upper converts all letters in a string to uppercase.

Usage:
upper()

Parámetros

Descripción

Este método no tiene parámetros.

 
# Display a message in uppercase
message = "vexcode"

controller.screen.print(message.upper())

# Output: VEXCODE

lower#

lower converts all letters in a string to lowercase.

Usage:
lower()

Parámetros

Descripción

Este método no tiene parámetros.

 
# Display a message in lowercase
message = "VEXCODE"

controller.screen.print(message.lower())

# Output: vexcode

Comprobación de subcadenas#

in#

in is a keyword that checks if a word exists in a string.

# Display a message if "Hey" is in the string
message = "Hey everyone!"

if "Hey" in message:
    controller.screen.print("Hello!")

startswith#

startswith returns if a string starts with a specific word. This method returns a Boolean value:

  • True - The word starts the string.

  • False - The word does not start the string.

Usage:
startswith(substring)

Parámetros

Descripción

substring

La subcadena a comprobar dentro de la cadena.

 
# Display a message if the string starts with "AIR"
message = "AIR Drone"

if message.startswith("AIR"):
    controller.screen.print("AIR first!")

endswith#

endswith returns if a string ends with a specific word. This method returns a Boolean value:

  • True - The word ends the string.

  • False - The word does not end the string.

Usage:
startswith(substring)

Parámetros

Descripción

substring

La subcadena a comprobar dentro de la cadena.

 
# Display a message if the string ends with "Drone"
message = "AIR Drone"

if message.endswith("Drone"):
    controller.screen.print("Drone last!")

Secuencias de escape#

Las secuencias de escape son caracteres especiales que se utilizan dentro de cadenas para dar formato a la salida de texto. Solo están disponibles para su uso con la Consola.

New Line#

\n moves text to a new line when printing.

# Display text on two lines
print("First line\nSecond line")

Tab Spacing#

\t inserts a tab space between words or numbers.

# Display the quantity of barrels
quantity = 2
print("IDs:\t", quantity)
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