> For the complete documentation index, see [llms.txt](https://developers.oxylabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.oxylabs.io/products/es/web-scraper-api/features/custom-parser/writing-instructions-manually/list-of-functions/function-examples.md).
# Ejemplos de funciones de análisis
Ejemplos prácticos de funciones de Custom Parser para procesamiento HTML, manipulación de cadenas, operaciones matemáticas y tareas comunes de análisis.
## Procesamiento de HTML
### `element_text`
#### HTML de ejemplo
```html
Este es un buen producto
12 3
```
**Extraer texto de un elemento HTML y eliminar espacios en blanco**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//*[@id='product-price']"]
},
{
"_fn": "element_text"
}
]
}
}
```
```json
{
"price": "12 3"
}
```
**Dado un valor de cadena como entrada, no hacer nada**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//*[@id='product-price']/text()"]
},
{
"_fn": "element_text"
}
]
}
}
```
```json
{
"price": " 12 3\n\n\n "
}
```
### `xpath`
#### HTML de ejemplo
```html
```
**Obtener todos los elementos de descripción**
```json
{
"description_items": {
"_fns": [
{
"_fn": "xpath",
"_args": ["//li[@class='description-item']/text()"]
}
]
}
}
```
```json
{
"description_items": ["Muy", "Bonito", "Calcetines"]
}
```
**Obtener el primer elemento de descripción**
```json
{
"first_description_item": {
"_fns": [
{
"_fn": "xpath",
"_args": ["(//li[@class='description-item'])[1]/text()"]
}
]
}
}
```
```json
{
"first_description_item": [
"Muy"
]
}
```
**Verificar si existe el elemento de la sección de descripción**
```json
{
"description_section_exists": {
"_fns": [
{
"_fn": "xpath",
"_args": ["boolean(//div[@class='description'])"]
}
]
}
}
```
```json
{
"description_section_exists": true
}
```
**Obtener el precio como número**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath",
"_args": ["number(//div[@class='price'])"]
}
]
}
}
```
```json
{
"description_section_exists": 123.12
}
```
**Múltiples expresiones a las que recurrir en caso de que falle la expresión anterior**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath",
"_args": [
"//div[@class='product-price']/text()", <--- esto no encuentra nada
"//div[@class='price']/text()" <--- esto encuentra el precio objetivo
]
}
]
}
}
```
```json
{
"price": [
"123.12"
]
}
```
**XPath `|` operador para hacer coincidir múltiples expresiones**
```json
{
"price_and_title": {
"_fns": [
{
"_fn": "xpath",
"_args": ["//div[@class='price']/text() | //div[@class='title']/text()"]
}
]
}
}
```
```json
{
"price_and_title": [
"Calcetines",
"123.12"
]
}
```
### `xpath_one`
#### HTML de ejemplo
```html
```
**Devuelve la primera coincidencia**
```json
{
"first_description_item": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//li/text()"]
}
]
}
}
```
```json
{
"first_description_item": "Muy"
}
```
**Usando funciones XSLT**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath_one",
"_args": ["number(.//div[@class='price'])"]
}
]
}
}
```
```json
{
"price": 123.12
}
```
## Manipulación de cadenas
### `amount_from_string`
#### HTML de ejemplo
```html
Calcetines
El precio es: 123.12 pesos
```
**Extraer cantidad de una cadena**
```json
{
"price": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//div[@class='price']/text()"]
},
{
"_fn": "amount_from_string"
}
]
}
}
```
```json
{
"price": 123.12
}
```
### `amount_range_from_string`
#### HTML de ejemplo
```html
El precio es: 123.12 pesos;
El precio es: 345.12 pesos;
El precio es: 678.12 pesos
```
**Extraer todas las cantidades de una cadena**
```json
{
"prices": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//div[@class='price']/text()"]
},
{
"_fn": "amount_range_from_string"
}
]
}
}
```
```json
{
"prices": [
123.12,
345.12,
678.12
]
}
```
### `join`
#### HTML de ejemplo
```html
El precio es: 123.12 pesos;
El precio es: 345.12 pesos;
El precio es: 678.12 pesos
```
**Unir un array de cadenas en una sola cadena**
```json
{
"price_variants": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//div[@class='price']"]
},
{ // Si llamamos a normalize-space() en la primera función de la canalización,
// devolverá solo el primer valor.
"_fn": "xpath",
"_args": ["normalize-space(text())"]
},
{
"_fn": "join",
"_args": ""
}
]
}
}
```
```json
{
"price_variants": "El precio es: 123.12 pesos;El precio es: 345.12 pesos;El precio es: 678.12 pesos"
}
```
### `regex_find_all`
#### HTML de ejemplo
```html
[una descripción]
[dos descripciones]
[tres descripciones]
```
**Encontrar todas las coincidencias entre dos caracteres**
```json
{
"descriptions": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//div[@class='description']/text()"]
},
{
"_fn": "regex_find_all",
"_args": ["\\[(.*)\\]"]
}
]
}
}
```
```json
{
"descriptions": [
"una descripción",
"dos descripciones",
"tres descripciones"
]
}
```
### `regex_search`
#### HTML de ejemplo
```html
[una descripción]
[dos descripciones]
[tres descripciones]
{la que necesito}
```
**Devolver la descripción entre dos caracteres**
```json
{
"description": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//div[@class='description']/text()"]
},
{
"_fn": "regex_search",
"_args": ["{(.*)}", 1]
}
]
}
}
```
```json
{
"description": "la que necesito"
}
```
### `regex_substring`
#### HTML de ejemplo
```html
* una descripción
* dos descripciones
* tres descripciones
* {esta que me gustaría reemplazar}
```
**Reemplazar una parte del texto con el valor especificado**
```json
{
"descriptions": {
"_fns": [
{
"_fn": "xpath_one",
"_args": [".//div[@class='description']/text()"]
},
{
"_fn": "regex_substring",
"_args": ["{this one i would like to get replaced}", "four description"]
},
{
"_fn": "regex_find_all",
"_args": ["\\*\\s(.*)\n"]
}
]
}
}
```
```json
{
"descriptions": [
"una descripción",
"dos descripciones",
"tres descripciones",
"cuatro descripciones"
]
}
```
## Funciones comunes
### `convert_to_*`
#### HTML de ejemplo
```html
```
**Obtener el conteo de variantes de precio**
```json
{
"price_variants": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//div[@class='price']"]
},
{
"_fn": "length"
}
]
}
}
```
```json
{
"price_variants": 5
}
```
**Obtener el conteo de variantes de precio en un array multidimensional**
HTML de ejemplo:
```html
```
```json
{
"number_of_variants": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//property"]
},
{
"_fn": "xpath",
"_args": [".//option"]
},
{
"_fn": "length"
}
]
}
}
```
```json
{
"number_of_variants": [
3,
3
]
}
```
### `select_nth`
#### HTML de ejemplo
```html
```
**Seleccionar el primer elemento de descripción del array**
```json
{
"price_and_title": {
"_fns": [
{
"_fn": "xpath",
"_args": ["//li[@class='description-item']/text()"]
},
{
"_fn": "select_nth",
"_args": 0
}
]
}
}
```
```json
{
"price_and_title": "Muy"
}
```
**Seleccionar el último elemento de descripción del array**
```json
{
"description_item": {
"_fns": [
{
"_fn": "xpath",
"_args": ["//li[@class='description-item']/text()"]
},
{
"_fn": "select_nth",
"_args": -1
}
]
}
}
```
```json
{
"description_item": "Calcetines"
}
```
## Funciones matemáticas
### `average`
#### HTML de ejemplo
```html
```
**Encontrar el promedio de todos los precios listados**
```json
{
"price_average": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//div[@class='price']"]
},
{
"_fn": "xpath_one",
"_args": ["number(text())"]
},
{
"_fn": "average"
}
]
}
}
```
```json
{
"price_average": 244.8
}
```
### `max`
#### HTML de ejemplo
```html
```
**Encontrar el máximo de todos los precios listados**
```json
{
"price_max": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//div[@class='price']"]
},
{
"_fn": "xpath_one",
"_args": ["number(text())"]
},
{
"_fn": "max"
}
]
}
}
```
```json
{
"price_max": 456.0
}
```
### `min`
#### HTML de ejemplo
```html
```
**Encontrar el promedio de todos los precios listados**
```json
{
"price_min": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//div[@class='price']"]
},
{
"_fn": "xpath_one",
"_args": ["number(text())"]
},
{
"_fn": "min"
}
]
}
}
```
```json
{
"price_min": 100.0
}
```
### `product`
#### HTML de ejemplo
```html
```
**Obtener el conteo de diferentes variantes de producto**
```json
{
"number_of_variants": {
"_fns": [
{
"_fn": "xpath",
"_args": [".//property"]
},
{
"_fn": "xpath",
"_args": [".//option"]
},
{
"_fn": "length"
},
{
"_fn": "product"
}
]
}
}
```
```json
{
"number_of_variants": 12
}
```
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