Introduction

The problem of not seeing any results from profvis is a common issue that can be frustrating when trying to profile the performance of R code. In this article, we will delve into the world of profiling and explore what could be causing this issue.

What is Profiling?

Profiling is a process used to measure the execution time and behavior of computer programs. It helps developers understand how their code is executing, identify bottlenecks, and optimize performance. Profiling tools provide insights into various aspects of program execution, such as CPU usage, memory allocation, and function calls.

What is profvis?

profvis is a profiling tool developed by the R Community. It provides an interactive interface for exploring the performance of R code. The profvis package uses the Chrome DevTools protocol to collect data about the execution of your code, including call stacks, timing information, and memory usage.

Understanding Profiling in R

Before we dive into solving the issue with profvis, let’s first understand how profiling works in R.

Creating a Profiler

To start profiling, you need to create a profiler using the profvis function. This function returns an object that contains the profiling data.

library(profvis)
profvis({
  # Your code here
})

Collecting Profiling Data

The profvis function collects profiling data while your code executes. The collected data is stored in a list, which can be analyzed later using various functions provided by the profvis package.

Common Issues with profvis

Now that we have an understanding of how profiling works and creating a profiler, let’s explore some common issues that may cause profvis not to show any results.

1. Incorrect Usage

The most common issue is using profvis incorrectly. To fix this, make sure you are calling the function correctly and passing it your code as an argument.

library(profvis)
profvis({
  # Your code here
})

2. Insufficient Profiling Data

If profvis does not show any results, there might be insufficient profiling data collected. This can happen if the code execution is too short or if the profiling tool is not collecting data at the right time.

To fix this, increase the sampling rate or collect more data by analyzing the call stack and timing information.

3. Profiling Not Triggered

Sometimes, profvis might not be triggered correctly due to various reasons such as incorrect variable names, out-of-scope variables, or missing code blocks.

To fix this, ensure that your code is structured correctly, and all necessary variables are in scope.

Solving the Problem

Now that we have explored some common issues with profvis, let’s go back to the original problem and analyze it again.

The problem statement is:

“I’ve reading and I’ve been introduced to <code>profvis</code> package. The thing is that it works in excercise but not with my real code.”

Upon analyzing the provided code, we notice that there are a few potential issues:

1. Incorrect Variable Name

In the testaaa function, the variable name s.marca and s.producto are used without defining them anywhere.

To fix this, define these variables before using them.

s.marca <- html_nodes(node,"div.marca a") %>% html_text
s.producto <- html_nodes(node,"div.detalle a") %>% html_attr("href")

2. Incorrect Data Structure

The testaaa function returns a list of data frames, but the profvis function expects a single data frame.

To fix this, combine the data frames into one using bind_rows.

falabella_data_list <- lapply(doc, product_info) %>% bind_rows()

3. Missing Code Blocks

The testaaa function is missing some code blocks that are required for profiling.

To fix this, add the necessary code blocks to collect data about the execution of your code.

profvis({
library("profvis")
library(RSelenium)
library(rvest)
library(dplyr)
library(stringr)
library(urltools)

#start RSelenium

rD  <- rsDriver(port = 4506L, browser = "firefox", version = "latest",
                geckover = "latest", iedrver = NULL, phantomver = "2.1.1",
                verbose = TRUE, check = TRUE)

remDr <- rD[["client"]]

### URLS ###

falabella_urls <- c("http://www.falabella.com.pe/falabella-pe/category/cat7230497/Accesorios-Hombre?No=0&amp;Nrpp=1000",
                    "http://www.falabella.com.pe/falabella-pe/category/cat7230497/Accesorios-Hombre?No=1000&amp;Nrpp=1000")

#############################

testaaa <- function() {

falabella_data_list <- list()

for (i in falabella_urls$url[1:2]) {

  remDr$navigate(i)

  print(i)

  Sys.sleep(05)

  page_source <- remDr$getPageSource()

  product_info <- function(node){

    subcategoria_url <- str_split(path(i), "/\\")[[1]][4]
    s.marca <- html_nodes(node,"div.marca a") %>% html_text
    s.producto <- html_nodes(node,"div.detalle a") %>% html_attr("href")
    s.precio.antes <- html_nodes(node, "div.precio2 span") %>% html_text
    s.precio.actual <- html_nodes(node, "div.precio1 span") %>% html_text

    data.frame(
      fecha = as.character(Sys.Date()),
      subcategoria = subcategoria_url,
      ecommerce = "Falabella",
      marca = s.marca,
      producto = s.producto,
      precio.antes = ifelse(length(s.precio.antes) == 0, NA, s.precio.antes),
      precio.actual = ifelse(length(s.precio.actual) == 0, NA, s.precio.actual),
      stringsAsFactors=F
    )

  }

  doc <- read_html(iconv(page_source[[1]]), to="UTF-8") %>% 
    html_nodes(".cajaLP4x")

  productos <- lapply(doc, product_info) %>% bind_rows()

  falabella_data_list[[i]] <- products # add it to your list

}

falabella <- do.call(rbind, falabella_data_list)

profvis({
testaaa()
})

}

Conclusion

By analyzing the original problem and exploring common issues with profvis, we were able to identify and fix the problems in the provided code. With these changes, the profvis function should now work correctly and show profiling data for your R code.

Remember that profiling is an essential tool for understanding how your code is executing and identifying bottlenecks. By using profvis and following best practices, you can optimize the performance of your code and make it more efficient.

Last modified on 2024-11-27