Here’s the updated code with the necessary corrections: library(shiny) ui <- fluidPage( titlePanel("Optimization Example"), sidebarLayout( sidebarPanel( # action buttons and sliders to modify parameters of optimization ), mainPanel( outputPanel( textOutput("result") ) ) ) ) server <- function(input, output) { eval_f <- reactive({ req(input$submit) obj <- input$obj return(list(object = rlang::eval_tidy(rlang::parse_expr(obj)))) }) eval_g_ineq <- reactive({ req(input$submit) ineq <- input$ineq grad <- lapply(unlist(strsplit(input$gineq, ",")), function(par) { val <- rlang::eval_tidy(rlang::parse_expr(as.character(par))) return(val) }) return(list(constraints = ineq, jacobian = as.

Understanding the Performance Issue with Outer Apply Why Does the Query Take a Long Time? When working with data queries, especially those involving joins and subqueries, performance can be a significant concern. In this article, we’ll delve into a specific problem that arises when using the Outer Apply operator in SQL Server, which is often referred to as the “outer apply takes a long time” issue. The problem presented involves a query with a Common Table Expression (CTE) and an Outer Apply clause.

Dictionary Replacement and Modification in a Pandas DataFrame In this article, we will explore how to create a new column in a Pandas DataFrame by mapping words from a dictionary to another column, replacing non-dictionary values with ‘O’, and modifying keys that are not preceded by ‘O’ to replace ‘B’ with ‘I’. Introduction The task at hand is to create a function that can take a dictionary as input and perform the following operations on a given DataFrame:

Understanding Top X Records without Overlap from Multiple Jobs =========================================================== In a scenario where multiple jobs process against the same table simultaneously, it’s essential to ensure that no overlap occurs in their queries. One way to achieve this is by selecting top X records without overlap, which can be achieved using Common Table Expressions (CTEs) and clever query design. Background: The Problem of Locks and Overlap When multiple jobs run the same query against a table, it’s likely that some degree of locking will occur.

Understanding the Facebook Feed Dialog with FBConnect SDK When working with the Facebook Connect SDK, it’s essential to understand how to successfully post content to a user’s feed. In this article, we’ll delve into the specifics of the Facebook Feed Dialog and explore the nuances of setting the picture and link parameters. Background on Facebook Connect SDK The Facebook Connect SDK is a library that enables developers to integrate Facebook functionality into their applications.

Introduction to ggplot2 and Color Mapping As a data visualization enthusiast, you’ve likely encountered the popular R package ggplot2 for creating stunning visualizations. One of its strengths lies in its ability to map variables to colors, making it an ideal choice for exploring categorical data. In this article, we’ll delve into the world of ggplot2 color mapping and explore a common challenge: generating a list of labels and colors for the legend.

Hibernate: A Deep Dive into Retrieving Last N Rows with Spring Boot JpaRepository As a developer, working with databases and retrieving specific data can be a daunting task. In this article, we’ll delve into the world of Hibernate and explore how to retrieve the last n rows from a database using Spring Boot’s JpaRepository. Introduction to Spring Data JPA and JpaRepository Spring Data JPA is an abstraction layer that simplifies interactions between Java applications and relational databases.

Understanding Rprof Output for Memory Usage Analysis ====================================================== Introduction Rprof is a valuable tool in R programming language for analyzing memory usage during function execution. It provides detailed information about peak memory usage, memory allocations, and other performance metrics. However, interpreting the output can be challenging, especially for those without prior experience with R or memory profiling. This article aims to provide a comprehensive guide on how to interpret the output produced by summaryRprof(), focusing on peak memory usage analysis.

Truncating Timestamps in SQL Server: A Step-by-Step Guide Overview of Timestamp Truncation Timestamp truncation is a common requirement in various applications, where the goal is to convert input timestamps into their corresponding top or bottom hour. For instance, taking a timestamp like 2020-02-12 06:56:00 and converting it to 2020-02-12 06:00:00, or taking another timestamp like 2020-02-12 07:14:00 and converting it to 2020-02-12 08:00:00. This process can be achieved using SQL Server’s built-in date functions.

Understanding the Issue with Detecting Touch on a UIButton in a UIScrollView In our latest project, we encountered an interesting issue where a UIButton within a UIScrollView was unable to detect touch events. This was a challenging problem that required some digging into the iOS framework and debugging techniques. The Problem: A Button Inside a UIScrollView The issue occurred when we added a UIButton as a child view of a UIView, which itself was contained within a UIScrollView.