Based on the provided code, it appears that you’re trying to find the nearest previous higher element in a vector of numbers. The approach you’ve taken so far is not efficient and will explode for large inputs. Here’s an optimized solution using Rcpp: cppFunction(' List pge(NumericVector rowid, NumericVector ask) { int n = rowid.size(); std::vector<int> stack; std::vector<NumericReal> prevHigherAsk(n, NA_REAL); std::vector<double> diff(n, 0.0); for(int i = 0; i < n; i++) { double currentAsk = ask[i]; while(!

Working with JSON Columns in PostgreSQL: A Deep Dive Introduction In recent years, JSON (JavaScript Object Notation) has become a popular data format for storing and exchanging structured data. Its flexibility and simplicity make it an attractive choice for many applications, including web development, data science, and business intelligence. However, working with JSON columns in PostgreSQL can be challenging, especially when it comes to updating existing values. In this article, we will explore the challenges of updating a JSON column using built-in operators and functions in PostgreSQL 9.

Creating a DataFrame for Each List of Lists Within a List of Lists of Lists In this article, we will explore how to create a pandas DataFrame for each list of lists within a list of lists of lists. We will also discuss different approaches to achieving this goal and provide examples to illustrate the concepts. Background A list of lists is a nested data structure where each inner list represents an element in the outer list.

Removing Points Which Deviate Too Much from Adjacent Point in Pandas Introduction Pandas is a powerful library used for data manipulation and analysis in Python. It provides data structures and functions to efficiently handle structured data, including tabular data such as spreadsheets and SQL tables. One common task in data analysis is removing outliers or noisy points from a dataset that deviate significantly from the surrounding points. In this article, we will explore how to remove points which deviate too much from adjacent point in Pandas using the rolling function and a simple yet effective approach.

Chaining in Pandas: A Guide to Simplifying Your Data Manipulation When working with pandas dataframes, chaining operations can be an effective way to simplify complex data manipulation tasks. However, it requires a good understanding of how the DataFrame’s state changes as you add new operations. The Problem with Original DataFrame Name df = df.assign(rank_int = pd.to_numeric(df['Rank'], errors='coerce').fillna(0)) In this example, df is assigned to itself after it has been modified. This means that the first operation (assign) changes the state of df, and the second operation (pd.

Converting Ensemble IDs to Gene Symbols in R Introduction The Ensembl database provides a comprehensive collection of genomic data, including gene symbols, for various species. However, when working with R, users often encounter the Ensemble ID, which is a unique identifier for each gene. In this article, we will explore how to convert Ensemble IDs to their corresponding gene symbols using R. Understanding Ensemble IDs and Gene Symbols Ensemble IDs are numerical identifiers assigned to genes in the Ensembl database.

Pandas Multiindex Re-indexing: A Step-by-Step Guide Introduction The Pandas library in Python is widely used for data manipulation and analysis. One of its powerful features is the ability to create multi-level indices, which allow for more efficient data storage and querying. In this article, we will explore how to re-index a DataFrame with a MultiIndex on both the index and columns using Pandas. Background When working with DataFrames in Pandas, it’s common to have multiple levels of indexing.

Querying Timestamps: Retrieving Values Before and After a Specific Date When working with timestamp data in SQL Server, it’s not uncommon to need to retrieve values that occur before or after a specific date. In this article, we’ll explore how to achieve this using various techniques, including CROSS JOIN, datediff(), and row_number(). We’ll also examine the provided Stack Overflow question and answer, which demonstrate an efficient approach without relying on Common Table Expressions (CTEs).

The problem lies in the fact that the covariance matrix V is not positive definite. This can be verified by computing the eigenvalues of V, which are all negative except for one, indicating that V does not meet the necessary condition for a multivariate normal distribution. To generate random numbers from a multivariate normal distribution with a non-positive definite covariance matrix, you have to decide whether to truncate components corresponding to negative eigenvalues (which is what mvtnorm::rmvnorm() does by default) or to throw an error.

Understanding XIB Files and Image References Xcode, a popular integrated development environment (IDE) for macOS and iOS app development, uses XIB files to design user interfaces. These XIB files contain Objective-C or Swift code that defines the layout of views, controls, and other UI elements in an app. In this post, we’ll explore how to identify which XIB file references a specific image. The Role of Image References in XIB Files When you add an image to a XIB file, it becomes referenced in the UIImage property of various UI elements, such as UIImageView, UIImageAsset, or even indirectly through other controls.