Traversing Hierarchical Data with Oracle’s CONNECT BY Clause Oracle’s CONNECT BY clause is a powerful tool for querying hierarchical data. It allows you to traverse a tree-like structure, starting from the root and moving down to the leaf nodes. In this article, we’ll explore how to use CONNECT BY to filter rows that match a condition without breaking the hierarchy. Understanding Hierarchical Data Before diving into the query, let’s understand what hierarchical data is.

Checking for Non-Numeric Values in a Pandas DataFrame In this article, we will explore how to check if every value in a column of a pandas DataFrame is numeric and print the index of the cells that contain non-numeric values. Understanding the Problem Suppose you have a DataFrame with a mixture of integer and float values in one of its columns. You want to write a loop through this column to check if all values are numeric.

Finding Missing Observations within a Time Series and Filling with NAs Introduction Time series analysis is a powerful tool for understanding patterns and trends in data. However, real-world time series often contain gaps or missing observations, which can be problematic for certain types of analysis. In this article, we will discuss how to find missing observations within a time series and fill them with NAs (Not Available) using R. Understanding the Problem The problem described is as follows: you have a time series containing daily observations over a period of 10 years, but some rows are missing entirely.

Creating Dummy Data for a Database with Docker In this article, we will explore the process of creating dummy data for a database when using Docker. We will cover how to populate a Postgres database with sample data when running a Django application in a Docker container. Understanding Docker Compose and Volumes Docker Compose is a tool that allows us to define and run multi-container Docker applications. When we use Docker Compose, we can specify volumes to share files between the host machine and the container.

Updating a Date Column Using an Interval from Data in a Join Table In this article, we’ll explore how to update a date column in one table based on data in another table using a join. We’ll use PostgreSQL as our database management system and discuss the process of updating a new_date column by adding months to a date column from a separate table called plans. Understanding the Problem The problem at hand involves two tables: users and plans.

Here are a few suggestions to improve your approach: Looping the NLS Model: You can create an anonymous function within lapply like this: output_list <- lapply(mod_list, function(x) { fm <- nls(mass_remaining ~ two_pool(m1,k1,cdi_mean,days_between,m2,k2), data = x) coef(fm) }) This approach will return a list of coefficients for each model. 2. **Saving Coefficients as DataFrames:** You can use `as.data.frame` in combination with `lapply` to achieve this: ```r output_list <- lapply(mod_list, function(x) { fm <- nls(mass_remaining ~ two_pool(m1,k1,cdi_mean,days_between,m2,k2), data = x) as.

Converting Time in Factor Format into Timestamp In this article, we will explore how to convert time in factor format into a timestamp that can be plotted against. We’ll delve into the technical details of this process and provide examples to illustrate the steps involved. Understanding Factor Format When working with time data, R’s factor function is often used to represent time intervals. A factor in R is a discrete value that belongs to a specific set or class.

Handling Unpredictable JSON Keys with Python and Jinja When working with data that has arbitrary and unpredictable keys, extracting specific values can be a challenge. In this post, we’ll explore how to use Python and Jinja templating in dbt to extract desired values from JSON-like data. Introduction to the Problem The problem at hand is that the JSON blob column in our Redshift table contains data with arbitrary top-level keys. The structure of each JSON object is consistent within itself, but the top-level keys are different across objects.

Working with Multiple Keys in JSON and Returning Only Rows with Values in PostgreSQL 9.5 As a technical blogger, I’ve come across many queries where dealing with JSON data has proven challenging. In this article, we’ll explore how to find multiple keys in multiple JSON rows and return only those rows that have some value for specific keys. Introduction JSON (JavaScript Object Notation) is a popular data interchange format used extensively in modern applications.

Accumulative Multiplication Between Two Columns In this article, we will explore the concept of accumulative multiplication between two columns in a pandas DataFrame using Python. Background When working with financial data, it is common to calculate cumulative products or multiplications between consecutive values. This can be useful for calculating daily returns, risk metrics, or other performance indicators. One example that illustrates this concept is calculating the cumulative product of percentage changes and corresponding column values in a pandas DataFrame.