SQL - COUNT() as Window Function
• COUNT() as a window function calculates running totals and relative frequencies without collapsing rows, unlike its aggregate counterpart which groups results into single rows per partition
Read more →Count
SQL - COUNT() Function with Examples
The COUNT() function is one of SQL’s five core aggregate functions, and arguably the one you’ll use most frequently. It returns the number of rows that match a specified condition, making it…
SQL - Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
Aggregate functions are the workhorses of SQL reporting. They take multiple rows of data and collapse them into single summary values. Without them, you’d be pulling raw data into application code…
Read more →R stringr - str_count() - Count Matches
The str_count() function from the stringr package does exactly what its name suggests: it counts the number of times a pattern appears in a string. Unlike str_detect() which returns a boolean, or…
R dplyr - count() and tally()
The dplyr package provides two complementary functions for counting observations: count() and tally(). While both produce frequency counts, they differ in their workflow position. count()…
Python - Count Occurrences in List
The count() method is the most straightforward approach for counting occurrences of a single element in a list. It returns the number of times a specified value appears.
Python - Count Occurrences in String
The count() method is the most straightforward approach for counting non-overlapping occurrences of a substring. It’s a string method that returns an integer representing how many times the…
PySpark - GroupBy and Count
GroupBy operations are the backbone of data aggregation in distributed computing. While pandas users will find PySpark’s groupBy() syntax familiar, the underlying execution model is entirely…
PySpark - Count Distinct Values
Counting distinct values is a fundamental operation in data analysis, whether you’re calculating unique customer counts, identifying the number of distinct products sold, or measuring unique daily…
Read more →Pandas - Get Row Count of DataFrame
• Use len(df) for the fastest row count performance—it directly accesses the underlying index length without iteration
Pandas - GroupBy and Count
• GroupBy operations in Pandas enable efficient data aggregation by splitting data into groups based on categorical variables, applying functions, and combining results into a structured output
Read more →Pandas - Count NaN/NULL Values in Column
• Pandas provides multiple methods to count NaN values including isna(), isnull(), and value_counts(dropna=False), each suited for different use cases and performance requirements.
How to Use COUNT in MySQL
COUNT is MySQL’s workhorse for answering ‘how many?’ questions about your data. Whether you’re building analytics dashboards, generating reports, or validating data quality, COUNT gives you the…
Read more →How to GroupBy and Count in Pandas
Counting things is the foundation of data analysis. Before you build models or create visualizations, you need to understand what’s in your data: How many orders per customer? How many defects per…
Read more →How to Create a Count Plot in Seaborn
Count plots are specialized bar charts that display the frequency of categorical variables in your dataset. Unlike standard bar plots that require pre-aggregated data, count plots automatically…
Read more →Count of Subset Sum: Number of Subsets with Given Sum
Given an array of non-negative integers and a target sum, count the number of subsets whose elements add up to exactly that target. This problem appears constantly in resource allocation, budget…
Read more →