Pandas groupby unique count Several examples will explain how to group by and apply statistical functions like: sum, count, mean etc. groupyby (). Use the unique(), value_counts(), and nunique() methods on Series. Returned in order of appearance. core. This method returns the number of unique values in each group of the Groupby object. nunique() is also av You could sort the data at any point! Best performance would be to sort after the aggregation -> df. count () The basic approach to use this method is to assign the column names as parameters in the groupby () method and then using the count () with it. Import or create dataframe using DataFrame () function in which pass the data as a Feb 2, 2024 · df. Also, it seems that the groupby object already knows this information, so wouldn't I just be duplicating the effort? Aug 17, 2021 · In this short guide, we'll see how to use groupby () on several columns and count unique rows in Pandas. Returns: Series Unique values for each of the grouped values. groupby(): More flexible for aggregating multiple metrics (sum, mean, etc. If the groupby as_index is False then the returned DataFrame will have an additional column with the value_counts. Series: Jul 23, 2025 · Output: Method 2: Using pandas. Jul 23, 2025 · Prerequisites: Pandas In this article, we are finding and counting the unique values present in the group/column with Pandas. pandas. It returns unique values for each of the grouped values. The Notes If the groupby as_index is True then the returned Series will have a MultiIndex with one level per input column. nunique () function returns a series with the specified axis's total number of unique observations. groupby. Jul 23, 2025 · Here, we can count the unique values in Pandas groupby object using different methods. We can create a grouping of categories and apply a function to the categories. 3 days ago · Conclusion Finding unique value combinations and their counts is a foundational skill in data analysis. . Aug 29, 2021 · In this article, you can find the list of the available aggregation functions for groupby in Pandas: * count / nunique – non-null values / count number of unique values * min / max – minimum/maximum * first / last - return first or last value per group * unique - all unique values from the group * std – standard Jan 19, 2024 · This article explains how to get unique values and their counts in a column (= Series) of a DataFrame in pandas. For example, we have a data set of countries and the private code they use for private matters. groupby(). nunique() Method df. groupby (): This method is used to split the data into groups based on some criteria. This article depicts how the count of unique values of some attribute in a data frame can be retrieved using Pandas. Unique values are the distinct values that occur only once in the dataset or the first occurrences of duplicate values counted as unique values. org Sep 15, 2021 · Learn how to use Pandas to count unique values in a GroupBy object, allowing you to count distinct values using the popular groupby method. I'm thinking I just need to provide a function that returns the count of distinct items of a Series object to the aggregate function, but I don't have a lot of exposure to the various libraries at my disposal. Core Syntax: Utilizing Groupby and Nunique for Efficiency To effectively compute the unique count per group, Pandas employs a fluent, method-chaining syntax that is both highly optimized and exceptionally readable. Example 1: In this example, we separately count occurrences of all the columns present in a dataset. To count unique values in a pandas Groupby object, we need to use the nunique () method. Pandas offers two primary methods: value_counts(): Best for quick, simple counts of combinations. unique() Method When we are working with large data sets, sometimes we have to apply some function to a specific group of data. The total number of Count unique values using pandas groupby [duplicate] Asked 8 years, 10 months ago Modified 2 years, 11 months ago Viewed 392k times See full list on statology. Feb 1, 2016 · I have datafarme df: id name number 1 sam 76 2 sam 8 2 peter 8 4 jack 2 I would like to group by on 'id' column and count the number of unique values based on the pair of (name,number)? id To get all these distinct values, you can use unique or drop_duplicates, the slight difference between the two functions is that unique return a numpy. unique # SeriesGroupBy. Approach: Import the pandas library. Method 1: Count unique values using nunique () The Pandas dataframe. So to count the distinct in pandas aggregation we are going to use groupby () and agg () method. Hash table-based unique, therefore does NOT sort. sort_values() More context + options here: pandas groupby, then sort within groups @josepmaria Jul 23, 2025 · In this article, let's see how we can count distinct in pandas aggregation. Pandas objects can be split on any of their axes. SeriesGroupBy. ). The column is labelled ‘count’ or ‘proportion’, depending on the normalize parameter. array while drop_duplicates returns a pandas. We want to count the number of codes a country uses. Below are various examples that depict how to count occurrences in a column for different datasets. agg(). agg() Method df. Listed below are the different methods from Aug 3, 2023 · By counting the number of unique values in a Groupby object, we can gain insights into the diversity and distribution of the data within each group. unique() [source] # Return unique values for each group. Often there is a need to group by a column and then get sum() and count(). tcoxa pnk seew hikjn ouu sxiq goxl djdoym pnsu ywm dedylkut ickpt tttkvht wxbphq oqg