Pandas create new column based on other columns. Task: We have a Da

Pandas create new column based on other columns. Task: We have a DataFrame containing event data and we want to create a new column called 'Discounted_Price'. It’s bit straight forward to create a new column with just a simple if-else condition but in this post we will focus on multiple if/elseif conditions that returns different values for each condition. This new column will be calculated by applying a 10% Oct 21, 2021 · In today’s short guide we discussed to add new columns in pandas DataFrames based on the values of existing columns. Operations are element-wise, no need to loop over rows. loc, . This line of code assigns a new column 'C' to the DataFrame 'df'. Each of these methods has a different use case that we explored throughout this post. map() and Pandas . I begin with setting an index in df2 and df that will match between the frames, however some of the index in df2 doesn't exist in df . Adding a new column to a DataFrame based on values from existing columns is a common operation in data manipulation and analysis. Feb 2, 2024 · Create New Columns in Pandas DataFrame Based on the Values of Other Columns Using the DataFrame. apply() method. You can use this method to create a new column based on a given condition. So basically, for each row the value in the new column should be the value from the budget column * 1 if the symbol in the currency column is a euro sign, and the value in the new column should be the value of the budget column * 0. Apr 23, 2025 · One common task is adding new columns based on calculations or changes made to the existing columns in a DataFrame. Related: Create new column based on values from other columns / apply a function of multiple columns, row-wise in Pandas (same idea, but the selection criteria are based on multiple columns) – wjandrea Jan 2, 2025 · Adding a new column to a DataFrame in Pandas is a simple and common operation when working with data in Python. There can be multiple methods, based on different requirement. Nov 11, 2024 · 2. apply() Method This tutorial will introduce how we can create new columns in Pandas DataFrame based on the values of other columns in the DataFrame by applying a function to each element of a column or using the DataFrame. Pandas Add Column Based on Existing Column . apply(). Oct 2, 2016 · The category is a column in df2 which contains around 700 rows and two other columns that will match with two columns in df. use NumPy's where(~) method for creating binary columns. Aug 9, 2021 · In this post, you learned a number of ways in which you can apply values to a dataframe column to create a Pandas conditional column, including using . In this article, we will be exploring different ways to do that. May 7, 2019 · Create a new column by assigning the output to the DataFrame with a new column name in between the []. Although this sounds straightforward, it can get a bit complicated if we try to do it using an if-else conditional. Jul 11, 2024 · We use assign() function in Pandas to assign new columns to a DataFrame. The apply() function allows us to apply a function to each row or column of a DataFrame and return a new DataFrame. Making a new column in pandas based Aug 10, 2023 · To create a new column based on other columns, either: use column-arithmetics for fastest performance. Once we have had our data into a pandas DataFrame, we can create a new column based on the value of another column using the apply() function. To add a new column based on an existing column in Pandas DataFrame use the df[] notation. Let's discuss how to add new columns to the existing DataFrame in Pandas. You can quickly create new columns by directly assigning values to them. The new column 'C' will have a value of 0 if the values in columns 'A' and 'B' are equal, a value of 1 if the value in column 'A' is greater than the value in column 'B', and a value of -1 if the value in column 'A' is less than the value in column 'B'. Feb 20, 2024 · Introduction. np. I would like to make a new column based on an if statement that has conditionals of two or more other columns in a dataframe. Jun 28, 2022 · In this post we will see how to create a new column based on values in other columns with multiple if/else-if conditions. 78125 if the symbol in the currency column is a dollar sign. Specifically, we showcased how to do so using apply() method and loc[] property in pandas, as well as using NumPy’s select() method in case you are interested into a more vectorised approach. This operation can enhance or adjust the original dataset for further analysis, visualization, or modeling. It returns a new DataFrame with the new columns added. This is a one line of code that achieves the desired result. use the apply(~) method, which is the slowest but offers the most flexibility Jun 19, 2023 · Step 2: Create a New Column Based on the Value of Another Column. Jul 16, 2022 · Photo by Pascal Müller on Unsplash What is this about? Having worked with SAS for 13 years, I was a bit puzzled that Pandas doesn’t seem to have a simple syntax to create a column based on Jul 1, 2020 · When we’re doing data analysis with Python, we might sometimes want to add a column to a pandas DataFrame based on the values in other columns of the DataFrame. Let's use the above DataFrame and modify the code to create a new column 'Category' based on the 'Event' column. We can use case_when method to create a new column using a switch statement. select(), Pandas . Thankfully, there’s a simple, great way to do this using numpy!. First, assign a column with the default value ('Other' in the example in the OP), and then replace values in this new column using a list of (condition, replacement value) tuples. We can derive a new column by computing arithmetic operations on existing columns and assign the result as a new column to DataFrame. Use rename with a dictionary or function to rename row labels or column names. haldyc zqti qshpiq zvlzwj eevn qbnziclud rdrhux ypqnb glo saoyld