Apply function to multiple data frames r. For those of you familiar with ‘for’ loops, th.
Apply function to multiple data frames r. packages("dplyr") What is tibble?. Feb 19, 2024 · From the functions page we learned scant definitions of functional programming and functions. Aug 13, 2014 · I'm having an issue using apply functions (which I assume is the right way to do the following) across multiple data frames. margins set to 1. call(rbind, dfs), but the output will contain all columns that appear in any of the inputs. I want to create a new column (cold) by applying a calculation to a column (colc) for each data frame in a list of data frames. See vignette ("colwise") for more details. Aug 16, 2016 · A blog about statistics including research methods, with a focus on data analysis using R and psychology. com/apply-uni R code of this video: more Oct 28, 2016 · And I want to apply a function (in this case t. frames Asked 12 years, 8 months ago Modified 12 years, 1 month ago Viewed 562 times Apply unique Function to Multiple Columns in R (2 Examples) On this page you’ll learn how to retain only data frame rows that are unique in certain variables in the R programming language. A for-loop could work but I'm not sure how to set it up properly to call data frames. df1 <- data. Mar 26, 2018 · Using the purrr package to iterate over lots of values and return a data frame. Dec 7, 2021 · The mapply() function in R can be used to apply a function to multiple list or vector arguments. com offers daily e-mail updates about R news and tutorials about learning R and many other topics. list, shooter_cleaning) And then labeled each of the resulting data frames in the list according to Jul 10, 2019 · The function is to be applied for multiple data frames with different variable names and different na_values which is why I have written it in the first place, and it works fine, but I would like to simplify even more. Jul 23, 2025 · In this article, we will learn how to apply a function (or functions) across multiple columns in R using the dplyr package. cleaned <- lapply (data. Feb 21, 2017 · I have used lapply to apply a function to a number of data frames: data. The problem is that I o Mar 8, 2022 · Here I show you a useful family of functions that allows you to repetitively perform a specified function (e. Usage ddply( . How to do this in R? For Sep 11, 2024 · Introduction R is a powerful programming language primarily used for statistical computing and data analysis. Mar 8, 2022 · Today I’m going to talk about a useful family of functions that allows you to repetitively perform a specified function (e. To apply a function for each row, use adply with . Standard lapply or sapply functions work very nice for this but operate only on single function. Nov 27, 2019 · Looping through the list Once the data are split into separate data. The basic syntax for the apply () function is as follows: apply (X, MARGIN, FUN) X is the name of the Oct 9, 2013 · What I want to do is apply a function to the data frame BUT to subsets of the data. Basically I have multiple data frames and I simply want to run the same function across all of them. While there is a ready-made function The apply function takes data frames as input and can be applied by the rows or by the columns of a data frame. com Sep 15, 2025 · Learn how to use the apply () function in R to efficiently perform row-wise operations on matrices and data frames. Description For each subset of a data frame, apply function then combine results into a data frame. This can involve selecting rows where a certain column meets certain conditions (e. Aug 16, 2022 · This tutorial explains how to use the tapply() function in R, including several examples. y is a one row tibble with no column, consistently with group_keys(). What is transformation? Mar 31, 2023 · In this tutorial we show the use of apply in R, its variants, and a few of its relatives, applied to different data structures. It provides a set of functions for filtering, grouping, and transforming data. This is similar to do. frame and then use the data. Here's my current code: The key, a tibble with exactly one row and columns for each grouping variable, exposed as . For Feb 19, 2024 · From the functions page we learned scant definitions of functional programming and functions. fun = NULL, , . A <- as. progress = "none", . Whether you’re cleaning data, performing calculations, or transforming values, understanding row iteration techniques will significantly enhance your data manipulation capabilities. Syntax: lambda arguments: expression An anonymous function which we can pass in instantly without defining a name or any thing like a full traditional function. While extremely useful in certain cases, for loops can often be inefficient compared […] Apr 10, 2024 · How to filter the data frame by multiple conditions in R? You can use df[] notation and which() function to filter the data frame based on multiple conditions. Sometimes it is necessary to do calculations by a condition. For each row in the dataframe, I want to call a function on the row, and the input of the function is using multiple columns from that row. Split data frame, apply function, and return results in a data frame. Click here if you're looking to post or find an R/data-science job. Let's take an example for a better understanding. First, I’ll show how to use the apply function by row: Apply a function along an axis of the DataFrame. In R, they provide a flexible way to iterate through data frames and perform repetitive operations on their rows and columns. For example, if I want to fit a linear model of var1 vs var2 for each group I might do the looping with purrr::map () or lapply (). test()) across each "cell" of N dataframes so that what returns is a separate dataframe that contains a t value for each cell test performed. Oct 3, 2018 · Map a function to multiple data frames Asked 6 years, 10 months ago Modified 6 years, 10 months ago Viewed 2k times A list in R, however, comprises of elements, vectors, data frames, variables, or lists that may belong to different data types. Bind any number of data frames by row, making a longer result. The package can be downloaded and installed into the working space using the following command : install. Instead of writing repetitive code, you can use do. Apply Function to Each Cell of Data Frame in R (2 Examples) In this article you’ll learn how to apply a user-defined function to each data frame element in the R programming language. I generalized the function to take a second and third argument, and used that as the input for a grep() to change names of specific columns within all of my data frames. This function uses the following basic syntax: Oct 3, 2018 · Map a function to multiple data frames Asked 6 years, 10 months ago Modified 6 years, 10 months ago Viewed 2k times Jul 10, 2019 · The function is to be applied for multiple data frames with different variable names and different na_values which is why I have written it in the first place, and it works fine, but I would like to simplify even more. Jul 23, 2025 · Working with multiple data frames in R can often require repetitive tasks. frame, before I create the tree. I tried to pass the object How to apply the unique function to multiple columns in the R programming language. I need to apply a set of commands in R to all the individual . Depending on the specific data structure and desired operation, one of these alternative functions may be more appropriate. I'd like apply the same functions on each, without having to brute force them, or concatenate the dfs. Using a list like you tried previously might be a good option. each data frame) a name: e. Dec 31, 2012 · I'm thankful Reduce is in the language, but I really wish it were more like the *apply functions, letting you give it additional arguments for the functional supplied. Filtering a data frame typically refers to the process of selecting a few rows or columns from a larger dataframe based on specific criteria. frame(0,matrix(0, nrow = 4, ncols = 6) B <- as. frame(0,matrix(0, nrow = 5, ncols = 6) C <- as. There are these following four types of function in apply () function family: Feb 25, 2013 · I have a dataframe with multiple columns. May 2, 2016 · I want to apply a function to every row of a data frame. , values Mar 26, 2018 · Using the purrr package to iterate over lots of values and return a data frame. Dec 29, 2018 · This function works fine if I use it on one column, but since I have a number of individuals, I would like to use the apply () family to use the function on multiple columns of one dataframe (for instance on columns 1:8 of the dataframe below): Apr 6, 2023 · Same function over multiple data frames General ramgouveia April 6, 2023, 9:15am 1 Aug 8, 2019 · The way you have your code written it seems like there are variable mix -ups. Automating these tasks with a function can save time and reduce errors. And yes, two of those methods use functions from the apply family! Feb 19, 2021 · Apply the ifelse function across a range of multiple R data frame columns. dfs Jun 20, 2021 · This tutorial explains how to apply a function to each row of a matrix or data frame in R, including examples. The tutorial consists of the following information: Jun 27, 2022 · This tutorial explains how to apply a function to each row of a data frame using dplyr, including examples. For I am trying to extract individual data frames (so getting a list or vector of data frames) split by the column containing the "user" identifier, to isolate the actions of a single actor. tree package in R to turn that into a tree. You can do this in several ways, depending on the value you specify to the MARGIN argument, which is usually set to 1, 2 or c(1, 2). First, I’ll show how to use the apply function by row: May 27, 2024 · This tutorial explains how to use the sapply() function with multiple arguments in R, including an example. Discover how to efficiently apply several functions on a list of data frames in R using `lapply`, along with creating and exporting the output files. , sum, mean) across a vector, matrix, or data frame. Jul 17, 2021 · This solution seemed promising (R - Apply function on multiple data frames) but everything I put in position 3 inside the lapply function is ignored as an unused argument. x), and . Jul 15, 2025 · In Python Pandas, we have the freedom to add different functions whenever needed like lambda function, sort function, etc. For example, Feb 7, 2015 · I have a list of data frames and have given each element in the list (e. By using do. We can use the absence of an outer name as a convention that you want to unpack a data frame column into individual columns. frame to an array which means all the columns must have the same type. This comprehensive guide covers syntax, practical examples, troubleshooting tips, and best practices for R programmers looking to streamline their data analysis workflows. How to open all data files from a directory and apply functions to each data frame in R - R programming example code - R tutorial - Detailed explanations - Reproducible R code in RStudio Apr 28, 2016 · I've figured out how to read one log (one day) into R as a data. We also learned about the special conditions of programming with {dplyr}, which demands a working understanding of environment and data variables. Introduction Data frames are the backbone of data analysis in R, and knowing how to efficiently process their rows is a crucial skill for any R programmer. Jul 23, 2025 · In this article, we will discuss how to apply a function to each row in a data frame in R Programming Language. Suppose you have a list of data frames, and you want to apply a specific function to each of them, such as summarizing the mean of a column. Sep 19, 2023 · Alternatives to apply() While the apply() function is a powerful tool for matrix and array manipulations, R provides a family of related functions designed to offer similar functionality across different data structures. apply () Use the apply () function when you want to apply a function to the rows or columns of a matrix or data frame. Aug 10, 2017 · I have multiple data frames and would like to take the same action across an identically named column in each data frame. drop = TRUE Mar 30, 2020 · I am applying the same function to multiple dataframes. Some example data (3 different data frames, but the problem I'm workin Jan 25, 2017 · R- apply a function to a multiple data frames, data frame names to be pulled from another dataframe Asked 8 years, 1 month ago Modified 8 years, 1 month ago Viewed 2k times Aug 5, 2020 · This tutorial explains the differences between the built-in R functions apply (), sapply (), lapply (), and tapply () along with examples of when and how to use each function. Whether you’re working with lists, vectors, or data frames, understanding how to use lapply() effectively can greatly enhance your programming efficiency. Objects passed to the function are Series objects whose index is either the DataFrame’s index (axis=0) or the DataFrame’s columns (axis=1). frame(0,matrix(0, nrow = 4, ncols = 4) D <- as. Sep 6, 2025 · Learn how to use dplyr across in R to apply functions across columns, reduce repetitive code, and simplify data wrangling. data, . txt files (around 300) in a directory. Offers an alternative to explicit iteration using for() loop; can be simpler and faster, though not always. For those of you familiar with ‘for’ loops, th We can use data frames to allow summary functions to return multiple columns. The lapply function is part of the apply family functions in R and allows applying a function over a list or a vector, returning a list. We can apply a lambda function to both the columns and rows of the Pandas data frame. Since this question is marked as duplicate, I gave a detailed answer with example on the question Simultaneously merge multiple data. frames in a list. re-ordering factors levels of a factor which is present in all of the data frames: May 31, 2022 · In this post, I will share my favorite methods for applying the same process to multiple data frames in R. call () to apply the desired function dynamically: Jul 23, 2025 · In this article, we are going to learn how to apply a function to each group using dplyr in the R programming language. Among its many features, the lapply() function stands out as a versatile tool for simplifying code and reducing redundancy. , sum(), mean()) across a vector, list, matrix, or data frame. For example, I want to merge the column2 and column3 in df1. See full list on r-coder. This is an example of pipe operation in dplyr: Aug 29, 2013 · lapply is probably a better choice than apply here, as apply first coerces your data. I was able to do a for loop to read the multiple CSVs and create the dataframes but couldn't get a for loop to work to use str_pad across the same column in dataframes. frames per group, we can loop through the list and apply a function to each one using whatever looping approach we prefer. My example below should address that. call () to apply the desired function dynamically: How to separate a data frame using a loop in R - R programming example code - Tutorial - Complete syntax in RStudio Jul 10, 2017 · Example: Joining multiple data frames A more useful example would be joining multiple data frames with the same ids but different other columns. The dplyr package in R is used for data manipulations and modifications. Dec 27, 2023 · For loops are a fundamental construct in many programming languages that allow you to repeat a section of code multiple times. Using apply, the result is not itself a data frame again, it looks more like a list or matrix? (I don't know enough R to be able to tell fro How To Use the apply function (matrix or data frame) How To Use the sapply function (simplified version of lapply) How To Use the lapply function (list or vector) How To Use the mapply function (applying a function to multiple lists or vectors) How To Use the tapply function (levels of a factor) While Loops For Loops Creating Anonymous Aug 18, 2015 · Use Reduce(function(dtf1,dtf2) left_join(dtf1,dtf2,by="index"), list(x,y,z)). I would like to apply the function to each row of the matrix and get a n-vector. May 31, 2022 · In this tutorial, we'll learn about the apply() function in R, including when to use it and why it's more efficient than loops. if_any () and if_all () apply the same predicate function to a selection of columns and combine the results into a single logical vector: if_any () is TRUE when the Jan 3, 2013 · Apply a function to rows inside multiple data. Mar 28, 2012 · R-bloggers. frame(0,matrix(0, nrow = 3, ncols = 5) list. What is dplyr? dplyr is a powerful and efficient data manipulation package in R. y. , values Apply a function along an axis of the DataFrame. g. data. Can a function be made to return multiple data frames? Sure, return multiple objects in a list, like say lm does or any number of other functions in the base distribution of R. call() with "rbind" as the function argument, we can seamlessly combine all data frames in our list into a single, row-combined data frame. inform = FALSE, . Closed 12 years ago. We can use data frames to allow summary functions to return multiple columns. We’ll use the purrr package. Operations that can be performed on a list of DataFrames are: Creating a list of Dataframes. Applying Lambda Functions How to merge multiple data frames in a list simultaneously - 2 R programming examples - Base R vs tidyverse (dplyr & purrr) - merge & reduce functions Do you want to do a calculation over multiple data frames, then write the results of the calculation to a separate file (for each data frame), and then run an analysis on each of your new data frames? Apr 18, 2019 · @unisateur It depends on your data structures, but if you specifically want a list of any objects, using list is safer as it will always behave that way. So, for example, I want to apply the function mean to the columns x and y for when z=3 and apply the function mean to the columns x and y for when z=1. Aug 22, 2013 · Using this as a function to change column names across multiple data frames contained in a list like this was incredibly helpful. The data frames specified as arguments in this function may have different lengths. This family of functions helps us to apply a certain function to a certain data frame, list, or vector and return the result as a list or vector depending on the function we use. In this post, we'll explore how to efficiently handle this task using the apply family of functions, particularly mapply and Map. Jul 23, 2025 · The apply () collection is a part of R essential package. I was just using it for illustrative purposes - my real function is much more complicated so I was wondering how the above code (and probably my function) could be changed so that it is applied for all the different data frames (and doesn't just use the in built functions in R). I'm not very familiar with R, so all the help I've looked at online about looping is confusing, or I can't work out how to apply a loop when you need to apply multiple commands to each file. variables, . across () makes it easy to apply the same transformation to multiple columns, allowing you to use select () semantics inside in "data-masking" functions like summarise () and mutate (). This article will guide you through building a function in R that loops through multiple data frames and applies transformations to them. Suppose I have a n by 2 matrix and a function that takes a 2-vector as one of its arguments. 🧩 Here's how R-Coder applied this solution to their code: Jan 10, 2022 · I want to apply several different functions simultaneously to one dataframe, then put the results into a list of dataframes. Jun 28, 2022 · This tutorial explains how to use the apply() function only on specific data frame columns in R, including examples. For completeness, group_modify(), group_map and group_walk() also work on ungrouped data frames, in that case the function is applied to the entire data frame (exposed as . In this tutorial we will review how to use the lapply function in R with several examples. frame(x = c(1:5), y = c(11:15)) mylist <- list(A = df1, B = df2) I have a function that I want to apply to each data frame; In this function, I want to include a line to write the results to file (eventually I want to do more The apply command in R allows you to apply a function across an array, matrix or data frame. Depending on your context, this could have unintended consequences. May 18, 2021 · In R, how to change columns in multiple data frames inside a list using map() not lmap(). frame(x = c(1:5), y = c(11:15)) df2 <- data. Now, I want to recursively go through all of the files in the directory, one by one, and add them to that original data. A very typical task in data analysis is calculation of summary statistics for each variable in data frame. Understanding the Problem You might have data structured in two Jun 14, 2018 · I would like to apply the same operation to multiple data frames in 'R' but cannot get how to deal with this matter. 1 Now we want to apply our functions, row-by-row, to a data frame. Example: Suppose we have a dummy dataset with A, B, C as column names and some numeric value as rows. More details: https://statisticsglobe. The article looks as follows: May 23, 2019 · I have two data frames with the same columns, and similar content. To give an example, if data1, 2 and 3 were dataframes, then the c( function will make a big list with all their columns, not a list of 3 dataframes like list does. The apply function takes data frames as input and can be applied by the rows or by the columns of a data frame. So, for example, I could arrange by one column, then save the output as Nov 2, 2013 · I have data frames A, B, C, and want to modify each data frame in the same way, e. After applying this function, the df1 will get a new column called col2_col3. Dec 8, 2024 · Question: Is there a procedure to apply a function to many data frames in a way that changes those dataframes directly? I looked at many questions and answers, but they were basically the above strategy. ---This Sep 14, 2021 · R offers a family of apply functions, which allow you to apply a function across different chunks of data. bn7vdmoqxqpbktqpgnoe3zlioddkemkz6rhntweg