_{Sum across columns in r Edit: In hindsight, I should have titled this "Sum across multiple columns by vector of column names." Problem. I have a dataset with 17 columns that I want to combine into 4 by summing subsets of columns together. For the sake of reusable code, I want to avoid using indexes or manually typing all the column names, and instead use a vector of ... }

_{This tutorial explains how to use this function to calculate the cumulative sum of a vector along with how to visualize a cumulative sum. How to Calculate a Cumulative Sum in R. The following code shows how to calculate the cumulative sum of sales for a given company over the course of 15 sales quarters: I have 4 columns in a dataframe of 244 columns. I need to do a sum over these columns, which can be done with a simple sum function. However, the sum is not taking into consideration the nas. So when I run: df <- d%>% rowwise () %>% mutate (DV = sum (x1, x2, x3, x4, na.rm=TRUE)) I am getting 0, when all the values are NA, I would like to get NA ...logical. Should missing values (including NaN ) be omitted from the calculations? dims. integer: Which dimensions are regarded as ‘rows’ or ‘columns’ to sum over. For row*, the sum or mean is over dimensions dims+1, ...; for col* it is over dimensions 1:dims. m, n. the dimensions of the matrix x for .colSums () etc.2. Group By Sum in R using dplyr. You can use group_by() function along with the summarise() from dplyr package to find the group by sum in R DataFrame, group_by() returns the grouped_df ( A grouped Data Frame) and use summarise() on grouped df results to get the group by sum.Apr 3, 2020 · across () has two primary arguments: The first argument, .cols, selects the columns you want to operate on. It uses the tidy select syntax so you can pick columns by position, name, function of name, type, or any combination thereof using Boolean operators. The second argument, .fns, is a function or list of functions to apply to each column. Calculating Sum Column and ignoring Na [duplicate] Closed 5 years ago. I am trying to create a Total sum column that adds up the values of the previous columns. However I am having difficulty if there is an NA. If there is an NA in the row, my script will not calculate the sum. How do I edit the following script to essentially count the NA's as ...Basic usage across () has two primary arguments: The first argument, .cols, selects the columns you want to operate on. It uses tidy selection (like select () ) so you can pick variables by position, name, and type. The second argument, .fns, is a function or list of functions to apply to each column.The idea is to transpose the data so that the columns become rows, then apply the rowsum function to sum up these rows indexed by the same group label. Transposing again returns the data to its original form, now with the columns with the same labels summed up. If one needs to use R functions to calculate values across columns within a row, one can use the rowwise() function to prevent mutate() from using multiple rows in the functions on the right hand side of equations within mutate(). To illustrate, we'll sum the values of vs, am. Notice that the result of n = n() in the output is 1 for each row ...I wanna use the Summarise (across (where))-command in order to generate the total weight and the weight for each person. This is what I have tried until now. data_2 <- read_excel ("data_2.xlsx", sheet = 2) data_2 %>% summarise (across (where (is.numeric), sum)) Unfortunately, this don't work correctly. Does anyone have an idea on how to solve this?Original Answer: I would use summarise_at, and just make a logical vector which is FALSE for non-numeric columns and Registered and TRUE otherwise, i.e. df %>% summarise_at (which (sapply (df, is.numeric) & names (df) != 'Registered'), sum) If you wanted to just summarise all but one column you could do.Nov 19, 2022 · ID Sum PSM ABC 2 CCC 58 DDD 56 EEE 80 FFF 1 GGG 90 KOO 45 LLL 4 ZZZ 8 ... R summarize unique values across columns based on values from one column. 8. sum multiple columns based on column value. Original Post by jjoe. jjoe. 12:32 ... Hi, I have a table to be imported for R as matrix or data.frame but I first ...I hope that it may help you. Some cases you have a few columns that are not numeric.This approach will serve you both. Note that: c_across() for dplyr version 1.0.0 and laterSummarise multiple columns. Scoped verbs ( _if, _at, _all) have been superseded by the use of pick () or across () in an existing verb. See vignette ("colwise") for details. The scoped variants of summarise () make it easy to apply the same transformation to multiple variables. There are three variants.In R, simplifying long data.table commands (probably combining Data.table's "group by", lapply, and a vector of column names) -2 Summary table with some columns summing over a vector with variables in R An option using data.table.Specify the columns (.SDcols) that we need to get the sum ('nm1'), use Reduce to sum the corresponding elements of those columns, assign (:=) the output to new column ('eureka') (should be very fast for big datasets as it add columns by reference)Jun 17, 2021 · Method 2 : Using lapply () The data.table library can be installed and loaded into the working space. The lapply () method can then be applied over this data.table object, to aggregate multiple columns using a group. The lapply () method is used to return an object of the same length as that of the input list. To subtract in Excel, enter the numbers in a cell using the formula =x-y, complete the same formula using the column and row headings of two different cells, or use the SUM function with negative numbers. Excel does not have a specific SUBT...1 Answer. We can place the datasets in a list, use rbindlist to rbind the datasets, grouped by 'ship_no', get the sum of other columns. library (data.table) rbindlist (list (df1, df2), fill = TRUE) [,lapply (.SD, sum, na.rm = TRUE) , ship_no] # ship_no bay_1 bay_2 bay_3 bay_5 bay_6 bay_7 #1: ABC 10 20 15 20 30 10 #2: DEF 20 30 0 40 20 0 #3: ERT ...It contains 2 columns with categories and 2 columns with numerical values. That will help to demonstrate how to solve different needs for sum by the group in R. Calculate the sum by a group in R using dplyr. With functions from dplyr, you can solve multiple scenarios when it is necessary to sum by a group. Here is a simple one. Kroger troy pharmacy. Sep 24, 2020 · I would like to calculate the number of missing response within columns that start with Q62 and then from columns Q3_1 to Q3_5 separately. I know that rowSums is handy to sum numeric variables, but is there a dplyr/piped equivalent to sum na's? For example, if this were numeric data and I wanted to sum the q62 series, I could use the following: Here are some more examples of how to summarise data by group using dplyr functions using the built-in dataset mtcars: # several summary columns with arbitrary names mtcars %>% group_by (cyl, gear) %>% # multiple group columns summarise (max_hp = max (hp), mean_mpg = mean (mpg)) # multiple summary columns # summarise all columns except grouping ... I always had trouble with aggregate syntax when trying to do more than one thing at a time. Here you want to sum two existing columns and compute a brand new column. Using dplyr: library (dplyr) df %>% group_by (Vehicle, Driver) %>% summarize (Distance = sum (Distance), Fuel.Consumption = sum (Fuel.Consumption), …df %>% group_by (g1, g2) %>% summarise ( across (a:d, mean)) We’ll start by discussing the basic usage of across () , particularly as it applies to summarise (), and show how to …Or using summarise with across (dplyr devel version - ‘0.8.99.9000 ... R sum values in two columns based on two index columns leaving NA values-4. Group by and count based on muliple conditions in R. See more linked questions. Related. 1176. Group By Multiple Columns. 1487.The colSums() function in R can be used to calculate the sum of the values in each column of a matrix or data frame in R. This function uses the following basic syntax: colSums(x, na.rm=FALSE) where: x: Name of the matrix or data frame. na.rm: Whether to ignore NA values. Default is FALSE. The following examples show how to use this function in ... I have a dataframe in R with several columns called "SECOND1" , .... "SECOND54" and "SECONDother". I want to create a new column and add the sum of the values for each row across all columns that start with "SECOND" and are followed by a number in their column name.Learn three methods to sum values across multiple columns of a data frame using dplyr, a powerful tool for data analysis in R. See examples with a basketball data …Value. across() typically returns a tibble with one column for each column in .cols and each function in .fns.If .unpack is used, more columns may be returned depending on how the results of .fns are unpacked.. if_any() and if_all() return a logical vector. Timing of evaluation. R code in dplyr verbs is generally evaluated once per group. Inside across() …From my data below, I'd like to be able to count the NA's rowwise that appear in first, last, address, phone, and state columns (exlcuding m_initial and customer in the count). first m_initial last address phone state customer Bob L Turner 123 Turner Lane 410-3141 Iowa NA Will P Williams 456 Williams Rd 491-2359 NA Y Amanda C Jones 789 …Jun 22, 2021 · The rowSums() function in R can be used to calculate the sum of the values in each row of a matrix or data frame in R. This function uses the following basic syntax: rowSums(x, na.rm=FALSE) where: x: Name of the matrix or data frame. na.rm: Whether to ignore NA values. Default is FALSE. The following examples show how to use this function in ... Conditional summing across columns with dplyr. Ask Question Asked 5 years, 11 months ago. Modified 4 years, 6 months ago. Viewed 2k times Part of R Language Collective 2 I have a data frame with four habitats sampled over eight months. Ten samples were collected from each habitat each month.Learn three methods to sum values across multiple columns of a data frame using dplyr, a powerful tool for data analysis in R. See examples with a basketball data frame and the code for each method.Microsoft Excel is packed with useful data management features that don’t see a lot of use, like pivot tables, index and match, and conditional formatting. If you’re just using excel to sum and chart columns, this graphic can show you some ...Combine values from multiple columns. c_across () is designed to work with rowwise () to make it easy to perform row-wise aggregations. It has two differences from c (): It uses tidy select semantics so you can easily select multiple variables. See vignette ("rowwise") for more details. It uses vctrs::vec_c () in order to give safer outputs. R newb, I'm trying to calculate the cumulative sum grouped by year, month, group and subgroup, also having multiple columns to calculate. Sample of the data: df <- data.frame("Year"=20...I always had trouble with aggregate syntax when trying to do more than one thing at a time. Here you want to sum two existing columns and compute a brand new column. Using dplyr: library (dplyr) df %>% group_by (Vehicle, Driver) %>% summarize (Distance = sum (Distance), Fuel.Consumption = sum (Fuel.Consumption), … 1. Update II (but will work with the first update as well) With base R, we can first create a new grouping column, where we copy the Topic column as factor, then we can change the levels according to what rows you want to group together to sum. Then, we can get the sum of the Gamma column by the Topic and row groups. Sep 24, 2020 · I would like to calculate the number of missing response within columns that start with Q62 and then from columns Q3_1 to Q3_5 separately. I know that rowSums is handy to sum numeric variables, but is there a dplyr/piped equivalent to sum na's? For example, if this were numeric data and I wanted to sum the q62 series, I could use the following: Here is a tidyverse solution using c_across which is designed for row-wise aggregations. This makes it easy to refer to columns by name, ... How I can calculate the means for different columns in R-1. How to get a mean of multiple column values using R dplyr-2. R: Averaging columns and conditionally excluding NA data ...For one column (X2), the data can be aggregated to get the sums of all rows that have the same X1 value: > ddply (df, . (X1), summarise, X2=sum (X2)) X1 X2 1 a 4 2 b 5 3 c 8.I would like to get the average for certain columns for each row. w=c (5,6,7,8) x=c (1,2,3,4) y=c (1,2,3) length (y)=4 z=data.frame (w,x,y) I would like to get the mean for certain columns, not all of them. My problem is that there are a lot of NAs in my data. So if I wanted the mean of x and y, this is what I would like to get back:As you can see, we have added +100 to the first two columns of our data. The third column was kept as in the original input data, since the while-loop stopped at the second column. Example 4: repeat-Loop Through Columns of Data Frame. Similar to while-loops, we can also use a repeat-loop to loop over the variables of a data frame. Again, we ...Which provides an extra column with totals for the rows But I'm not sure how to add Columns to the dataframe while also retaining all existing values I've tried this but it doesn't work.1 Answer. We can place the datasets in a list, use rbindlist to rbind the datasets, grouped by 'ship_no', get the sum of other columns. library (data.table) rbindlist (list (df1, df2), fill = TRUE) [,lapply (.SD, sum, na.rm = TRUE) , ship_no] # ship_no bay_1 bay_2 bay_3 bay_5 bay_6 bay_7 #1: ABC 10 20 15 20 30 10 #2: DEF 20 30 0 40 20 0 #3: ERT ... 6ft nutcracker at costco. Uf flexible learning. Basic usage across () has two primary arguments: The first argument, .cols, selects the columns you want to operate on. It uses tidy selection (like select () ) so you can pick variables by position, name, and type. The second argument, .fns, is a function or list of functions to apply to each column.Closed 4 years ago. Summing across columns by listing their names is fairly simple: iris %>% rowwise () %>% mutate (sum = sum (Sepal.Length, Sepal.Width, Petal.Length)) However, say there are a lot more columns, and you are interested in extracting all columns containing "Sepal" without manually listing them out.Here columns_to_sum is the variable that saves the names of the columns you wish to apply rowSums on. I hope this helps. Share. Improve this answer. Follow edited Sep 9, 2016 at 22:12. answered Sep ... Sum elements across a list of data.frames. 0. Summing a dataframe with lapply. 2.Method 2 : Using lapply () The data.table library can be installed and loaded into the working space. The lapply () method can then be applied over this data.table object, to aggregate multiple columns using a group. The lapply () method is used to return an object of the same length as that of the input list.Next, we how and rowSums () function into cumulative the values across columns in R for each row the the dataframe, which returns a vector of row sums. We will add a new pillar called Row_Sums to the source dataframe df, using to assignment operative <- and the $ host in ROENTGEN to determine the new bar name. A way to add a column with the sum across all columns uses the cbind function: cbind (data, total = rowSums (data)) This method adds a total column to the data and avoids the alignment issue yielded when trying to sum across ALL columns using the above solutions (see the post below for a discussion of this issue).sum cells of certain columns for each row Ask Question Asked 10 years, 10 months ago Modified Viewed 92k times Part of R Language Collective 25 I would like to calculate sums for certain columns and then apply this summation for every row. Unfortunately, I can only get to the first step. How do I now make it happen for each row?If a variable, computes sum(wt) for each group. sort. If TRUE, will show the largest groups at the top. name. The name of the new column in the output. If omitted, it will default to n. If there's already a column called n, it will use nn. If there's a column called n and nn, it'll use nnn, and so on, adding ns until it gets a new name..dropFeb 25, 2015 · An option using data.table.Specify the columns (.SDcols) that we need to get the sum ('nm1'), use Reduce to sum the corresponding elements of those columns, assign (:=) the output to new column ('eureka') (should be very fast for big datasets as it add columns by reference) The original function was written by Terry Therneau, but this is a new implementation using hashing that is much faster for large matrices. To sum over all the rows of a matrix (i.e., a single group) use colSums, which should be even faster. For integer arguments, over/underflow in forming the sum results in NA. ID Sum PSM ABC 2 CCC 58 DDD 56 EEE 80 FFF 1 GGG 90 KOO 45 LLL 4 ZZZ 8 ... R summarize unique values across columns based on values from one column. 8. …. R: Summing a sequence of columns row-wise with dplyr. In the spirit of similar questions along these lines here and here, I would like to be able to sum across a sequence of columns in my data_frame & create a new column: df_abc = data_frame ( FJDFjdfF = seq (1:100), FfdfFxfj = seq (1:100), orfOiRFj = seq (1:100), xDGHdj = seq (1:100), jfdIDFF ...Mar 5, 2015 · My question involves summing up values across multiple columns of a data frame and creating a new column corresponding to this summation using dplyr. The data entries in the columns are binary (0,1). I am thinking of a row-wise analog of the summarise_each or mutate_each function of dplyr. Below is a minimal example of the data frame: You can use function colSums() to calculate sum of all values. [,-1] ensures that first column with names of people is excluded. colSums(people[,-1]) Height Weight 199 425 Assuming there could be multiple columns that are not numeric, or that your column order is not fixed, a more general approach would be: colSums(Filter(is.numeric, people))To group all factor columns and sum numeric columns : df %>% group_by (across (where (is.factor))) %>% summarise (across (where (is.numeric), sum)) We can also do this by position but have to be careful of the number since it doesn't count the grouping columns.First, we will create a vector with some NA values and then apply the sum () function without any additional arguments. # create a vector with NA values. vec <- c(1, 2, NA, 3, NA) # sum of values in vector. sum(vec) Output: <NA>. You can see that we get NA as the output. This is because summing anything with NA results in NA in R.2023/07/12 ... The most straightforward way to sum columns based on a condition in R is by using the subset() function along with the sum() function. The ...In the above example, c_across() is used to select columns ‘a’ and ‘c’, and rowwise() is used to perform row-wise operations on the selected columns. The mutate() function is used to create a new column named sum_cols, which contains the sum of values in columns ‘a’ and ‘c’. Using starts_with(), ends_with()3. For operations like sum that already have an efficient vectorised row-wise alternative, the proper way is currently: df %>% mutate (total = rowSums (across (where (is.numeric)))) across can take anything that select can (e.g. rowSums (across (Sepal.Length:Petal.Width)) also works).Dec 8, 2014 · 3. For operations like sum that already have an efficient vectorised row-wise alternative, the proper way is currently: df %>% mutate (total = rowSums (across (where (is.numeric)))) across can take anything that select can (e.g. rowSums (across (Sepal.Length:Petal.Width)) also works). Sum across columns in r, Adding to @GregorThomas comment. Please mind the coding style: spaces after comma, lower-case names for vars, no space between function name and opening bracket, pipes are designed to make code more readable - place your calls after the pipe to a new line, nested ifelse calls are confusing. Also, you don't need to create variables, …, This tells us that the value 30 or 26 appear a total of 3 times in the ‘points’ column. Additional Resources. How to Sum Specific Columns in R How to Calculate the Mean of Multiple Columns in R How to Find the Max Value Across Multiple Columns in R, I'm new to R. The professor asked us to obtain sum, mean and variance for several columns of data which are in Excel form. Now, I want to try to use R to solve them rather than enter the formula in Excel and drag. I have imported the data into R and they are correctly displayed. I can use the commands sum and sd and var for EACH column., 2023/07/12 ... The most straightforward way to sum columns based on a condition in R is by using the subset() function along with the sum() function. The ..., Sum across multiple columns with pattern conditionally. -1. I want to sum across multiple columns that have a particular pattern for the column name. The following works: sum = rowSums (across (matches ('pattern')), na.rm = TRUE) However, I want to only sum if the value is 1 or NA (0). So if the value is 2 for example, it will ignore it and ..., I would like to sum the columns Var1 and Var2, which I use: a$sum<-a$Var_1 + a$Var_2 In reality my data set is much larger - I would like to sum from Var_1 …, Sum across multiple columns with dplyr. 3. Using R, data.table, conditionally sum columns. Hot Network Questions Why "suam" and not "eius" is used in this sentence? The Son of man coming with the clouds or on a horse? ..., dplyr::mutate to add multiple values (7 answers) Closed 5 years ago. I am trying to figure out how to add multiple columns returned from a function which takes one or multiple columns from the same data frame as input - basically, I want mutate but with the option to left_join () a data frame. I can do this with either left_join () or cbind ..., How to sum columns and rows in a wide R dataframe? Ask Question Asked 1 year, 8 months ago. Modified 1 year, 8 months ago. ... (Total = rowSums(across(where(is.numeric)))) Which provides an extra column with totals for the rows But I'm not sure how to add Columns to the dataframe while also retaining all …, < tidy-select > Columns to transform. You can't select grouping columns because they are already automatically handled by the verb (i.e. summarise () or mutate () ). .fns Functions to apply to each of the selected columns. Possible values are: A function, e.g. mean. A purrr-style lambda, e.g. ~ mean (.x, na.rm = TRUE), across() typically returns a tibble with one column for each column in .cols and each function in .fns. If .unpack is used, more columns may be returned depending on how the results of .fns are unpacked. if_any() and if_all() return a logical vector. Timing of evaluation. R code in dplyr verbs is generally evaluated once per group., More generally, create a key for each observation (e.g., the row number using mutate below), move the columns of interest into two columns, one holds the column name, the other holds the value (using melt below), group_by observation, and do whatever calculations you want., It contains 2 columns with categories and 2 columns with numerical values. That will help to demonstrate how to solve different needs for sum by the group in R. Calculate the sum by a group in R using dplyr. With functions from dplyr, you can solve multiple scenarios when it is necessary to sum by a group. Here is a simple one., You can use function colSums() to calculate sum of all values. [,-1] ensures that first column with names of people is excluded. colSums(people[,-1]) Height Weight 199 425 Assuming there could be multiple columns that are not numeric, or that your column order is not fixed, a more general approach would be: colSums(Filter(is.numeric, people)), Sum across multiple columns with dplyr. 3. Using R, data.table, conditionally sum columns. Hot Network Questions Why "suam" and not "eius" is used in this sentence? The Son of man coming with the clouds or on a horse? ..., I have a dataframe in R with several columns called "SECOND1" , .... "SECOND54" and "SECONDother". I want to create a new column and add the sum of the values for each row across all columns that start with "SECOND" and are followed by a number in their column name., Method 1: Calculate Cumulative Sum of One Column. df %>% mutate(cum_sum = cumsum(var1)) Method 2: Calculate Cumulative Sum by Group. df %>% group_by(var1) %>% mutate(cum_sum = cumsum(var2)) The following examples show how to use each method in practice. Example 1: Calculate Cumulative Sum Using dplyr. …, Sum of multiple columns. We can calculate the sum of multiple columns by using rowSums() and c() Function. we simply have to pass the name of the columns. Syntax: rowSums(dataframe[ , c(“column1”, “column2”, “column n”)]) where. dataframe is the input dataframe; c() represents the number of columns to be specified to add; …, I need to summarize a data.frame across multiple columns in a generic way: the first summarize operation is easy, e.g. a simple median, and is straightforward; the second summarize then includes a condition on another column, e.g. taking the value where these is a minimum (by group) in another column:, First, we will create a vector with some NA values and then apply the sum () function without any additional arguments. # create a vector with NA values. vec <- c(1, 2, NA, 3, NA) # sum of values in vector. sum(vec) Output: <NA>. You can see that we get NA as the output. This is because summing anything with NA results in NA in R., To find the area under a curve using Excel, list the x-axis and y-axis values in columns A and B, respectively. Then, type the trapezoidal formula into the top row of column C, and copy the formula to all the rows in that column. Finally, d..., Basic usage across () has two primary arguments: The first argument, .cols, selects the columns you want to operate on. It uses tidy selection (like select () ) so you can pick variables by position, name, and type. The second argument, .fns, is a function or list of functions to apply to each column., Counting NAs across either rows or columns can be achieved by using the apply() function. This function takes three arguments: X is the input matrix, MARGIN is an integer, and FUN is the function to apply to each row or column. MARGIN = 1 means to apply the function across rows and MARGIN = 2 across columns. apply(X = is.na(mtcars), MARGIN = 1 ..., The summation of all individual rows can also be done using the row-wise operations of dplyr (with col1, col2, col3 defining three selected columns for which the row-wise sum is calculated): library (tidyverse) df <- df %>% rowwise () %>% mutate (rowsum = sum (c (col1, col2,col3))) Share. Improve this answer. Follow., Closed 4 years ago. Summing across columns by listing their names is fairly simple: iris %>% rowwise () %>% mutate (sum = sum (Sepal.Length, Sepal.Width, Petal.Length)) However, say there are a lot more columns, and you are interested in extracting all columns containing "Sepal" without manually listing them out., I have 4 columns in a dataframe of 244 columns. I need to do a sum over these columns, which can be done with a simple sum function. However, the sum is not taking into consideration the nas. So when I run: df <- d%>% rowwise () %>% mutate (DV = sum (x1, x2, x3, x4, na.rm=TRUE)) I am getting 0, when all the values are NA, I would like to get …, Viewed 6k times. Part of R Language Collective. 4. I am trying to use sum function inside dplyr's mutate function. However I am ending up with unexpected results. Below is the code to reproduce the problem. chk1 <- data.frame (ba_mat_x=c (1,2,3,4),ba_mat_y=c (NA,2,NA,5)) I used the below code to create another column that sums up the above 2 ..., Base solution using sapply and an annonymous function function(x){sum(is.na(x))}: ... Finding count of NA values for combination of columns in R. 3. Count all the NA values in one column of a dataframe. 4. Count NA in given columns by rows. 1. Counting over multiple columns, ignoring NA. 0., Don't think you need summarise_at, since your definition of add takes care fo the multiple input arguments.summarise_at is useful when you are applying the same change to multiple columns, not for combining them.. If you just want sum of the columns, you can try: iris %>% group_by(Species) %>% summarise_at( .vars= vars( …, To calculate the number of NAs in the entire data.frame, I can use sum(is.na(df), however, how can I count the number of NA in each column of a big data.frame? I tried apply(df, 2, function (x) sum..., sum cells of certain columns for each row Ask Question Asked 10 years, 10 months ago Modified Viewed 92k times Part of R Language Collective 25 I would like to calculate sums for certain columns and then apply this summation for every row. Unfortunately, I can only get to the first step. How do I now make it happen for each row?, I have a data frame where I would like to add an additional row that totals up the values for each column. For example, Let's say I have this data: x <- data.frame (Language=c ("C++", "Java", "Python"), Files=c (4009, 210, 35), LOC=c (15328,876, 200), stringsAsFactors=FALSE) Data looks like this: Language Files LOC 1 C++ 4009 15328 2 …, Now, I'd like to calculate a new column "sum" from the three var-columns. Unfortunately, in every row only one variable out of the three has a value: ... Summing across rows of a data.table for specific columns with NA. 0. Sum of na rows when column value is na , and other column value == "" ...}