Overview I’m relatively familiar with data.table, not so much with dplyr. I’ve read through some dplyr vignettes and examples that have popped up on SO, and so far my conclusions are that: data.table and dplyr are comparable in speed, except when there are many (i.e. >10-100K) groups, and in some other circumstances (see benchmarks below) … Read more
What are the differences between the assignment operators = and <- in R? I know that operators are slightly different, as this example shows x <- y <- 5 x = y = 5 x = y <- 5 x <- y = 5 # Error in (x <- y) = 5 : could not … Read more
I have a data frame and some columns have NA values. How do I replace these NA values with zeroes? 26 s 26 See my comment in @gsk3 answer. A simple example: > m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10) > d <- as.data.frame(m) V1 V2 V3 V4 V5 V6 V7 V8 V9 … Read more
I have a number of columns that I would like to remove from a data frame. I know that we can delete them individually using something like: df$x <- NULL But I was hoping to do this with fewer commands. Also, I know that I could drop columns using integer indexing like this: df <- … Read more
I’d like to remove the lines in this data frame that: a) contain NAs across all columns. Below is my example data frame. gene hsap mmul mmus rnor cfam 1 ENSG00000208234 0 NA NA NA NA 2 ENSG00000199674 0 2 2 2 2 3 ENSG00000221622 0 NA NA NA NA 4 ENSG00000207604 0 NA NA … Read more
Whenever I want to do something “map”py in R, I usually try to use a function in the apply family. However, I’ve never quite understood the differences between them — how {sapply, lapply, etc.} apply the function to the input/grouped input, what the output will look like, or even what the input can be — … Read more
I want to sort a data frame by multiple columns. For example, with the data frame below I would like to sort by column ‘z’ (descending) then by column ‘b’ (ascending): dd <- data.frame(b = factor(c(“Hi”, “Med”, “Hi”, “Low”), levels = c(“Low”, “Med”, “Hi”), ordered = TRUE), x = c(“A”, “D”, “A”, “C”), y = … Read more
Given two data frames: df1 = data.frame(CustomerId = c(1:6), Product = c(rep(“Toaster”, 3), rep(“Radio”, 3))) df2 = data.frame(CustomerId = c(2, 4, 6), State = c(rep(“Alabama”, 2), rep(“Ohio”, 1))) df1 # CustomerId Product # 1 Toaster # 2 Toaster # 3 Toaster # 4 Radio # 5 Radio # 6 Radio df2 # CustomerId State # … Read more
This question’s answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. When discussing performance with colleagues, teaching, sending a bug report or searching for guidance on mailing lists and here on Stack Overflow, a reproducible example is often asked and always helpful. What are … Read more
