Menu
How can I delete every n-th row from a dataframe in R?
923
To delete a row from a DataFrame, use the drop() method and set the index label as the parameter.
To select every nth row of a DataFrame - we will use the slicing method. Slicing in pandas DataFrame is similar to slicing a list or a string in python. Suppose we want every 2nd row of DataFrame we will use slicing in which we will define 2 after two :: (colons).
To delete rows and columns from DataFrames, Pandas uses the “drop” function. To delete a column, or multiple columns, use the name of the column(s), and specify the “axis” as 1. Alternatively, as in the example below, the 'columns' parameter has been added in Pandas which cuts out the need for 'axis'.
We can remove the last n rows using the drop() method. drop() method gets an inplace argument which takes a boolean value. If inplace attribute is set to True then the dataframe gets updated with the new value of dataframe (dataframe with last n rows removed).
You could create a function as follows
Nth.delete<-function(dataframe, n)dataframe[-(seq(n,to=nrow(dataframe),by=n)),]
Let's test it out
DF<-data.frame(A=1:15, B=rnorm(15), C=sample(LETTERS,15))
Nth.delete(DF, 3)
I wish to add the tidyverse style approach to this problem, using the %% operator.
library(dplyr)
df <- data.frame(V1 = seq(26), V2 = letters)
df %>% filter(row_number() %% 2 != 0) ## Delete even-rows
df %>% filter(row_number() %% 2 != 1) ## Delete odd-rows
df %>% filter(row_number() %% 3 != 1) ## Delete every 3rd row starting from 1
You can use the same idea to select every n-th row, of course. See here
44
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
