This question already has answers here:
Extracting specific columns from a data frame
(10 answers)
Closed 4 years ago.
I have to extract two columns from this data set (Cars93 on MASS) and create a separate folder consisting only of the two columns MPG.highway and EngineSize. How do I go about doing this?
You can look at Cars93 on Mass and just get the first ten rows to see it.
You can create a subset using the names directly using the subset function or alternately,
new_df <- Cars93[,c("MPG.highway","EngineSize")]
#or
new_df <- subset(Cars93, keep = c("MPG.highway","EngineSize"))
Related
This question already has answers here:
how to remove multiple columns in r dataframe?
(8 answers)
Select column 2 to last column in R
(4 answers)
Closed 2 years ago.
I have a data frame that I import from excel each week with 40+ columns. Each week the data frame has a different number of columns, I am only interested in the first 40. I take the data frame, drop the columns after 40 and rbind to another data frame (that has 40 columns).
The code I use to drop the columns is"
df = df[ -c(40:45) ] #assume df has 45 columns this week.
I would like to find a step to automate the lendth of columns to drop, similar to length(df$x) type of idea. I try width(df) but doesn't seem to work?
Any ideas please?
This question already has answers here:
Why does apply convert logicals in data frames to strings of 5 characters?
(2 answers)
Selecting only numeric columns from a data frame
(12 answers)
Closed 2 years ago.
I know that the question is very easy, but I have a more specific one:
I have a data frame, with 50 variables (numeric and non-numeric) and 5000 observations.
Now what I want to do is create another data frame containing only the numerica variables of the original one.
On this website I found the solution of my problem, that is:
numeric_variables<-unlist(lapply(original_data,is.numeric))
X<-original_data[numeric_variables]
But I was wondering: why if I try like this, it does not work instead? what's wrong?
numeric_variables2<-apply(original_data,2,is.numeric)
x<-original_data[numeric_variables2]
try this :
names_num <- names(which(sapply(df, is.numeric)))
df_num <- df[, names_num]
This question already has answers here:
Extracting specific columns from a data frame
(10 answers)
Closed 4 years ago.
in R programming, how do I subset a matrix so that I can skip columns in between? I only know how to do it continuously such as 1:4, but what if I want the first, second, and fourth colum
You can select specific columns as follows:
new_df <- x[,c(1,2,4)]# Select column 1,2 and 4
This question already has answers here:
Extracting specific columns from a data frame
(10 answers)
Closed 6 years ago.
Does anybody know of a way to create a new data frame that contains the information of specific columns from a master data frame that has multiple columns? I have a master dataframe and I'm trying to run various tests (regression, ANOVA...etc.,) on specific columns in the data frame. Any suggestions would be greatly appreciated.
if you want to choose columns 3,12 and 15 from the old DF:
newDF <- oldDF[,c(3,12,15)]
if you want to remove columns 3,12 and 15 from the old DF:
newDF <- oldDF[,-c(3,12,15)]
This question already has answers here:
Sort (order) data frame rows by multiple columns
(19 answers)
Closed 6 years ago.
I want to sort a variable in the dataset.
la3 <-order(la1$Id)
Iam getting the output as index. How to get the output as real values in the datatset
la3 <-la1[order(la1$Id),]
The length of the order will correspond to the length of the column and specify the ordered position.
Using an index call of the original data will therefore put the rows in that order.
Using dplyr
library(dplyr)
la1 %>%
arrange(Id)