Linked Questions
28 questions linked to/from How to drop columns by name in a data frame
8
votes
0
answers
28k
views
Select all columns except specific (by name) in R? [duplicate]
I have the following dataframe:
a b c d e
1 rr dfv 5 0.1
9 t rr1 222 0.44
7 sdf we 1 0.111
I want to select all columns except say d and e.
I know I can use subset for this: ...
2
votes
0
answers
9k
views
How to remove column by name from R matrix? [duplicate]
I know how to remove columns by name from R dataframe, but I can not figure out how to do it in matrix. I want to do something like this:
> m <- matrix(1:6, nrow=2, ncol = 3)
> colnames(m) &...
1
vote
1
answer
3k
views
Exclude columns in R calling column names [duplicate]
Suppose I have a matrix called mymat. I need to exclude columns key and AMLM12014N-R and make another matrix called newmat. I can simply do this like this: newmat <- mymat[,-c(1,4)], but is there a ...
- 5,747
1
vote
1
answer
790
views
R referring to dataframe columns by label to delete them [duplicate]
An easy one I suppose though my searches have been pretty fruitless --
given
z=data.frame(X.39=rnorm(20),X.40=rnorm(20),X.51=rnorm(20))
the subsetting operation
z[,c('X.39','X.51')]
works. but
z[,...
- 6,038
1
vote
2
answers
108
views
Why doesn’t mtcars[, -c("mpg"), drop = F] work? [duplicate]
This works:
mtcars[, c("mpg"), drop = F]
mpg
Mazda RX4 21.0
Mazda RX4 Wag 21.0
Datsun 710 22.8
Hornet 4 Drive 21.4
Hornet Sportabout 18....
- 3,364
0
votes
1
answer
96
views
How to drop multiple columns in R using select?I just don't know where to put the “-” [duplicate]
Create the dataframe taxis_smaller that excludes the columns VendorID, rate, and store_and_fwd_flag.
taxis_smaller <- taxis %>% select(taxis,-c("VendorID","rate","store_and_fwd_flag"))
select(...
- 1
0
votes
0
answers
66
views
Very basic subsetting issue [duplicate]
I have a dataframe of about 4000 x 50000, and I have a variable "x" which contains the name of the variables I would like to drop from the dataframe. Here's an example of what my data looks like:
df &...
- 7,161
0
votes
0
answers
66
views
Why subset doesn't work with string column names when removing columns? [duplicate]
Consider the following dataframe:
df <- data.frame(x=1:5, y=6:10, z=11:15, a=16:20)
I can select a column using just the name:
df2 <- subset (df, select = x)
Or I can select it passing the ...
- 5,151
0
votes
0
answers
28
views
Errors when using subset and select [duplicate]
I am using subset and select to extract columns from a dataframe. My code is simple, however errors occur.
names(df7)
df7 <- subset(df7, select = -c("Parameter.Code", "Time.Local", "Date.GMT", "...
- 595
0
votes
0
answers
35
views
Remove columns with -c() [duplicate]
I know that one should be able to delete columns with -c() and the column names. But weirdly it doesn't work in my R. What am I doing wrong?
library(data.table)
df <- data.frame(x1=c(1,2,3), x2=c(4,...
0
votes
0
answers
19
views
how can I add a column name as an argument to a function? [duplicate]
Im creating a function to run cor.test for all the columns on a data frame, except the column that is added in the argument. I want the argument (ref) to be the column name, buy when I actually use ...
1052
votes
25
answers
2.0m
views
Drop data frame columns by name
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 ...
- 40.4k
449
votes
2
answers
111k
views
Why is `[` better than `subset`?
When I need to filter a data.frame, i.e., extract rows that meet certain conditions, I prefer to use the subset function:
subset(airquality, Month == 8 & Temp > 90)
Rather than the [ function:
...
- 89.3k
41
votes
4
answers
190k
views
How to delete specific rows and columns from a matrix in a smarter way?
Let's say t1 is :
t1 <- array(1:20, dim=c(10,10))
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 11 1 11 1 11 1 11 1 11
[2,] 2 12 2 12 2 ...
- 615
8
votes
5
answers
51k
views
How to select range of columns in a dataframe based on their name and not their indexes?
In a pandas dataframe created like this:
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randint(10, size=(6, 6)),
columns=['c' + str(i) for i in range(6)],
...
- 26.2k