This question already has answers here:
Combine a list of data frames into one data frame by row
(10 answers)
Closed 1 year ago.
I have an object with each row being a dataframe or list itself like this:
[[1]]
1: a b c d
1 1 2 4
[[2]]
1: a b c d
4 3 6 2
[[3]]
1: a b c d
1 2 2 1
How can I transform this to a dataframe like below?
a b c d
1 1 2 4
4 3 6 2
1 2 2 1
We can use rbindlist
library(data.table)
rbindlist(lst1)
Or with rbind and do.call in base R
do.call(rbind, lst1)
Related
This question already has answers here:
Repeat each row of data.frame the number of times specified in a column
(10 answers)
Closed 3 years ago.
I have a data.frame with n rows and I would like to repeat this rows according to the observation of another variable
This is an example for a data.frame
df <- data.frame(a=1:3, b=letters[1:2])
df
a b
1 1 a
2 2 b
3 3 c
And this one is an example for a variable
df1 <- data.frame(x=1:3)
df1
x
1 1
2 2
3 3
In the next step I would like to repeat every row from the df with the observation of df1
So that it would look like this
a b
1 1 a
2 2 b
3 2 b
4 3 c
5 3 c
6 3 c
If you have any idea how to solve this problem, I would be very thankful
You simply can repeat the index like:
df[rep(1:3,df1$x),]
# a b
#1 1 a
#2 2 b
#2.1 2 b
#3 3 c
#3.1 3 c
#3.2 3 c
or not fixed to size 3
df[rep(seq_along(df1$x),df1$x),]
This question already has answers here:
Unique combination of all elements from two (or more) vectors
(6 answers)
Closed 5 years ago.
I just migrated from Python to R and I would like to know if there is any function in R which is similar to pandas.MultiIndex.from_product?
Example:
letters <- c('a', 'b')
numbers <- c(1, 2, 3)
df <- somefunction(letters, numbers)
df
letters numbers
1 a 1
2 a 2
3 a 3
4 b 1
5 b 2
6 b 3
Yes:
> letters <- c('a', 'b')
> numbers <- c(1, 2, 3)
> expand.grid(letters=letters, numbers=numbers)
letters numbers
1 a 1
2 b 1
3 a 2
4 b 2
5 a 3
6 b 3
You can also use CJ from the data.table package. It is faster. But the result is not an ordinary dataframe, it is a datatable:
> library(data.table)
> CJ(letters=letters, numbers=numbers)
letters numbers
1: a 1
2: a 2
3: a 3
4: b 1
5: b 2
6: b 3
This question already has answers here:
Sort (order) data frame rows by multiple columns
(19 answers)
Closed 7 years ago.
If I want to sort the Chrom# from ascending order (1 to 23) for each unique ID (as shown below there's multiple rows of same IDs, how to write the R code for it? eg) MB-0002, chrom from 1,1,1,2,4,22... etc. 1 chrom per row. I am new to R so any help would be appreciated. Thanks so much!
sample dataset
If you can use dplyr::arrange then you can easily sort by two variables.
tmp <- data.frame(id=c("a","a","b","a","b","c","a","b","c"),
value=c(3,2,4,1,2,1,7,4,3))
tmp
# id value
# 1 a 3
# 2 a 2
# 3 b 4
# 4 a 1
# 5 b 2
# 6 c 1
# 7 a 7
# 8 b 4
# 9 c 3
library(dplyr)
tmp %>% arrange(id, value)
# id value
# 1 a 1
# 2 a 2
# 3 a 3
# 4 a 7
# 5 b 2
# 6 b 4
# 7 b 4
# 8 c 1
# 9 c 3
FYI, an image doesn't work as a usable sample dataset.
This question already has answers here:
Split comma-separated strings in a column into separate rows
(6 answers)
Closed 6 years ago.
Sorry for the naive question but I have a dataframe like this:
n sp cap
1 1 a 3
2 2 b 3+2+4
3 3 c 2
4 4 d 1+5
I need to split the numbers separated by the add sign ("+") into new rows in order to the get a new dataframe like this below:
n sp cap
1 1 a 3
2 2 b 3
3 2 b 2
4 2 b 4
5 3 c 2
6 4 d 1
7 4 d 5
How can I do that? strsplit?
thanks in advance
We could use cSplit from splitstackshape
library(splitstackshape)
cSplit(df1, 'cap', sep="+", 'long')
# n sp cap
#1: 1 a 3
#2: 2 b 3
#3: 2 b 2
#4: 2 b 4
#5: 3 c 2
#6: 4 d 1
#7: 4 d 5
Or could do this in base R. Use strsplit to split the elements of "cap" column to substrings, which returns a list (lst), Replicate the rows of dataset by the length of each list element, subset the dataset based on the new index, convert the "lst" elements to "numeric", unlist, and cbind with the modified dataset.
lst <- strsplit(as.character(df1$cap), "[+]")
df2 <- cbind(df1[rep(1:nrow(df1), sapply(lst, length)),1:2],
cap= unlist(lapply(lst, as.numeric)))
This question already has answers here:
Repeat each row of data.frame the number of times specified in a column
(10 answers)
Closed 7 years ago.
I have a data frame with names by type and their frequencies. I'd like to expand this data frame so that the names are repeated according to their name-type frequency.
For example, this:
> df = data.frame(name=c('a','b','c'),type=c(0,1,2),freq=c(2,3,2))
name type freq
1 a 0 2
2 b 1 3
3 c 2 2
would become this:
> df_exp
name type
1 a 0
2 a 0
3 b 1
4 b 1
5 b 1
6 c 2
7 c 2
Appreciate any suggestions on a easy way to do this.
You can just use rep to "expand" your data.frame rows:
df[rep(sequence(nrow(df)), df$freq), c("name", "type")]
# name type
# 1 a 0
# 1.1 a 0
# 2 b 1
# 2.1 b 1
# 2.2 b 1
# 3 c 2
# 3.1 c 2
And there's a function expandRows in the splitstackshape package that does exactly this. It also has the option to accept a vector specifying how many times to replicate each row, for example:
expandRows(df, "freq")