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In R, the easiest way to repeat rows is with the REP() function. This function selects one or more observations from a data frame and creates one or more copies of them. Alternatively, you can use the SLICE() function from the dplyr package to repeat rows.
In the Copy and insert rows & columns dialog box, select Copy and insert rows option in the Type section, then select the data range you want to duplicate, and then specify the repeat time to duplicate the rows, see screenshot: 4.
How to repeat column values in R data frame by values in another column? First of all, create a data frame. Then, use rep function along with cbind function to repeat column values in the matrix by values in another column.
Here's one solution:
df.expanded <- df[rep(row.names(df), df$freq), 1:2]
Result:
var1 var2
1 a d
2 b e
2.1 b e
3 c f
3.1 c f
3.2 c f
old question, new verb in tidyverse:
library(tidyr) # version >= 0.8.0
df <- data.frame(var1=c('a', 'b', 'c'), var2=c('d', 'e', 'f'), freq=1:3)
df %>%
uncount(freq)
var1 var2
1 a d
2 b e
2.1 b e
3 c f
3.1 c f
3.2 c f
Use expandRows() from the splitstackshape package:
library(splitstackshape)
expandRows(df, "freq")
Simple syntax, very fast, works on data.frame or data.table.
Result:
var1 var2
1 a d
2 b e
2.1 b e
3 c f
3.1 c f
3.2 c f
@neilfws's solution works great for data.frames, but not for data.tables since they lack the row.names property. This approach works for both:
df.expanded <- df[rep(seq(nrow(df)), df$freq), 1:2]
The code for data.table is a tad cleaner:
# convert to data.table by reference
setDT(df)
df.expanded <- df[rep(seq(.N), freq), !"freq"]
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