How can I convert row names into the first column?

Question

I have a data frame like this:

df
              VALUE              ABS_CALL DETECTION P-VALUE    
    1007_s_at "957.729231881542" "P"      "0.00486279317241156"
    1053_at   "320.632701283368" "P"      "0.0313356324173416" 
    117_at    "429.842323161046" "P"      "0.0170004527476119" 
    121_at    "2395.7364289242"  "P"      "0.0114473584876183" 
    1255_g_at "116.493632746934" "A"      "0.39799368200131"   
    1294_at   "739.927122116896" "A"      "0.0668649772942343"

I want to convert the row names into the first column. Currently I use something like this to make row names as the first column:

  d <- df
  names <- rownames(d)
  rownames(d) <- NULL
  data <- cbind(names,d)

Is there a single line to do this?

possible duplicate of [R: converting row names in multiple data frames to column in data frame](http://stackoverflow.com/questions/18403199/r-converting-row-names-in-multiple-data-frames-to-column-in-data-frame) — rmuc8, Apr 08 '15 at 09:50
You don't need extra packages, here's a one-liner: `d <- cbind(rownames(d), data.frame(d, row.names=NULL))` — ssp3nc3r, Oct 06 '17 at 20:13

score 231 · Accepted Answer · edited Nov 27 '21 at 03:37

231

Or you can use tibble's rownames_to_column which does the same thing as David's answer:

library(tibble)
df <- tibble::rownames_to_column(df, "VALUE")

Note: The earlier function called add_rownames() has been deprecated and is being replaced by tibble::rownames_to_column()

edited Nov 27 '21 at 03:37

Kevin Wright

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answered Apr 08 '15 at 10:04

hrbrmstr

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Not *exactly* the same, because it's not doing it *by reference* :) – David Arenburg Apr 08 '15 at 10:09
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UPDATE: dplyr update requires one to use tibble::rownames_to_column() since dplyr::rownames is deprecated. – EDennnis May 13 '19 at 15:27
This is great if one wants to stay within the tidyverse – Euler_Salter Dec 28 '19 at 15:11

David Arenburg · Answer 2 · 2019-02-05T12:01:14.777

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You can both remove row names and convert them to a column by reference (without reallocating memory using ->) using setDT and its keep.rownames = TRUE argument from the data.table package

library(data.table)
setDT(df, keep.rownames = TRUE)[]
#    rn     VALUE  ABS_CALL DETECTION     P.VALUE
# 1:  1 1007_s_at  957.7292         P 0.004862793
# 2:  2   1053_at  320.6327         P 0.031335632
# 3:  3    117_at  429.8423         P 0.017000453
# 4:  4    121_at 2395.7364         P 0.011447358
# 5:  5 1255_g_at  116.4936         A 0.397993682
# 6:  6   1294_at  739.9271         A 0.066864977

As mentioned by @snoram, you can give the new column any name you want, e.g. setDT(df, keep.rownames = "newname") would add "newname" as the rows column.

edited Feb 05 '19 at 12:01

answered Apr 08 '15 at 09:53

David Arenburg

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Use ``colnames(df)[1] <- "newname"`` to rename the first column if needed. – Swetabh Nov 16 '16 at 05:24
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@Swetabh Well, no. `setnames(df, 1, "newname")` is the `data.table` way. – David Arenburg Nov 16 '16 at 07:45
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@DavidArenburg Well, (at least) now you can do it in the same call `setDT(df, keep.rownames = "newname")[]` – s_baldur Feb 05 '19 at 11:11
@snoram to do what at the same call? – David Arenburg Feb 05 '19 at 11:24
@DavidArenburg setting the name from within the `setDT()` call - no need for `setnames()` – s_baldur Feb 05 '19 at 11:25
@snoram Interesting, I haven't seen it documented anywhere – David Arenburg Feb 05 '19 at 11:31
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@DavidArenburg found in documentation for `as.data.table()`: *If TRUE, adds the input object's names as a separate column named "rn". keep.rownames = "id" names the column "id" instead* – s_baldur Feb 05 '19 at 11:35
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@snoram good find, I'll make a PR regarding that to make docs consistent. – David Arenburg Feb 05 '19 at 11:38

score 115 · Answer 3 · edited Oct 06 '17 at 19:42

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A one line option is :

df$names <- rownames(df)

edited Oct 06 '17 at 19:42

Jaap

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answered Mar 18 '16 at 12:21

Emily

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I hope you are aware of the fact that it adds `rownames` as a column at the last, indeed not as a first column. – Agaz Wani Mar 18 '16 at 12:28
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After to remove index use `rownames(df) <- NULL` – vasili111 May 12 '21 at 17:33
@vasili111 - could you explain what does it mean by 'to remove index' as I see no difference to the data table before (df$names <- rownames(df)) and after (rownames(df) <- NULL). Do you mean it stores the index column internally? – Aravindan Kalai Jun 29 '22 at 21:18
@AravindanKalai Hi. `rownames(df) <- NULL` will remove original row names. I was referring to row names. – vasili111 Jul 01 '22 at 16:10

score 39 · Answer 4 · answered Mar 30 '17 at 17:55

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Alternatively, you can create a new dataframe (or overwrite the current one, as the example below) so you do not need to use of any external package. However this way may not be efficient with huge dataframes.

df <- data.frame(names = row.names(df), df)

answered Mar 30 '17 at 17:55

drasc

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Or: `df <- cbind(names = rownames(df), df)` – Mark Miller Jun 13 '17 at 20:47

score 29 · Answer 5 · answered Mar 27 '19 at 13:43

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Moved my comment into an answer per suggestion above:

You don't need extra packages, here's a one-liner:

d <- cbind(rownames(d), data.frame(d, row.names=NULL))

answered Mar 27 '19 at 13:43

ssp3nc3r

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score 8 · Answer 6 · edited Aug 22 '21 at 07:18

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dplyr::as_tibble(df, rownames = "your_row_name") will give you even simpler result.

edited Aug 22 '21 at 07:18

Dima Lituiev

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answered Jun 01 '19 at 15:37

SteveS

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@HectorHaffenden have edited this for the poster, because it's actually a nice suggestion. – tjebo Jul 26 '19 at 10:55
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"`as_data_frame()` was deprecated in tibble 2.0.0. Please use `as_tibble()` instead." Otherwise this is my favourite. – Samuel Saari May 05 '21 at 16:05

score 4 · Answer 7 · answered Jan 23 '22 at 19:38

4

Change data rownames as a real column

data <- data %>%
  rownames_to_column(var="the name you want")

answered Jan 23 '22 at 19:38

marianthi

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score 3 · Answer 8 · edited Jul 02 '20 at 05:37

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Or by using DBIs sqlRownamesToColumn

library(DBI)
sqlRownamesToColumn(df)

edited Jul 02 '20 at 05:37

UseR10085

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answered Nov 22 '19 at 22:53

Agaz Wani

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score 2 · Answer 9 · edited Sep 08 '22 at 01:34

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df = data.frame(columnNameILike = row.names(df), df, row.names=NULL)

edited Sep 08 '22 at 01:34

M.Viking

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answered Mar 12 '21 at 20:09

Yale Liu

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How can I convert row names into the first column?

9 Answers9

Change data rownames as a real column

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