Hello community!
I have a dataframe where all characters are in uppercase. What options do you recommend to convert it to lowercase?
Thank you for your help.
Hello,
I would use the str_to_lower function from the stringr package to do this.
Here is an example:
# loading packages
library(dplyr)
#>
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>
#> filter, lag
#> The following objects are masked from 'package:base':
#>
#> intersect, setdiff, setequal, union
library(stringr)
library(tibble)
# creating fake data
fake_data <- tibble(
char_1 = replicate(n = 100, expr = paste0(sample(x = LETTERS, size = 10, replace = TRUE), collapse = "")),
char_2 = replicate(n = 100, expr = paste0(sample(x = LETTERS, size = 10, replace = TRUE), collapse = "")),
char_3 = replicate(n = 100, expr = paste0(sample(x = LETTERS, size = 10, replace = TRUE), collapse = ""))
)
# converting character data to lowercase
fake_data |>
mutate(across(.cols = where(is.character), .fns = str_to_lower))
#> # A tibble: 100 × 3
#> char_1 char_2 char_3
#> <chr> <chr> <chr>
#> 1 tlybnwoxvb bsdmjylqnn zooowlavdx
#> 2 lmtwfashdx jbmipkwzsf qzdmfqvviz
#> 3 vmdbclanzs xoogmwqrzj ifokfyxqgn
#> 4 qlyumyaemg xzlewkwqwm xytnofxzyl
#> 5 wresynkvdf nqvrmsaygx ssfjumdaic
#> 6 cklucwlkfv ffpbtypvsw xlczqbriut
#> 7 dhmphycdow ofdiepfrte dcwryurron
#> 8 vdglaygngj txlgjypwbd wvgainofez
#> 9 hrejxaydos opxqlcosls svvxpzapch
#> 10 mzlkdosfkn gohkxpzpwv hfbzfelnzk
#> # ℹ 90 more rows
Created on 2025-10-16 with reprex v2.1.1
Session info
sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#> setting value
#> version R version 4.5.1 (2025-06-13)
#> os macOS Sequoia 15.6.1
#> system x86_64, darwin20
#> ui X11
#> language (EN)
#> collate en_US.UTF-8
#> ctype en_US.UTF-8
#> tz America/Toronto
#> date 2025-10-16
#> pandoc 3.6.3 @ /Applications/RStudio.app/Contents/Resources/app/quarto/bin/tools/x86_64/ (via rmarkdown)
#> quarto 1.7.31 @ /usr/local/bin/quarto
#>
#> ─ Packages ───────────────────────────────────────────────────────────────────
#> package * version date (UTC) lib source
#> cli 3.6.5 2025-04-23 [1] RSPM
#> digest 0.6.37 2024-08-19 [1] RSPM
#> dplyr * 1.1.4 2023-11-17 [1] RSPM
#> evaluate 1.0.5 2025-08-27 [1] RSPM
#> fastmap 1.2.0 2024-05-15 [1] RSPM
#> fs 1.6.6 2025-04-12 [1] RSPM
#> generics 0.1.4 2025-05-09 [1] RSPM
#> glue 1.8.0 2024-09-30 [1] RSPM
#> htmltools 0.5.8.1 2024-04-04 [1] RSPM
#> knitr 1.50 2025-03-16 [1] RSPM
#> lifecycle 1.0.4 2023-11-07 [1] RSPM
#> magrittr 2.0.4 2025-09-12 [1] RSPM
#> pillar 1.11.1 2025-09-17 [1] RSPM
#> pkgconfig 2.0.3 2019-09-22 [1] RSPM
#> R6 2.6.1 2025-02-15 [1] RSPM
#> reprex 2.1.1 2024-07-06 [1] RSPM
#> rlang 1.1.6 2025-04-11 [1] RSPM
#> rmarkdown 2.30 2025-09-28 [1] RSPM
#> rstudioapi 0.17.1 2024-10-22 [1] RSPM
#> sessioninfo 1.2.3 2025-02-05 [1] RSPM
#> stringi 1.8.7 2025-03-27 [1] RSPM
#> stringr * 1.5.2 2025-09-08 [1] RSPM
#> tibble * 3.3.0 2025-06-08 [1] RSPM
#> tidyselect 1.2.1 2024-03-11 [1] RSPM
#> utf8 1.2.6 2025-06-08 [1] RSPM
#> vctrs 0.6.5 2023-12-01 [1] RSPM
#> withr 3.0.2 2024-10-28 [1] RSPM
#> xfun 0.53 2025-08-19 [1] RSPM
#> yaml 2.3.10 2024-07-26 [1] RSPM
#>
#> [1] /Users/timothychisamore/Library/R/x86_64/4.5/library
#> [2] /Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/library
#> * ── Packages attached to the search path.
#>
#> ──────────────────────────────────────────────────────────────────────────────
All the best,
Tim
Adding to Tim’s reply, you can also use base R and {tidyverse} to achieve this!
Base R
# Convert a single column
df$col <- tolower(df$col)
# Convert all character columns
df[] <- lapply(df, function(x)
if(is.character(x)) tolower(x) else x)
Tidyvers
df <- df %>%
mutate(across(where(is.character), tolower))
Best,
Luis
1 Like