Convert Data.Frame Columns from Factors to Characters

Convert data.frame columns from factors to characters

Just following on Matt and Dirk. If you want to recreate your existing data frame without changing the global option, you can recreate it with an apply statement:

bob <- data.frame(lapply(bob, as.character), stringsAsFactors=FALSE)

This will convert all variables to class "character", if you want to only convert factors, see Marek's solution below.

As @hadley points out, the following is more concise.

bob[] <- lapply(bob, as.character)

In both cases, lapply outputs a list; however, owing to the magical properties of R, the use of [] in the second case keeps the data.frame class of the bob object, thereby eliminating the need to convert back to a data.frame using as.data.frame with the argument stringsAsFactors = FALSE.

Convert dataframe numeric column to character

I think you can do that and that should work :

coldata$Station<-as.character(coldata$Station)

convert all factor columns to character in a data.frame without affecting non-factor columns

You can try:

library(tidyverse)
d <- data.frame(a = 1:5, 
                b = factor(c("a", "b", "c", "d", "e")), 
                c = factor(c("f", "g", "h", "i", "j")))
d %>% glimpse() 
Observations: 5
Variables: 3
$ a <int> 1, 2, 3, 4, 5
$ b <fctr> a, b, c, d, e
$ c <fctr> f, g, h, i, j

d %>% 
  mutate_if(is.factor, as.character) %>% 
  glimpse()
Observations: 5
Variables: 3
$ a <int> 1, 2, 3, 4, 5
$ b <chr> "a", "b", "c", "d", "e"
$ c <chr> "f", "g", "h", "i", "j"

Using base R you can try

d[] <- lapply(d, function(x) if(is.factor(x)) as.character(x) else x)

Convert all columns to characters in a data.frame

EDIT: 2021-03-01

Beginning with dplyr 1.0.0, the _all() function variants are superceded. The new way to accomplish this is using the new across() function.

library(dplyr)
mtcars %>%
  mutate(across(everything(), as.character))

With across(), we choose the set of columns we want to modify using tidyselect helpers (here we use everything() to choose all columns), and then specify the function we want to apply to each of the selected columns. In this case, that is as.character().

Original answer:

You can also use dplyr::mutate_all.

library(dplyr)
mtcars %>%
  mutate_all(as.character)

Convert data.frame column format from character to factor

Hi welcome to the world of R.

mtcars  #look at this built in data set
str(mtcars) #allows you to see the classes of the variables (all numeric)

#one approach it to index with the $ sign and the as.factor function
mtcars$am <- as.factor(mtcars$am)
#another approach
mtcars[, 'cyl'] <- as.factor(mtcars[, 'cyl'])
str(mtcars)  # now look at the classes

This also works for character, dates, integers and other classes

Since you're new to R I'd suggest you have a look at these two websites:

R reference manuals:
http://cran.r-project.org/manuals.html

R Reference card: http://cran.r-project.org/doc/contrib/Short-refcard.pdf

Convert all data frame character columns to factors

DF <- data.frame(x=letters[1:5], y=1:5, stringsAsFactors=FALSE)

str(DF)
#'data.frame':  5 obs. of  2 variables:
# $ x: chr  "a" "b" "c" "d" ...
# $ y: int  1 2 3 4 5

You can use as.data.frame to turn all character columns into factor columns:

DF <- as.data.frame(unclass(DF),stringsAsFactors=TRUE)
str(DF)
#'data.frame':  5 obs. of  2 variables:
# $ x: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5
# $ y: int  1 2 3 4 5

How to convert data.frame column from Factor to numeric

breast$class <- as.numeric(as.character(breast$class))

If you have many columns to convert to numeric

indx <- sapply(breast, is.factor)
breast[indx] <- lapply(breast[indx], function(x) as.numeric(as.character(x)))

Another option is to use stringsAsFactors=FALSE while reading the file using read.table or read.csv

Just in case, other options to create/change columns

 breast[,'class'] <- as.numeric(as.character(breast[,'class']))

or

 breast <- transform(breast, class=as.numeric(as.character(breast)))

How do I convert all numeric columns to character type in my dataframe?

In base R, we may either use one of the following i.e. loop over all the columns, create an if/else conditon to change it

dataframe[] <- lapply(dataframe, function(x) if(is.numeric(x)) 
           as.character(x) else x)

Or create an index for numeric columns and loop only on those columns and assign

i1 <- sapply(dataframe, is.numeric)
dataframe[i1] <- lapply(dataframe[i1], as.character)

---

It may be more flexible in dplyr

library(dplyr)
dataframe <- dataframe %>%
        mutate(across(where(is.numeric), as.character))

Convert entire data frame to character class with R dplyr

We just don't need the () as it returns character(0) because it expects an argument in the invocation process. The function expression is evaluated, but the argument expression is empty resulting in a zero length output as the value of the invocation expression

as.character()
#character(0)

library(dplyr)
mtcars %>%
     as_tibble() %>% 
     mutate_all(as.character)

and this has the same effect as

mtcars %>%
      as_tibble %>%
      mutate_all(character(0))

In the newer versions, use mutate with across

mtcars %>%
    mutate(across(everything(), as.character))

If we are using as.character() use it with anonymous function call

mtcars %>%
     as_tibble() %>% 
     mutate_all(~ as.character(.))

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