Changing Class of Column Across Multiple Dataframes

Question

I have a list of 59 data frames that I want to merge together. Unfortunately, because I have scraped many of them, the columns in the data frames have different classes. They all have the column "Name", some in factor form and some in character form. I want to change all of them to character form. I tried the following

dts <- c("Alabama","Alaska","Arizona","Arkansas","California","Colorado","Connecticut","Delaware","Florida",
               "Georgia","Hawaii","Idaho","Illinois","Indiana","Iowa","Kansas","Kentucky","Louisiana","Maine",
               "Maryland","Massachusetts","Michigan","Minnesota","Mississippi","Missouri","Montana","Nebraska",
               "Nevada","New_Hampshire","New_Jersey","New_Mexico","New_York","North_Carolina","North_Dakota",
               "Ohio","Oklahoma","Oregon","Pennsylvania","Rhode_Island","South_Carolina","South_Dakota","Tennessee",
               "Texas","Utah","Vermont","Virginia","Washington","West_Virginia","Wisconsin","Wyoming","Federal",
               "CCJail","DC","LAJail","NOLA","NYCJail","OCJail","PhilJail","TXJail")


for(i in 1:length(dts)){
        dts[i]$Name <- as.character(dts[i]$Name)
}

but it only gave me the error "Error: $ operator is invalid for atomic vectors". Does anyone know of a good work-around? Thanks in advance for the help!

My ultimate goal is to run

dta <-dplyr::bind_rows(Alabama,Alaska,Arizona,Arkansas,California,Colorado,Connecticut,Delaware,Florida,
       Georgia,Hawaii,Idaho,Illinois,Indiana,Iowa,Kansas,Kentucky,Louisiana,Maine,
       Maryland,Massachusetts,Michigan,Minnesota,Mississippi,Missouri,Montana,Nebraska,
       Nevada,New_Hampshire,New_Jersey,New_Mexico,New_York,North_Carolina,North_Dakota,
       Ohio,Oklahoma,Oregon,Pennsylvania,Rhode_Island,South_Carolina,South_Dakota,Tennessee,
       Texas,Utah,Vermont,Virginia,Washington,West_Virginia,Wisconsin,Wyoming,Federal,CCJail,
       DC,LAJail,NOLA,NYCJail,OCJail,PhilJail,TXJail)

But I get the error "Error: Can't combine ..1$Residents.Confirmed and ..2$Residents.Confirmed ." There are a ton of columns in each data frame, and they are different classes very often. if anyone has a more elegant solution, I would also be open to that instead! Thanks!

Do you need to change only the 'Name' column class or all the columns? — akrun
– akrun, Commented Jun 27, 2020 at 4:37
@arkun I ned to change all the columns (some to character, some to numeric). Thanks! — babybonobo
– babybonobo, Commented Jun 27, 2020 at 4:39
That is not clear. Because it may also vary in each of the datasets. I have added a solution to change all the character and then bind them — akrun
– akrun, Commented Jun 27, 2020 at 4:40

akrun · Accepted Answer · 2020-06-27 04:44:04Z

2

We can get the datasets loaded into a list with mget (assuming the dataset objects are already created in the global environment) and then loop over the list with map, change the class of 'Name' column in mutate and row bind with suffix _dfr in map

library(dplyr)
library(purrr)
out <- map_dfr(mget(dts), ~ .x %>% 
                  mutate(Name = as.character(Name)))

If there are many columns that are different class. May be, it is better to convert to a single class for all the columns and then bind

out <- map_dfr(mget(dts), ~ .x %>%
                   mutate(across(everything(), as.character)))
out <- type.convert(out, as.is = TRUE)

If the dplyr version is < 1.0.0, use mutate_all

out <- map_dfr(mget(dts), ~ .x %>%
               mutate_all(as.character))

edited Jun 27, 2020 at 4:44

answered Jun 27, 2020 at 4:31

akrun

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7 Comments

babybonobo Over a year ago

Thanks for the help! Right now, when I run code you suggested, it gives the following error: Error: Problem with mutate() input ..1. x Can't recycle ..1 (size 507) to match ..20 (size 22). ℹ Input ..1 is across(everything(), as.character).

babybonobo Over a year ago

and when I run rlang::last_error() I get <error/dplyr_error> Problem with mutate() input ..1. x Can't recycle ..1 (size 507) to match ..20 (size 22). ℹ Input ..1 is across(everything(), as.character). Backtrace: 1. purrr::map_dfr(...) 2. purrr::map(.x, .f, ...) 3. global::.f(.x[[i]], ...) 12. dplyr::mutate(., across(everything(), as.character)) 14. dplyr:::mutate_cols(.data, ...)

akrun Over a year ago

@babybonobo what is the version of dplyr I used 1.0.0

akrun Over a year ago

@babybonobo can you try with mutate_all as in the update

babybonobo Over a year ago

I'm using 1.0.0. Thanks for the help! I tried the mutate_all option but now it's giving me the error of Error: Invalid index: out of bounds

|

chase171 · Accepted Answer · 2020-06-27 04:42:46Z

1

d1 <- data.frame(
  Name = as.factor(c("name1", "name2")),
  Residents.Confirmed = c(0,1)
  )
d2 <- data.frame(
  Name = c("name3", "name4"),
  Residents.Confirmed = c(2,3)
)
dataframes_list <- list(d1, d2)
for(i in 1:length(dataframes_list)){
  dataframes_list[[i]]$Name <- as.character(dataframes_list[[i]]$Name)
}
bind_rows(dataframes_list)

answered Jun 27, 2020 at 4:42

chase171

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Comments

hello_friend · Accepted Answer · 2020-06-27 05:49:13Z

-1

Base R solution:

type.convert(do.call("rbind", 
        Map(function(x){data.frame(lapply(x, as.character))}, dataframes_list)))

Data thanks @chase171:

d1 <- data.frame(
  Name = as.factor(c("name1", "name2")),
  Residents.Confirmed = c(0,1)
)
d2 <- data.frame(
  Name = c("name3", "name4"),
  Residents.Confirmed = c(2,3)
)
dataframes_list <- list(d1, d2)

answered Jun 27, 2020 at 5:49

hello_friend

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