The following df has a list column (CVcCVq) that has a single numeric value. I would like to extract this single value into another column or convert this list column into a numeric column.
I have used the below code to extract elements of a list in the past (e.g., by using .x$value), but I cannot figure out how to reference the unnamed(?) value in (CVcCVq):
df <-
df %>%
mutate(CVcCVq = map_dbl(CVcCVq, ~ .x$value))
Here is a sample of the dataframe I'm working with:
df <-
structure(list(site = c("Hungerford", "Hungerford", "Hungerford",
"Hungerford", "Hungerford", "Hungerford"), date = structure(c(16244,
16244, 16244, 16244, 16245, 16245), class = "Date"), q = c(0.13302763934,
0.13302763934, 0.13302763934, 0.13302763934, 0.118154355, 0.118154355
), year = c(2014, 2014, 2014, 2014, 2014, 2014), var = c("DOC",
"NO3", "SRP", "turb", "DOC", "NO3"), value = c(8.41162692329658,
2.68458225207895, 0.0100915159605364, 8.0213, 8.23726061695833,
2.49696316297646), CVcCVq = list(0.129399469450364, 0.504972938773432,
1.13463616961327, 0.602451097752468, 0.129399469450364, 0.504972938773432)), row.names = c(NA,
-6L), groups = structure(list(site = c("Hungerford", "Hungerford",
"Hungerford", "Hungerford"), year = c(2014, 2014, 2014, 2014),
var = c("DOC", "NO3", "SRP", "turb"), .rows = structure(list(
c(1L, 5L), c(2L, 6L), 3L, 4L), ptype = integer(0), class = c("vctrs_list_of",
"vctrs_vctr", "list"))), row.names = c(NA, -4L), class = c("tbl_df",
"tbl", "data.frame"), .drop = TRUE), class = c("grouped_df",
"tbl_df", "tbl", "data.frame"))
You can use unlist(), unnest(), or extract with subsetting [[ here.
I recommend you stick with unnest() here. It is more consistent and clear, and easier to use if you have multiple nested list columns.
library(dplyr)
df %>% mutate(CVcCVq = unlist(CVcCVq))
#OR
library(dplyr)
library(tidyr)
df %>% unnest(cols = CVcCVq)
#OR
df %>% mutate(CVcCVq = `[[`(CVcCVq, 1))
#OR
df %>% mutate(CVcCVq = CVcCVq[[1]])
# A tibble: 6 x 7
# Groups: site, year, var [4]
site date q year var value CVcCVq
<chr> <date> <dbl> <dbl> <chr> <dbl> <dbl>
1 Hungerford 2014-06-23 0.133 2014 DOC 8.41 0.129
2 Hungerford 2014-06-23 0.133 2014 NO3 2.68 0.505
3 Hungerford 2014-06-23 0.133 2014 SRP 0.0101 1.13
4 Hungerford 2014-06-23 0.133 2014 turb 8.02 0.602
5 Hungerford 2014-06-24 0.118 2014 DOC 8.24 0.129
6 Hungerford 2014-06-24 0.118 2014 NO3 2.50 0.505
You can also use a variant of your own code:
df%>%mutate(CVcCVq=map_dbl(CVcCVq, ~.x))