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---
title: "Column types"
output: rmarkdown::html_vignette
vignette: >
%\VignetteIndexEntry{Column types}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---
```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>"
)
library(dplyr)
library(tidyr)
library(purrr)
requireNamespace("hms", quietly = TRUE)
```
```{r setup}
library(tibble)
```
## Overview
This vignette shows an overview of known data types and their abbreviations, and their origin.
For example, `<int>` in the header of a column indicates an integer column, and `<chr>` denotes a character column.
```{r howto, echo = FALSE, eval = FALSE}
library(tidyverse)
library(tidymodels)
library(vctrs)
library(pillar)
all_methods <-
c("vec_ptype_abbr", "vec_ptype_full", "type_sum") %>%
map(methods) %>%
map(as.character) %>%
map(~ gsub("^.*[.]", "", .x)) %>%
unlist() %>%
unique()
set_names(rep_along(all_methods, list("")), all_methods) %>%
dput()
```
```{r data, echo = FALSE}
data <- list(
"Atomic" = rlang::quos(
logical = TRUE,
integer = 1L,
double = 1.5,
character = "A",
complex = 1i,
raw = as.raw(1),
list = list(1),
"named list" = list(a = 1)
),
"Built-in objects" = rlang::quos(
factor = factor("A"),
ordered = ordered("a"),
Date = Sys.Date(),
POSIXt = Sys.time(),
difftime = vctrs::new_duration(1)
),
"Objects from other packages" = rlang::quos(
hms = hms::hms(1),
integer64 = bit64::as.integer64(1e10),
blob = blob::blob(raw(1))
),
"Data frames" = rlang::quos(
data.frame = data.frame(a = 1),
tbl_df = tibble(a = 1)
),
"Unchanged" = rlang::quos(
AsIs = I(1L)
),
"vctrs types" = rlang::quos(
unspecified = vctrs::unspecified(1),
vctrs_list_of = vctrs::list_of(c(1L)),
vctrs_vctr = vctrs::new_vctr(1L),
vctrs_partial_factor = vctrs::partial_factor(letters),
vctrs_partial_frame = vctrs::partial_frame(a = 1)
),
"Language objects" = rlang::quos(
"function" = function() NULL,
symbol = quote(a),
expression = parse(text = "a <- 1\nb<- 2"),
quosures = rlang::quos(a = 1)
)
)
```
```{r table, echo = FALSE}
tbl <-
data %>%
map(unclass) %>%
map(enframe, "Data type", "Expression") %>%
enframe("Class", "data") %>%
unnest(data) %>%
mutate(Example = map_chr(Expression, rlang::as_label)) %>%
mutate(Value = map(Expression, rlang::eval_tidy)) %>%
select(-Expression) %>%
mutate(Class = if_else(Class == lag(Class, default = ""), "", Class)) %>%
mutate("Column header" = map_chr(Value, type_sum))
```
```{r kable, echo = FALSE}
tbl %>%
select(-Value) %>%
mutate(Example = paste0("`", Example, "`")) %>%
knitr::kable(escape = FALSE)
```
## Example values
The following overview contains example values for each type:
```{r glimpse, echo = FALSE}
tbl %>%
select(`Data type`, `Value`) %>%
filter(map_lgl(Value, vctrs::vec_is)) %>%
deframe() %>%
as_tibble() %>%
glimpse()
```
## Implementation
The column header is obtained by calling `pillar::type_sum()` on the column.
This is an S3 method that can be overridden,
but most of the time it is more useful to override `vctrs::vec_ptype_abbr()`:
```{r type_sum_default, results = if (Sys.getenv("IN_GALLEY") != "") "hide" else "markup"}
pillar:::type_sum.default
```
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