# Formatting, printing and exporting tables

## The difference between a dataframe and its render

Most of objects encountered throughout the easystats packages are “tables”, i.e., a 2D matrix with columns and rows. In R, these objects are often, at their core, data frames. Let’s create one to use as an example:

    library(insight)
    library(dplyr)

    df <- data.frame(
      Variable = c(1, 3, 5, 3, 1),
      Group = c("A", "A", "A", "B", "B"),
      CI = c(0.95, 0.95, 0.95, 0.95, 0.95),
      CI_low = c(3.35, 2.425, 6.213, 12.1, 1.23),
      CI_high = c(4.23, 5.31, 7.123, 13.5, 3.61),
      p = c(0.001, 0.0456, 0.45, 0.0042, 0.34)
    )

    df
    #>   Variable Group   CI CI_low CI_high      p
    #> 1        1     A 0.95  3.350   4.230 0.0010
    #> 2        3     A 0.95  2.425   5.310 0.0456
    #> 3        5     A 0.95  6.213   7.123 0.4500
    #> 4        3     B 0.95 12.100  13.500 0.0042
    #> 5        1     B 0.95  1.230   3.610 0.3400

When I display in in the console (calling an object - e.g. `df` - is actually equivalent to calling `print(df)`), the output looks alright, but it could be improved. Some packages, such as knitr, have functions to create a nicer output. For instance, in markdown, so that it can be nicely rendered in markdown documents when copied:

    knitr::kable(df, format = "markdown")

    | Variable|Group |   CI| CI_low| CI_high|      p|
    |--------:|:-----|----:|------:|-------:|------:|
    |        1|A     | 0.95|  3.350|   4.230| 0.0010|
    |        3|A     | 0.95|  2.425|   5.310| 0.0456|
    |        5|A     | 0.95|  6.213|   7.123| 0.4500|
    |        3|B     | 0.95| 12.100|  13.500| 0.0042|
    |        1|B     | 0.95|  1.230|   3.610| 0.3400|

Or HTML, which again makes it look great in HTML files (such as this webpage you’re reading):

    knitr::kable(df, format = "html")

Variable | Group | CI | CI_low | CI_high | p
--- | --- | --- | --- | --- | ---
1 | A | 0.95 | 3.350 | 4.230 | 0.0010
3 | A | 0.95 | 2.425 | 5.310 | 0.0456
5 | A | 0.95 | 6.213 | 7.123 | 0.4500
3 | B | 0.95 | 12.100 | 13.500 | 0.0042
1 | B | 0.95 | 1.230 | 3.610 | 0.3400

## The insight workflow

The insight package also contains function to improve the “printing”, or rendering, of tables. Its design dissociates two separate and independent steps: formatting and exporting.

### Formatting

The purpose of formatting is to improve a given table, while still keeping it as a regular R data frame, so that it can be for instance further modified by the user.

    format_table(df)
    #>   Variable Group         95% CI     p
    #> 1     1.00     A [ 3.35,  4.23] 0.001
    #> 2     3.00     A [ 2.42,  5.31] 0.046
    #> 3     5.00     A [ 6.21,  7.12] 0.450
    #> 4     3.00     B [12.10, 13.50] 0.004
    #> 5     1.00     B [ 1.23,  3.61] 0.340

As you can see, `format_table()` modifies columns, turning number into characters (so that it has the same amount of digits), and detecting confidence intervals. This is usually combined with column-specific formatting functions, like `format_p()`:

    df %>%
      mutate(p = format_p(p, stars = TRUE)) %>%
      format_table()
    #>   Variable Group         95% CI           p
    #> 1     1.00     A [ 3.35,  4.23] p = 0.001**
    #> 2     3.00     A [ 2.42,  5.31] p = 0.046*
    #> 3     5.00     A [ 6.21,  7.12] p = 0.450
    #> 4     3.00     B [12.10, 13.50] p = 0.004**
    #> 5     1.00     B [ 1.23,  3.61] p = 0.340

### Exporting

The next step is exporting, which takes a data frame and renders it in a given format, so that it looks good in the console, or in markdown, HTML or latex.

For console output, we need to `cat()` the returned result to get nicely printed code:

    cat(export_table(df))
    #> Variable | Group |   CI | CI_low | CI_high |        p
    #> -----------------------------------------------------
    #>        1 |     A | 0.95 |   3.35 |    4.23 | 1.00e-03
    #>        3 |     A | 0.95 |   2.42 |    5.31 |     0.05
    #>        5 |     A | 0.95 |   6.21 |    7.12 |     0.45
    #>        3 |     B | 0.95 |  12.10 |   13.50 | 4.20e-03
    #>        1 |     B | 0.95 |   1.23 |    3.61 |     0.34

For markdown or HTML, simply modify the `format` argument to markdown (“md”)…

    export_table(df, format = "md")

Variable | Group | CI | CI_low | CI_high | p
--- | --- | --- | --- | --- | ---
1 | A | 0.95 | 3.35 | 4.23 | 1.00e-03
3 | A | 0.95 | 2.42 | 5.31 | 0.05
5 | A | 0.95 | 6.21 | 7.12 | 0.45
3 | B | 0.95 | 12.10 | 13.50 | 4.20e-03
1 | B | 0.95 | 1.23 | 3.61 | 0.34

…or HTML format.

    export_table(df, format = "html")

Variable | CI | CI_low | CI_high | p
--- | --- | --- | --- | ---
A
1 | 0.95 | 3.35 | 4.23 | 1.00e-03
3 | 0.95 | 2.42 | 5.31 | 0.05
5 | 0.95 | 6.21 | 7.12 | 0.45
B
3 | 0.95 | 12.10 | 13.50 | 4.20e-03
1 | 0.95 | 1.23 | 3.61 | 0.34

This can be combined with `format_table()`.

    df %>%
      format_table(ci_brackets = c("(", ")")) %>%
      export_table(format = "html")

Variable | 95% CI | p
--- | --- | ---
A
1.00 | ( 3.35, 4.23) | 0.001
3.00 | ( 2.42, 5.31) | 0.046
5.00 | ( 6.21, 7.12) | 0.450
B
3.00 | (12.10, 13.50) | 0.004
1.00 | ( 1.23, 3.61) | 0.340

TODO: What about display?