# Tables in the HTML format


```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(tidyverse)
```



# knitr

*knitr* package includes a handy *kable()* function that produces simple tables:

```{r}
data(mtcars)
knitr::kable( head(mtcars))
```

***********

# pander

*pander* package is a relatively simple to use package. It can produce well-formatted tables for the outputs of summary() function for the datasets and models:
```{r warning=FALSE}
library(pander)
pander( summary(mtcars[, 1:4]) )
```

```{r}
model <- lm( mpg ~ cyl, data=mtcars )    # a simple lenear regression
pander( summary(model) )  
```


***********

# DT

*DT* package can display matrices and data frames as tables and provides filtering and sorting. It is especially useful to display long tables that do not fit on a single page:

```{r}
DT::datatable(data=mtcars)
```


***********

# kableExtra 

*kableExtra* package extends functionality of the *kable* package.


```{r, warning=FALSE, message=FALSE}
library(kableExtra)
df <- mtcars[1:5, 1:6]

df %>%
  kbl() 
```
  
***

This package has a few themes:

- kable_paper("hover", full_width = F)
- kable_classic(full_width = F, html_font = "Cambria")
- kable_classic_2(full_width = F)
- kable_minimal()
- kable_material(c("striped", "hover"))
- kable_material_dark()

```{r}
df %>%
  kbl() %>%
  kable_classic()
```
  
***

## kable_styling

Function *kable_styling()* allows other ways to customize the output table:

```{r}
df %>%
  kbl() %>%
  kable_styling(bootstrap_options = c("striped", "hover", "condensed"))
```
  
***

*kable_styling()* includes the following options:

- *full_width* - TRUE or FALSE (default - TRUE)
- *position* - "left", "center", "right", "float_left", "float_right"
- *font_size* - a numeric value
- *fixed_thead* - T or F (option to fix the header row on top)


## Column_spec

This function can be used to format specific columns, e.g:
```{r}
df %>%
  kbl() %>%
  kable_minimal() %>%
  column_spec(1, bold = T) %>%
  column_spec(2, background="lightyellow")
```

  
***

We can also use a *conditional* formatting for the values in a column based on a value of another variable:
```{r}
df %>%
  kbl() %>%
  kable_minimal() %>%
  column_spec(1, bold = T) %>%
  column_spec(5, color=ifelse(df$hp==110, "red", "black"))
```


  
***


## Row_spec

Similar to column_spec, we can use *row_spec()* function to format rows:
```{r}
df %>%
  kbl() %>%
  kable_paper(full_width = F) %>%
  column_spec(1, bold = T) %>%
  row_spec(3, background="brown", color="white", bold = TRUE)
```

  
***

## Sparklines

We can include inline plots into this table. The following types of plots are available:

- spec_hist
- spec_boxplot
- spec_plot

First let's prepare the data:
```{r}
(mpg_list <- split(mtcars$mpg, mtcars$cyl))

```

Then we need to define a table with the desired number of rows and columns and give columns names:

```{r}
df_plot <- data.frame(cyl = c(4, 6, 8), 
                      mpg_box = "", 
                      mpg_hist = "",
                      min = unname(sapply(mpg_list, min)), 
                      max = unname(sapply(mpg_list, max)),
                      mean = unname(sapply(mpg_list, mean)))
```

Now we can add the plots into the first two columns:

```{r}
df_plot  %>%
  kbl(booktabs = TRUE) %>%
  kable_paper(full_width = FALSE) %>%
  column_spec(2, image = spec_boxplot(mpg_list)) %>%
  column_spec(3, image = spec_hist(mpg_list)) 
```

For more examples see [Create Awesome HTML Table with knitr::kable and kableExtra](https://cran.r-project.org/web/packages/kableExtra/vignettes/awesome_table_in_html.html)