loop through data instead of indexing in R - r

Question

I am trying to convert my data into a html document using Rmarkdown, and I am currently relying on conversion to vectors and indexing to solve my problem.
Although my sample data has 4 observations, my actual datasets has over 30 records, so indexing seems cumbersome and unnatural.
Is there a better way to pull out each of these elements in sequence? Any suggestions would be great.
--
title: "Rmarkdown report"
output: html_document
---
```{r echo = FALSE}
mydata <- data.frame(First = c("John", "Hui", "Jared"), Second = c("Smith", "Chang", "Jzu"), Sport = c("Football","Soccer","Ballet"), Age = c("12", "13", "12"), submission = c("Microbes may be the friends of future colonists living off the land on the moon, Mars or elsewhere in the solar system and aiming to establish self-sufficient homes. Space colonists, like people on Earth, will need what are known as rare earth elements, which are critical to modern technologies. These 17 elements, with daunting names like yttrium, lanthanum, neodymium and gadolinium, are sparsely distributed in the Earths crust. Without the rare earths, we wouldn’t have certain lasers, metallic alloys and powerful magnets that are used in cellphones and electric cars. But mining them on Earth today is an arduous process. It requires crushing tons of ore and then extracting smidgens of these metals using chemicals that leave behind rivers of toxic waste water.",
"Experiments conducted aboard the International Space Station show that a potentially cleaner, more efficient method could work on other worlds: let bacteria do the messy work of separating rare earth elements from rock. The idea is the biology is essentially catalyzing a reaction that would occur very slowly without the biology, said Charles S. Cockell, a professor of astrobiology at the University of Edinburgh.
On Earth, such biomining techniques are already used to produce 10 to 20 percent of the world’s copper and also at some gold mines; scientists have identified microbes that help leach rare earth elements out of rocks.",
"Experiments conducted aboard the International Space Station show that a potentially cleaner, more efficient method could work on other worlds: let bacteria do the messy work of separating rare earth elements from rock. The idea is the biology is essentially catalyzing a reaction that would occur very slowly without the biology, said Charles S. Cockell, a professor of astrobiology at the University of Edinburgh.
On Earth, such biomining techniques are already used to produce 10 to 20 percent of the world’s copper and also at some gold mines; scientists have identified microbes that help leach rare earth elements out of rocks."))
first<- as.vector(mydata$First)
sec <- as.vector(mydata$Second)
age <- as.vector(mydata$Age)
submission <- as.vector(mydata$submission)
```
##
**First:** `r first[1]`   **Second:** `r sec[1]` <br>
**Age:** `r age[1]`
**submission** <br>
`r submission[1]`
***
**First:** `r first[2]`   **Second:** `r sec[2]` <br>
**Age:** `r age[2]`
**submission** <br>
`r submission[2]`

Answer 1

Here's a way to iterate over all rows
---
title: "Rmarkdown report"
output: html_document
---
```{r echo = FALSE}
# using data from above
# mydata <- data.frame(...)
# Define template (using column names from data.frame)
template <- "**First:** `r First`   **Second:** `r Second` <br>
**Age:** `r Age`
**submission** <br>
`r submission`"
# Now process the template for each row of the data.frame
src <- lapply(1:nrow(mydata), function(i) {
knitr::knit_child(text=template, envir=mydata[i, ], quiet=TRUE)
})
```
# Print result to document
`r knitr::knit_child(text=unlist(src))`
Here we use knit_child to take a template string and then use that for each row of the data.frame. I used a trick here to pass in the row of the data.frame as an environment so the template can see all the columns as variables so we don't need to create the vector versions of all the data.frame columns.

Answer 2

If we need to create objects in the global env, subset the columns of data into a list, rename it and use list2env
nm1 <- c('First', 'Second', 'Age', 'submission')
nm2 <- c('first', 'sec', 'age', submission')
list2env(setNames(unclass(mydata[nm1]), nm2), .GlobalEnv)

Answer 3

This is the answer I gave to your previous question:
You can use cat to add the HTML code to an R markdown chunk in order to loop through your data.
Important
You have to add results = "asis" to {r}
Here is the loop:
{r results="asis", echo = FALSE}
i = 1
NR_OF_ROWS <-
nrow(data) # number of rows that the loop will go through
while (i <= NR_OF_ROWS) {
cat("\n **First:** ", data[i, 1], "  **Last:** ", data[i, 2], "<br> \n")
cat("\n **Age:** ", data[i, 3], "  **Sport:** ", data[i, 4], "<br> \n")
cat("\n **submission** ", data[i, 5], "<br> \n")
# cat("\n <br> \n") extra space between entries
cat("\n *** \n") line between entries
i = i + 1
}
Here is the result: