68 lines
1.9 KiB
Markdown
68 lines
1.9 KiB
Markdown
---
|
|
title: Data Frames
|
|
---
|
|
|
|
## Data Frames
|
|
|
|
A data frame is an object in R.
|
|
|
|
### Creating a Data Frame
|
|
|
|
You can create a data frame by combining vectors of the same length and using the function `data.frame`.
|
|
```r
|
|
a <- c(1 ,2, 3, 4, 5) #vector a
|
|
b <- c("H", "E", "L", "L", "O") #vector b
|
|
c <- c(TRUE, FALSE, FALSE, TRUE, FALSE) #vector c
|
|
|
|
df <- data.frame(a, b, c)
|
|
```
|
|
**NOTE**: You can also import data from a various data file such as a csv file to a data frame. See `Additional Resources` below for help with that.
|
|
|
|
### Adding Columns
|
|
|
|
To add a new column you can do `df$new_column_name`
|
|
|
|
#### Example
|
|
```r
|
|
df$product <- 2 * df[,1]
|
|
```
|
|
|
|
You can alternatively have a vector with them same amount of elements as a column in `df` as use the function `cbind` to combine it to `df`.
|
|
```r
|
|
product <- c(2, 4, 6, 8, 10)
|
|
df <- cbind(df, product)
|
|
```
|
|
Both ways will output the following table:
|
|
```
|
|
a b c product
|
|
1 1 H TRUE 2
|
|
2 2 E FALSE 4
|
|
3 3 L FALSE 6
|
|
4 4 L TRUE 8
|
|
5 5 O FALSE 10
|
|
```
|
|
|
|
### Removing Columns or Rows
|
|
|
|
You can remove a column or row by using `$` to specify a specific column name and making it `NULL`.
|
|
```r
|
|
df$b <- NULL #column b in df is deleted
|
|
```
|
|
Alternatively you can delete a specific row by using `df[row,]` or delete a specific row by using `df[,column]`.
|
|
|
|
#### Example
|
|
```r
|
|
df[1,] <- NULL #Deletes first row in df
|
|
|
|
df[,2] <- NULL #Deletes second column in df
|
|
```
|
|
### Sources
|
|
1. [DataMentor](https://www.datamentor.io/r-programming/data-frame/)
|
|
2. [ListenData](https://www.listendata.com/2015/06/r-keep-drop-columns-from-data-frame.html)
|
|
3. [PROGRAMMINGR](http://www.programmingr.com/examples/r-dataframe/add-delete-rows/)
|
|
|
|
### Additional Resources
|
|
1. [Data Frame Manipulation](http://www.cookbook-r.com/Manipulating_data/)
|
|
2. [Working with data in RStudio](http://paldhous.github.io/ucb/2016/dataviz/week7.html)
|
|
3. [Importing Data](https://www.datacamp.com/community/tutorials/r-data-import-tutorial)
|