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