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R Data Frames
Data Frames
Data frames are formatted as a table.
Data frames can have different types of data within them. Although the first column may be a character, the second and third may be numeric or logical. However, each column should contain the same type of data.
Use the data.frame() function to create a data frame:
Example
Data_Frame <- data.frame (
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
# Print the data frame
Data_Frame
Summarize the Data
Use the summary() function to summarize data from the Database:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
Data_Frame
summary(Data_Frame)
You will learn more about the function of summary() in the mathematical component of the R lesson.
Access Items
We can use individual brackets [ ], double brackets [[ ]] or $ to access columns of data:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
Data_Frame[1]
Data_Frame[["Training"]]
Data_Frame$Training
Add Rows
Use the rbind() function to add new lines to the Data Frame:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
# Add a new row
New_row_DF <- rbind(Data_Frame, c("Strength", 110, 110))
# Print the new row
New_row_DF
Add Columns
Use the cbind() function to add new columns to the Data Frame:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
# Add a new column
New_col_DF <- cbind(Data_Frame, Steps = c(1000, 6000, 2000))
# Print the new column
New_col_DF
Remove Rows and Columns
Use the function c() to delete rows and columns in the Data Frame:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
# Remove the first row and column
Data_Frame_New <- Data_Frame[-c(1), -c(1)]
# Print the new data frame
Data_Frame_New
Amount of Rows and Columns
Use the dim() function to find the number of rows and columns in Data Frames:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
dim(Data_Frame)
You can also use the ncol() function to find the number of columns and then nrow() to get the number of rows:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
ncol(Data_Frame)
nrow(Data_Frame)
Data Frame Length
Use the length() function to get the number of columns in Data Frames (similar to ncol()):
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
length(Data_Frame)
Combining Data Frames
Use the rbind() function to merge two or more data frames into R directly:
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
Data_Frame2 <- data.frame (
Training = c("Stamina", "Stamina", "Strength"),
Pulse = c(140, 150, 160),
Duration = c(30, 30, 20)
)
New_Data_Frame <- rbind(Data_Frame1, Data_Frame2)
New_Data_Frame
Also use the cbind() function to merge two or more data frames into R
Example
Training = c("Strength", "Stamina", "Other"),
Pulse = c(100, 150, 120),
Duration = c(60, 30, 45)
)
Data_Frame4 <- data.frame (
Steps = c(3000, 6000, 2000),
Calories = c(300, 400, 300)
)
New_Data_Frame1 <- cbind(Data_Frame3, Data_Frame4)
New_Data_Frame1