ASMAS SS2024 - Exercise 2

Author

Peter von Rohr

Published

February 26, 2024

Problem 1: Reading Data

The first step of a data analysis in R is to read the data. This can be done in different ways which are described below.

Direct Assignment

As done in Exercise 1, we have assigned the data directly to different R-objects. To recap, this was done with

vec_width <- c(82,65,76,80,78,70,72,70,65,73)
vec_height <- c(185,168,168,193,180,181,182,169,165,170)

Reading Files

  • From local storage: read data from local file
  • From website: specify link directly

Different Formats

  • Excel: An excel file has to be downloaded first and can then be imported.
# download first
s_wh_data <- "https://charlotte-ngs.github.io/asmasss2024/data/asm_width_height.xlsx"
s_down_dir <- tempdir()
s_dest_file <- file.path(s_down_dir, basename(s_wh_data))
download.file(url = s_wh_data, destfile = s_dest_file)
# read from local file
tbl_wh <- readxl::read_excel(s_dest_file)
# delete downloaded file
unlink(s_dest_file)
# show table read from xlsx
tbl_wh
# A tibble: 10 × 2
   Width Height
   <dbl>  <dbl>
 1    82    185
 2    65    168
 3    76    168
 4    80    193
 5    78    180
 6    70    181
 7    72    182
 8    70    169
 9    65    165
10    73    170
  • CSV
s_wh_data <- "https://charlotte-ngs.github.io/asmasss2024/data/asm_width_height.csv"
tbl_wh <- readr::read_delim(s_wh_data, delim = ",")
Rows: 10 Columns: 2
── Column specification ────────────────────────────────────────────────────────
Delimiter: ","
dbl (2): Width, Height

ℹ Use `spec()` to retrieve the full column specification for this data.
ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
tbl_wh
# A tibble: 10 × 2
   Width Height
   <dbl>  <dbl>
 1    82    185
 2    65    168
 3    76    168
 4    80    193
 5    78    180
 6    70    181
 7    72    182
 8    70    169
 9    65    165
10    73    170

The downloaded data can be summarized using the function summary().

summary(tbl_wh)
     Width          Height     
 Min.   :65.0   Min.   :165.0  
 1st Qu.:70.0   1st Qu.:168.2  
 Median :72.5   Median :175.0  
 Mean   :73.1   Mean   :176.1  
 3rd Qu.:77.5   3rd Qu.:181.8  
 Max.   :82.0   Max.   :193.0

Problem 2: Download Beef-Cattle Data

There is a dataset on Breast Circumference and Body Weight for beef cattle animals available in two different formats.

  1. Excel: https://charlotte-ngs.github.io/asmasss2024/data/asm_bw_bc_reg.xlsx
  2. CSV: https://charlotte-ngs.github.io/asmasss2024/data/asm_bw_bc_reg.csv

Tasks

  • Read the data from both formats
  • Provide summary statistics of the variables Breast Circumference and Body Weight
  • Plot Breast Circumference on the x-axis and Body Weight on the y-axis

Solutions

  • Read the data Start by reading from Excel workbook

Read data from CSV-file

  • Summary statistics for Breast Circumference and Body Weight
  • Plot