Biometric Measurements on Douglas Fir
Two students at Seattle Community College made biometric measurements on 25 Douglas fir (Pseudotsuga menziesii) trees in the lowlands of western Washington. The variables recorded in the DougFirBiometrics.csv file are a unique tree identifier (
tree), the observer’s name (
observer; either “Ingrid” or “Dylan”), the circumference at breast height (meters;
circ), the height to the eye of the observer (meters;
eyeht), the horizontal distance between observer and tree (meters;
horizdist), the angle between observer and top of tree (degrees;
angle), and the estimated height of tree (meters;
height) using right-angle trigonometry. Read these data into an R object called
df and examine the structure and a few lines of the data.frame. Answer the following questions.
- Show all estimated tree heights.
- Show all measurements for all trees measured by “Ingrid.” [HINT: filter the original data.frame.]
- Show all estimated tree heights for all trees measured by “Dylan.” [HINT: filter the original data.frame.]
- Show all measurements for tree heights less than 10 m. [HINT: filter the original data.frame.]
- Show all measurements for tree heights greater than 10 m and circumference less than 1 m. [HINT: filter the original data.frame.]
- Show all measurements made on the third tree. [Do not do this manually; use R code.]
- Show the estimated tree height for the fifth tree.