A trip to the grocery wasn't so bad!

I saw an assassin bug. It was huge!

This is Arilus cristatus or commonly known as the Wheel Bug (Appropriately named!)

Don't try to handle them, they have a painful bite from what I hear. Good predators for garden pest.

How to use information in one data frame to subset data in another (R Code)

Just got into grad school! So finally settled in and ready to write more blog posts.

Here is an hour project that I worked on. My friend has a huge data file on a dung beetle population and recorded many important information daily. It looks something like this:

Figure 1: Fake Randomly Generated Data

 So he comes up to me and say,

Him: "I want to average the 5 different variables"
Me: "Okay, like weekly? So like every 8 rows?"
Him: "Oh no, I have a data file of the dates that I want to serve as start-date and end-date.
So the duration of the start-date and end date will be different"

He then opens up another CSV file

Figure 2: Fake  Dates

I want the data averaged from 1/1/1989 to 1/4/1989, 1/4/1989 to 1/5/1989, etc.

And then I threw a string of obscenities at him for making it harder. So basically, I run a for-loop (don't judge me).

Steps (Code is below: NOTE THAT YOU MUST CHANGE CERTAIN THINGS FOR YOUR OWN SPECIFIC NEEDS)

1) I uploaded the two different files into my R workstation. One will be the record (Figure 2) and the other will be the main data. My friend had some other variables in his record file and I just wanted the dates so I created a new variable, x.

2) I created an empty list so I can put newly averaged data into the list.

3) I ran a for-loop on the record data (x).

4) I use the "match" function to find the index of the main data and use that to subset the portion of the maindata (from the start-date to the end-date)

5) I then average the columns

6) Because the averages are in a column form, I transpose it

7) I then column bind the start date, end date, and the averages

8) I put this into the list

REPEAT

9) After I finished, I turn the list into a data.frame