How to search a data frame by x and y cords in R

[ProPatto16]

Hi Readers,

I seem to have hit an elementary snag while fiddling in R...

i have a 5x5m surface interpolated at intervals of 0.01... giving 250,000 squares in my grid. i have roughly 20-30 xy cords where i want to retrieve the z value out of the data frame. does anyone know how to search an x y z data frame using the x and y cord?okay so I've figured it out using subset...

but the problem is out of the 250000 rows in the dataframe i want my 20-30 extracted. but the x and y values for the points i want extracted are stored as vectors.. so i need to figure out how to apply subset using vectors.

by doing

row<-subset(dataframe, x==1.05 & y==0.25)
that retrieves the correct row with those x and y values...

but say i have vectors of equal length for the x and y values i want stored in xt and yt then doing this

row<-subset(dataframe, x==xt & y==yt)

results in

[1] x y Height
<0 rows> (or 0-length row.names)

Is there a way i can apply subsetting using vectors for the x and y values i want to extract?thanks

 

[KataKoniK]

Hello,

As a scientist familiar with R, I can offer some advice on how to solve your problem. It seems like you have the right idea with using the subset function, but instead of using the "==" operator, you should use the "%in%" operator. This will allow you to specify multiple values for x and y, instead of just one as in your example.

So your code would look something like this:

row <- subset(dataframe, x %in% xt & y %in% yt)

This should result in the extraction of the rows with the specified x and y values. Let me know if this works for you or if you need any further assistance.