CODEWITHSUNDEEP
rcorrelation
cjthedj55
cjthedj55

Reputation: 33

how to correlate 2 variables when X > 1

I have a data set and want to run a correlation between X and Y. However, I only want to look at X values that are greater than 1. 

cor(Data$X, Data$Y, use = "complete.obs")

What argument do I add to run a correlation between X and Y only for the X values that are greater than 1?

Upvotes: 0

Views: 55

Answers (1)

MDK
MDK

Reputation: 300

You can subset using the [ operator.

Try this:

# Generate Example Data
Data <- data.frame(X = seq(-5, 10, 1),
                   Y = sample(1:100, 16))

with(data = Data[Data$X > 1, ], cor(X, Y, use = "complete.obs"))

[ lets us specify rows and columns in the style my.data.frame[rows, columns]. Here we are specifying that we want only rows where X > 1, but all columns. We could also do the following to ask for each column individually by name:

cor(Data[Data$X > 1, "X"], Data[Data$X > 1, "Y"], use = "complete.obs"))

Or even the following to subset the column vectors:

cor(Data$X[Data$X > 1], Data$Y[Data$X > 1], use = "complete.obs"))

Of course, these are only to illustrate the flexibility. It's best to subset the whole data set once to avoid discrepancies.

Upvotes: 2

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