Spearman's rank correlation

Question

i'm writing a script that reads two .txt file in two vectors. After that I want to make a Spearman's rank correlation and plot the result. The first vectors value's length is 12-13 characters (e.g. 7.3445555667 or 10.3445555667) and the second vectors value's length is one character (e.g. 1 or 2). The code: ``` vector1 <- read.table ("D:...path.../mytext1.txt", header=FALSE) vector2 <- read.table ("D:...path.../mytext2.txt", header=FALSE) cor.coeff = cor(vector1 , vector2 , method = "spearman") cor.test(vector1 , vector2 , method = "spearman") plot(vector1.var, vector2.var) ``` The .txt files contain only numeric values. I'm getting two errors, the first in line 4 it's like " 'x' have to be a numeric vector" and the second error occurs in line 5 it's like "object vector 1.var couldn't be found" I also tried ``` plot(vector1, vector2) ``` instead of ``` plot(vector1.var, vector2.var) ``` But then there's an error like "Error in stripchart.default (x1,...) : invalid plot-method The impl…

Accepted Answer

I doubt `vector1` and `vector2` are vectors. Reading `?read.table` we note in the Value section:

Value:

```
    A data frame (‘data.frame’) containing a representation of the
    data in the file.
```

....

So even if your two text files contain just a single variable, the two objects read in will be data frames with a single component each.

Secondly, your data files don't contain headers so R will make up a variable name. I haven't tested this but IIRC your the variables in `vector1` and `vector2` will both be called `X1`. Do `head(vector1)` and the same on `vector2` (or `names(vector1)`) to see how your objects look in R.

I can see why you might think `vector1.var` might work, but you should realise that as far as R was concerned it was looking for an object named `vector1.var`. The `.` is just any other character in R object names. If you meant to use `.` as a subsetting or selection operator, then you need to read up on subsetting operators in R. These are `$` and `[` and `[[`. See for example the R Language Definition manual or the R manual.

I suspect you could just change your code to:

```
vector1 <- read.table ("D:...path.../mytext1.txt", header=FALSE)[, 1]
vector2 <- read.table ("D:...path.../mytext2.txt", header=FALSE)[, 1]
cor.coeff <- cor(vector1 , vector2 , method = "spearman")
cor.test(vector1 , vector2 , method = "spearman")
plot(vector1, vector2)
```

But I am supposing quite a bit about what is in your two text files...

Spearman's rank correlation

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