I am trying to run Mann-Whiteney-U test with following code:

package main
import (
    "fmt"
    "stats" 
)
func main() {
    e, _ = MannWhitneyUTest([]float64{1, 2, 3, 4, 5}, 
                            []float64{1, 2, 3, 5, 6}, 
                            0) 
    fmt.Println("Mann-WhitneyUTest: ", e)
}

However, this gives me this error:

$ go run mainstats2.go 
mainstats2.go:5:2: cannot find package "stats" in any of:
        /usr/local/go/src/stats (from $GOROOT)
        /home/iuser/go/src/stats (from $GOPATH)

I have following stats packages installed:

$ go list all | grep stats
github.com/montanaflynn/stats
github.com/montanaflynn/stats/examples
golang.org/x/perf/internal/stats
golang.org/x/perf/vendor/github.com/aclements/go-moremath/stats
golang.org/x/perf/vendor/google.golang.org/grpc/stats

I need stats package golang.org/x/perf/ which I had installed by command: go get golang.org/x/perf/internal/stats

I believe this package is already there in go installation and was not needed to be installed separately.

How do I solve this problem? Thanks for your help.

The error occurs because your import path is incorrect, it should be:

import (
    "fmt"
    "golang.org/x/perf/internal/stats" 
)

But even though import path issue is fixed, you'll get another error for trying to use internal package.

stats.go:4:5: use of internal package golang.org/x/perf/internal/stats not allowed

I suggest try to find another alternative library.

EDIT #1:

If you insist, there is a workaround. Try to copy the $GOPATH/src/golang.org/x/perf/internal/stats folder directly into your project, then import it. It worked, please see screenshot below.

EDIT 2:

I have copied the folder to ~/go/src/stats. It is still not working. What should I put for import. Currently it is just "stats"

I think you are doing it wrong. First, you need to create what-so-called project, it's a folder placed inside $GOPATH/src.

For example in image below I created a project called my-example-app, placed under $GOPATH/src. So the full path of the project will be $GOPATH/src/my-example-app.

Inside my project, I created main.go file. This file contains the code (I copied from yours).

Also, I copied the $GOPATH/src/golang.org/x/perf/internal/stats folder into my project, so the stats folder will be on the same level with my main.go.

The import of stats folder need to be happen relative to the project name, so the correct import path would be:

import "my-example-app/stats"

Here is content of my main.go (copied from yours with some syntax error fix addition).

package main

import (
    "fmt"
    "my-example-app/stats"
)

func main() {
    e, _ := stats.MannWhitneyUTest([]float64{1, 2, 3, 4, 5},
        []float64{1, 2, 3, 5, 6},
        0)
    fmt.Println("Mann-WhitneyUTest: ", e)
}