Sorting 2d slice [][]string (slice of slices)

[Martin Johnson]

Hi, 

I'm connecting to an online API at http://seranking.com/api.html to obtain data for a client report

that ultimately ends up in Excel. 

The example nested JSON response is:

[ {"id":"1","keywords":[{"id":"1","positions":[{"date":"2015-09-03", "change":"1","pos":"1"},...]]}, .... ]

Once the JSON is successfully unmarshaled I'm then writing the data to a CSV file using "encoding/csv". 

The CSV output of my slice of slices (csvSlice[][]) looks like this:

keyword phrase one,http://www.example.co.uk/landing/example1,90
keyword phrase two,http://www.example.co.uk/landing/example2,6
keyword phrase three,http://www.example.co.uk/landing/example3,9
keyword phrase four,http://www.example.co.uk/landing/example4,78
...

I'd like to sort the slices prior to creating the csv file so the above would output like the below (sorted by last string, which is the position in the Google)

keyword phrase two,http://www.example.co.uk/landing/example2,6
keyword phrase three,http://www.example.co.uk/landing/example3,9
keyword phrase four,http://www.example.co.uk/landing/example4,78
keyword phrase one,http://www.example.co.uk/landing/example1,90
...

Currently I'm only able to sort the slice in the slice, for example I can do this:

6, http://www.example.co.uk/landing/example2, keyword phrase two
...

All the basic examples I can find relate to sorting a slice and not a slice of slices. 

people := []Person{

{"Bob", 31},

{"John", 42},

{"Michael", 17},

{"Jenny", 26},

}

Can anyone point me in the right direction? 

Thank you

Martin

[Volker Dobler]

Am Dienstag, 8. September 2015 02:17:08 UTC+2 schrieb Martin Johnson:

> All the basic examples I can find relate to sorting a slice and not a slice of slices.

These examples actually _do_ show how to sort a slice of slices:

It does not matter what the slice you want to sort consists of: The slice

you want to sort can be made of ints, structs, slices, maps or even 

slices of structs of ... You always sort a slice of 'records'.

All need to understand to adopt e.g. the example given in the sort package

is, that the Less method compares not the whole element of the slice (the

whole record) to sort, but just a certain sub-key, a certain aspect of the

record (here Age). Your records are slices and the you want to sort your

records on the third value of your records.

So your Less method will look something like.

   Less(i, j, int) bool { return a[i][2] < a[j][2] } 

V.

[Giulio Iotti]

Does this example clarify a bit? https://play.golang.org/p/2uvmO_z8QA

-- 

Giulio Iotti 

[Martin Johnson]

Hi again, 

Thank you both for the explanations and code examples! I have now successfully sorted the 

slices of slices. 

Kind regards

Martin

[Gyu-Ho Lee]

I have code for this kind of problem, given that the slice is of string slice.

https://github.com/gyuho/learn/tree/master/doc/go_sort_algorithm#sort-table

Thanks,

[Martin Johnson]

Gyu-Ho Lee, 

Thank you for the additional code! Golang-nuts is turning out to be an incredible resource. 

Kind regards

Martin