---
title: "Dataset (data frame) manipulation API for the tech.ml.dataset library"
output:
md_document:
variant: gfm
---
```{r setup, include=FALSE}
find_nrepl_port_up <- function() {
wd <- getwd()
while(wd != dirname(wd)) {
f <- paste0(wd,"/.nrepl-port")
if(file.exists(f)) return(paste0("@",f))
wd <- dirname(wd)
f <- NULL
}
}
port_file <- find_nrepl_port_up()
if(is.null(port_file)) stop("nREPL port not found")
library(knitr)
knitr_one_string <- knitr:::one_string
nrepl_cmd <- "rep"
opts_chunk$set(comment=NA, highlight=TRUE)
knit_engines$set(clojure = function(options) {
rep_params <- if(isTRUE(options$stdout_only)) {
"--print 'out,1,%{out}' --print 'value,1,' -p"
} else {
"-p"
}
code <- paste(rep_params, port_file, shQuote(knitr_one_string(options$code)))
out <- if (options$eval) {
if (options$message) message('running: ', nrepl_cmd, ' ', code)
tryCatch(
system2(nrepl_cmd, code, stdout = TRUE, stderr = TRUE, env = options$engine.env),
error = function(e) {
if (!options$error) stop(e)
paste('Error in running command', nrepl_cmd)
}
)
} else ''
if (!options$error && !is.null(attr(out, 'status'))) stop(knitr_one_string(out))
engine_output(options, options$code, out)})
```
[](https://clojars.org/scicloj/tablecloth)
[](https://travis-ci.org/github/scicloj/tablecloth)
[](https://clojurians.zulipchat.com/#narrow/stream/236259-tech.2Eml.2Edataset.2Edev/topic/api)
## Versions
### tech.ml.dataset 7.x (master branch)
[](https://clojars.org/scicloj/tablecloth)
### tech.ml.dataset 4.x (4.0 branch)
`[scicloj/tablecloth "4.04"]`
## Introduction
[tech.ml.dataset](https://github.com/techascent/tech.ml.dataset) is a great and fast library which brings columnar dataset to the Clojure. Chris Nuernberger has been working on this library for last year as a part of bigger `tech.ml` stack.
I've started to test the library and help to fix uncovered bugs. My main goal was to compare functionalities with the other standards from other platforms. I focused on R solutions: [dplyr](https://dplyr.tidyverse.org/), [tidyr](https://tidyr.tidyverse.org/) and [data.table](https://rdatatable.gitlab.io/data.table/).
During conversions of the examples I've come up how to reorganized existing `tech.ml.dataset` functions into simple to use API. The main goals were:
* Focus on dataset manipulation functionality, leaving other parts of `tech.ml` like pipelines, datatypes, readers, ML, etc.
* Single entry point for common operations - one function dispatching on given arguments.
* `group-by` results with special kind of dataset - a dataset containing subsets created after grouping as a column.
* Most operations recognize regular dataset and grouped dataset and process data accordingly.
* One function form to enable thread-first on dataset.
Important! This library is not the replacement of `tech.ml.dataset` nor a separate library. It should be considered as a addition on the top of `tech.ml.dataset`.
If you want to know more about `tech.ml.dataset` and `dtype-next` please refer their documentation:
* [tech.ml.dataset walkthrough](https://techascent.github.io/tech.ml.dataset/walkthrough.html)
* [dtype-next overview](https://cnuernber.github.io/dtype-next/overview.html)
* [dtype-next cheatsheet](https://cnuernber.github.io/dtype-next/cheatsheet.html)
Join the discussion on [Zulip](https://clojurians.zulipchat.com/#narrow/stream/236259-tech.2Eml.2Edataset.2Edev/topic/api)
## Documentation
Please refer [detailed documentation with examples](https://scicloj.github.io/tablecloth/index.html)
## Usage example
```{clojure results="hide"}
(require '[tablecloth.api :as tc])
```
```{clojure results="asis"}
(-> "https://raw.githubusercontent.com/techascent/tech.ml.dataset/master/test/data/stocks.csv"
(tc/dataset {:key-fn keyword})
(tc/group-by (fn [row]
{:symbol (:symbol row)
:year (tech.v3.datatype.datetime/long-temporal-field :years (:date row))}))
(tc/aggregate #(tech.v3.datatype.functional/mean (% :price)))
(tc/order-by [:symbol :year])
(tc/head 10))
```
## Contributing
`Tablecloth` is open for contribution. The best way to start is discussion on [Zulip](https://clojurians.zulipchat.com/#narrow/stream/236259-tech.2Eml.2Edataset.2Edev/topic/api).
### Development tools for documentation
Documentation is written in RMarkdown, that means that you need R to create html/md/pdf files.
Documentation contains around 600 code snippets which are run during build. There are two files:
* `README.Rmd`
* `docs/index.Rmd`
Prepare following software:
1. Install [R](https://www.r-project.org/)
2. Install [rep](https://github.com/eraserhd/rep), nRepl client
3. Install `pandoc`
4. Run nRepl
5. Run R and install R packages: `install.packages(c("rmarkdown","knitr"), dependencies=T)`
6. Load rmarkdown: `library(rmarkdown)`
7. Render readme: `render("README.Rmd","md_document")`
8. Render documentation: `render("docs/index.Rmd","all")`
### API file generation
`tablecloth.api` namespace is generated out of `api-template`, please run it before making documentation
```{clojure eval=FALSE}
(exporter/write-api! 'tablecloth.api.api-template
'tablecloth.api
"src/tablecloth/api.clj"
'[group-by drop concat rand-nth first last shuffle])
```
### Guideline
1. Before commiting changes please perform tests. I ususally do: `lein do clean, check, test` and build documentation as described above (which also tests whole library).
2. Keep API as simple as possible:
- first argument should be a dataset
- if parametrizations is complex, last argument should accept a map with not obligatory function arguments
- avoid variadic associative destructuring for function arguments
- usually function should working on grouped dataset as well, accept `parallel?` argument then (if applied).
3. Follow `potemkin` pattern and import functions to the API namespace using `tech.v3.datatype.export-symbols/export-symbols` function
4. Functions which are composed out of API function to cover specific case(s) should go to `tablecloth.utils` namespace.
5. Always update `README.Rmd`, `CHANGELOG.md`, `docs/index.Rmd`, tests and function docs are highly welcomed
6. Always discuss changes and PRs first
## TODO
* tests
* tutorials
## New experimental dev workflow
In this branch, we develop a new proposed dev workflow for Tablecloth:
- namespace-as-a-notebook documentation using [Kindly](https://scicloj.github.io/kindly) and [Clay](https://scicloj.github.io/clay)
- testing the documentation using [note-to-test](https://github.com/scicloj/note-to-test) - coming soon
### Relevant files
- [notebooks/draft.clj](notebooks/draft.clj) - the tutorial as a Kindly notebook (developed with Clay)
- [dev/conversion.clj](dev/conversion.clj) - the script used to generate the notebook from the original `Rmarkdown` tutorial (up to a few additional manual edits)
- [docs/draft.html](docs/draft.html) - the tutorial rendered using Clay and [Quarto](https://quarto.org/)
### Actions
- to render the notebook using Clay (assuming you have the Quarto CLI [installed](https://quarto.org/docs/get-started/)):
```clj
(require '[scicloj.clay.v2.api :as clay])
(clay/make! {:format [:quarto :html]
:source-path "notebooks/draft.clj"})
```
## Licence
Copyright (c) 2020 Scicloj
The MIT Licence
