How To Filter Data D3

Mathematics

Go the maximum value of a column chosen `value`

d3.max(data, office(d) { return +d.value; })])

Go the minimum value of a column called `value`

d3.min(data, function(d) { return +d.value; })])

Object and Arrays

JavaScript `objects` are containers for named values called properties or methods. We can call whatsoever element of the object with its proper noun:

var myObject = {proper noun:"Nicolas", sex:"Male", historic period:34} myObject.proper noun myObject["proper name"]

Create an `array` of five numbers

An array is a special variable, which can hold more than i value at a time. Arrays use numbered indexes.

var myArray = [12, 34, 23, 12, 89]

Access the outset chemical element in the array.

myArray[0]

Admission the terminal chemical element in the array.

myArray[myArray.length - 1]

Remove final chemical element of the array. Add together a new element a the stop.

myArray.pop() myArray.push(45)

What is the index of the element '34' in the assortment?.

myArray.indexOf(34)

Remove elements that are provided in a 2d array:

var myArray = ['a', 'b', 'c', 'd', 'e', 'f', 'g']; var toRemove = ['b', 'c', 'm']; filteredArray = myArray.filter( office( el ) {   return !toRemove.includes( el ); } );

Proceed only elements that are provided in a 2nd array:

var myArray = ['a', 'b', 'c', 'd', 'e', 'f', 'g']; var tokeep = ['b', 'c', 'g', 'o', 'z']; filteredArray = myArray.filter( function( el ) {   return tokeep.includes( el ); } );

Note

: an array can be composed by several objects!

Filtering

Go on rows where the variable `name` is `toto`

information.filter(part(d){ return d.name == "toto" })

Go along rows where the variable `proper noun` is different from `toto`

data.filter(function(d){ render d.proper name != "toto" })

Keep rows where the variable `proper noun` is `toto` OR `tutu`

data.filter(role(d){ return  (d.name == "toto" || d.proper noun == "tutu") })

Go on rows where the variable `name` has a value included in the list `tokeep`

tokeep = ["option1", "option2", "option3"] data.filter(part(d,i){ return tokeep.indexOf(d.name) >= 0 })

Go on the 10 start rows

data.filter(function(d,i){ return i<10 })

color points using `ifelse` statement

.style("fill", function(d){ if(d.ten<140){render "orange"} else {render "blue"}})

Sorting

Sorting on 1 numeric column called `value`. Use `+` instead of `-` for reverse society.

data.sort(function(a,b) { return +a.value - +b.value })

Sorting alphabetically on 1 categoric column called `name`. Use `descending` for reverse order.

data.sort(function (a,b) {return d3.ascending(a.name, b.proper name);});

Sorting alphabetically on 2 categoric columns called `name1` and `name2`.

data.sort(office(a,b) { return d3.ascending(a.name1, b.name1) ||  d3.ascending(a.name1, b.name2) } )

Sorting on one categoric columns chosen `name1` and then on 1 numeric chosen `value`.

data.sort(part(a,b) { return d3.ascending(a.name1, b.name1) ||  (a.value - b.value) } )

Sorting on ane categoric columns chosen `name1` according to the order provided in the variable `targetOrder`.

data.sort(function(a,b) {     return targetOrder.indexOf( a.name1 ) > targetOrder.indexOf( b.name1 ); });

Nesting

Sorting on one numeric column called `value`. Utilise `+` instead of `-` for reverse social club.

data.sort(office(a,b) { return +a.value - +b.value })

Sorting alphabetically on 1 categoric column called `name`. Use `descending` for contrary guild.

data.sort(function (a,b) {return d3.ascending(a.name, b.name);});

Grouping

Get a list of unique entries of a cavalcade called `name`

var allGroup = d3.map(data, function(d){return(d.name)}).keys()

Loop

A `for` loop from one to ten:

var i for (i = 0; i < ten; i++) {   console.log(i) }

A `for` loop for all the elements of a list: (Annotation that it returns 0, 1, two, not a, b, c)

var allGroup = ["a", "b", "c"] for (i in allGroup){   console.log(i) }

A `while` loop to count from 0 to 10

while (i < 10) {   console.log(i)   i++; }

Reshape

It is a mutual task in data science to swap betwixt wide (or untidy) format to long (or tidy) format. In R, there is a parcel called tidyr that is entirely dedicated to it. It is definitely doable in Javascript using the lawmaking snippets below. In example you lot're not familiar with this concept, hither is a description of what these formats are:

Annotation: information technology is strongly advised to perform these data wrangling steps out of your javascript to save loading fourth dimension of your dataviz

Going from `broad to long` format.

d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/chief/DATA/data_correlogram.csv", function(data) {    // Going from wide to long format   var data_long = [];   data.forEach(office(d) {     var ten = d[""];     delete d[""];     for (prop in d) {       var y = prop,         value = d[prop];       data_long.push({         ten: 10,         y: y,         value: +value       });     }   });    // Bear witness result   panel.log(data_long)

Going from `long to broad` format.

d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/Data/information.csv", part(information) {   //todo })

Stack

Stacking information is a common practice in dataviz, notably for barcharts and surface area charts. Stacking applies when a dataset is composed by groups (like species) and subgroups like soil status. Stacking is possible thanks to the d3.stack() function, which is function of the d3-shape module. Here is an analogy of what happens when you read data from .csv format and stack it.

Stacking from `.csv` format

d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/chief/DATA/data_stacked.csv", function(data) {    // Have a look to the data   panel.log(data)    // Listing of subgroups = header of the csv files = soil status here   var subgroups = data.columns.slice(1)    // List of groups = species here = value of the first cavalcade called group   var groups = d3.map(information, function(d){return(d.grouping)}).keys()    //stack the data? --> stack per subgroup   var stackedData = d3.stack()     .keys(subgroups)     (data)    // Have a expect to the stacked information   console.log(stackedData)    // Get the stacked data for the second group  })

Become the key of each chemical element of stackedData ???