 # Working with Arrays using D3.js

In general, whenever we are using D3  we are using for data visualization and if we try to understand the term data visualization in depth then it is nothing but it is a result of a lot of data manipulation using Array. So before starting working with Arrays using D3.js let’s get the understanding of Arrays briefly. ARRAYS: Arrays is used to store the collection of an element of like types, which is typically used to store fixed sized sequential collection of elements.  We can think of arrays as a collection of variables which is are of the same data types.

example:   var  data = [20,10,50,80,5]

We can easily implement or configuring API of arrays using d3.js in one easy step shown below and makes use of it for data visualization. If you are familiar with the core javascript then you must be familiar with the techniques or methods of an arrays like to find the minimum or maximum number in the array. Similarly, we have a few techniques in D3.js that we will discuss below.

Methods of Array in D3.js
1: d3.min(data):  It will return the minimum value from the array name data given above. Output: So the output we get by rendering the above script is 10 as it is the minimum number given in the array of data.

2: d3.max(data):  It will return the maximum value from the array name data given above. Output: So the output we get by rendering the above script is 80 as it is the maximum number given in the array of data.

3: d3.extent(data):  The extent method in the Array API of D3 is used to fetch both minimum and maximum value from the given array. Output: Now we get 2 output value as a result of min and max value in an array i.e In our case minimum value = 10 and maximum value = 80.

4: d3.sum(data):  This method is useful when we need to find the sum of all the numbers in a given array. It will also may results in zero(0) if the array is empty. Output: In this case, we will get the sum of all the numbers given in arrays i.e 218.

5: d3.mean(data): This method will return the mean of the given numbers in the data array. Output:
The mean of the above array data is 43.6.

5: d3.variance(data): It will give the variance of all the given numbers in an array. Output: Result of a given script above is 814.8.

Note: To know more about variance refer to this link Calculate Variance .

Conclusion: There are also some more methods available in the Arrays API of D3.js like deviation, Quantile, etc. I hope after reading this blog you will be able to make basic use of Arrays in data visualization using d3.js. #### Written by Nitin Arora

Nitin Arora is Software Consultant at Knoldus Software LLP with 6 months of experience. He has done MCA from Banarsidas Chandiwala Institute of Information technology, Delhi(GGSIPU). He has a graduation degree in BCA from Jamia Hamdard. He has a sound knowledge of various programming languages like C, C++, Java, and scala. Also has a deep interest in frontend development like Html, CSS, Angular, Javascript. He is currently working in frontend technologies like Angular, Html, CSS, Bootstrap and Typescript. He is focused, hardworking, team-oriented member and always exploring new Technologies, His hobbies is to play cricket, volleyball, and do coding.