Plotting bar graphs using Google's Chart API

The Google Chart API also has great support for bar graphs. In this recipe, we will produce a bar graph of two sets of inputs in the same diagram to show the usefulness of this API.

Getting ready

Install the GoogleChart package as follows:

$ cabal install hs-gchart

Create two files called input1.txt and input2.txt with numbers inserted line by line as follows:

$ cat input1.txt 
2
5
3
7
4
1
19
18
17
14
15
16

$ cat input2.txt
4
2
6
7
8
2
18
17
16
17
15
14

How to do it…

1. Import the Google Chart API library as follows:

   import Graphics.Google.Chart

2. Gather the two input values from both the text files and parse them as two separate lists of integers, as shown in the following code snippet:

   main = do
     rawInput1 <- readFile "input1.txt"
     rawInput2 <- readFile "input2.txt"
     let nums1 = map (read :: String -> Int) (lines rawInput1)
     let nums2 = map (read :: String -> Int) (lines rawInput2)

3. Set up the bar chart too...