R: Bar chart from JSON

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This page looks at two typical ways in which JSON data is represented.

List of lists of name-value pairs
List of dicts of name-value pairs

For each, an R program is provided to use that JSON data to create a bar chart.

The rjson package is required.

R packages can be installed from R Studio or from the command line. Here is one way to install the R package rjson from the Windows command line using the default Windows installation path for R.

"C:\Program Files\R\R-4.0.4\bin\Rscript.exe" -e "install.packages('rjson', repos='https://cran.rstudio.com/')"

The repo parameter needs to be included and the single quotes need to be used inside the double quotes.
The path you use should include the installed version of R. The one here is 4.0.4.

Here are links to the topic series of representing and processing data.

R examples:

Python examples:

JavaScript and D3 examples:

JavaScript: SVG bar chart using D3

Julia examples:

Julia: Bar chart from JSON data using StatsPlots

... more to be added ... Here is the JSON data to be read as a list of lists of name-value pairs.

[ ["a",59900], ["b",11302], ["c",14311], ["d",34483], ["e",95247], ["f",17852], ["g",13528], ["h",62509], ["i",46347], ["j",2321], ["k",4449], ["l",25939], ["m",19154], ["n",51311], ["o",54741], ["p",9918], ["q",183], ["r",37468], ["s",44630], ["t",72396], ["u",20651], ["v",7458], ["w",18376], ["x",376], ["y",14814], ["z",234] ]

Here is the R code [#1]

library(rjson)
jsonGet1 <- function(x1) {
	invisible(sapply(jsonData1, function(data1) data1[[x1]]))
	}
jsonFs1 <- "./letters1.json"
jsonData1 <- fromJSON(file=jsonFs1)
dataFrame1 <- data.frame(sapply(1:2,jsonGet1),stringsAsFactors=FALSE)
colnames(dataFrame1) <- c("Letter","Count")
dataFrame1$Count <- as.integer(dataFrame1$Count)
cat("\n")
cat("Data frame via JSON using list of lists of name-value pairs:\n")
print(dataFrame1)
imageFs2 <- "./rx.rx-14-01.png"
png(
	imageFs2,
	width=640,
	height=240
	)
labels1 = dataFrame1$Letter
barplot(
	dataFrame1$Count,
	main="Count by Letter",
	xlab="Letter",
	ylab="Count",
	names=labels1,
	cex.lab=1.5,
	cex.axis=1.2,
	cex.main=2.0,
	cex=0.9
	)
invisible(dev.off())

The as.integer function is used to convert the Count field in dataFrame1 from character (as read from the data) to integer.

Whenever loading JSON using fromJson, the name file must be used. Otherwise, the parameter will be interpreted as JSON text and not a JSON file from which to load the text.

... more to be added ...

Here is the output of the R code.

Data frame via JSON using list of lists of name-value pairs:
   Letter Count
1       a 59900
2       b 11302
3       c 14311
4       d 34483
5       e 95247
6       f 17852
7       g 13528
8       h 62509
9       i 46347
10      j  2321
11      k  4449
12      l 25939
13      m 19154
14      n 51311
15      o 54741
16      p  9918
17      q   183
18      r 37468
19      s 44630
20      t 72396
21      u 20651
22      v  7458
23      w 18376
24      x   376
25      y 14814
26      z   234

This is a simple bar chart for the present purposes. Future topics will cover how to make it look nicer.

Here is the chart produced by the R code. Count by Letter

Here is the JSON data to be read as a list of dicts (i.e., dictionaries) with name-value pairs.

[ {"name":"a", "value":59900}, {"name":"b", "value":11302}, {"name":"c", "value":14311}, {"name":"d", "value":34483}, {"name":"e", "value":95247}, {"name":"f", "value":17852}, {"name":"g", "value":13528}, {"name":"h", "value":62509}, {"name":"i", "value":46347}, {"name":"j", "value":2321}, {"name":"k", "value":4449}, {"name":"l", "value":25939}, {"name":"m", "value":19154}, {"name":"n", "value":51311}, {"name":"o", "value":54741}, {"name":"p", "value":9918}, {"name":"q", "value":183}, {"name":"r", "value":37468}, {"name":"s", "value":44630}, {"name":"t", "value":72396}, {"name":"u", "value":20651}, {"name":"v", "value":7458}, {"name":"w", "value":18376}, {"name":"x", "value":376}, {"name":"y", "value":14814}, {"name":"z", "value":234} ]

Here is the R code [#2]

library(rjson)
jsonGet1 <- function(x1) {
	invisible(sapply(jsonData1, function(data1) data1[[x1]]))
	}
jsonFs1 <- "./letters2.json"
jsonData1 <- fromJSON(file=jsonFs1)
dataFrame1 <- data.frame(sapply(1:2,jsonGet1),stringsAsFactors=FALSE)
colnames(dataFrame1) <- c("Letter","Count")
dataFrame1$Count <- as.integer(dataFrame1$Count)
cat("\n")
cat("Data frame via JSON using list of dicts of name-value pairs:\n")
print(dataFrame1)
imageFs2 <- "./rx.rx-14-01.png"
png(
	imageFs2,
	width=640,
	height=240
	)
labels1 = dataFrame1$Letter
barplot(
	dataFrame1$Count,
	main="Count by Letter",
	xlab="Letter",
	ylab="Count",
	names=labels1,
	cex.lab=1.5,
	cex.axis=1.2,
	cex.main=2.0,
	cex=0.9
	)
invisible(dev.off())

The as.integer function is used to convert the Count field in dataFrame1 from character (as read from the data) to integer.

Whenever loading JSON using fromJson, the name file must be used. Otherwise, the parameter will be interpreted as JSON text and not a JSON file from which to load the text.

... more to be added ...

Here is the output of the R code.

Data frame via JSON using list of dicts of name-value pairs:
   Letter Count
1       a 59900
2       b 11302
3       c 14311
4       d 34483
5       e 95247
6       f 17852
7       g 13528
8       h 62509
9       i 46347
10      j  2321
11      k  4449
12      l 25939
13      m 19154
14      n 51311
15      o 54741
16      p  9918
17      q   183
18      r 37468
19      s 44630
20      t 72396
21      u 20651
22      v  7458
23      w 18376
24      x   376
25      y 14814
26      z   234