R: Bar chart from XML

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

Nodes with attribute values
Nodes with text values

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

The XML 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 XML 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('XML', 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 XML data to be read as nodes with attributes as name-value pairs.

Here is the R code [#1]

library(XML)
xmlFs1 <- "./letters1.xml"
cat(sprintf("Data from \"%s\" (XML nodes with attributes)\n",xmlFs1))
xmlData1 <- xmlParse(file=xmlFs1,useInternalNode=TRUE)
xmlNames1 <- getNodeSet(xmlData1,"//record")
xmlNames2 <- sapply(xmlNames1,xmlGetAttr,"name")
cat("\n")
cat("NAMES via XML nodes with attributes:\n")
print(xmlNames2)
xmlValues1 <- getNodeSet(xmlData1,"//record")
xmlValues2 <- sapply(xmlValues1,xmlGetAttr,"value")
xmlValues2 <- as.integer(xmlValues2)
cat("\n")
cat("VALUES via XML nodes with attributes:\n")
print(xmlValues2)
dataFrame1 <- data.frame(xmlNames2,xmlValues2,stringsAsFactors=FALSE)
colnames(dataFrame1) <- c("Letter","Count")
imageFs2 <- "./rx.rx-15-01.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 xmlValues2 vector from character (as read from the data) to integer.

... more to be added ...

Here is the output of the R code.

Data from "./letters1.xml" (XML nodes with attributes)
NAMES via XML nodes with attributes:
 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
[20] "t" "u" "v" "w" "x" "y" "z"
VALUES via XML nodes with attributes:
 [1] 59900 11302 14311 34483 95247 17852 13528 62509 46347  2321  4449 25939
[13] 19154 51311 54741  9918   183 37468 44630 72396 20651  7458 18376   376
[25] 14814   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 XML data to be read as nodes with text values as name-value pairs.

Here is the R code [#2]

library(XML)
xmlFs1 <- "./letters2.xml"
cat(sprintf("Data from \"%s\" (XML nodes with text values)\n",xmlFs1))
xmlData1 <- xmlParse(file=xmlFs1,useInternalNode=TRUE)
xmlNames1 <- getNodeSet(xmlData1,"//record/name")
xmlNames2 <- sapply(xmlNames1,xmlValue)
cat("\n")
cat("NAMES via XML nodes with text values:\n")
print(xmlNames2)
xmlValues1 <- getNodeSet(xmlData1,"//record/value")
xmlValues2 <- sapply(xmlValues1,xmlValue)
xmlValues2 <- as.integer(xmlValues2)
cat("\n")
cat("VALUES via XML nodes with text values:\n")
print(xmlValues2)
dataFrame1 <- data.frame(xmlNames2,xmlValues2,stringsAsFactors=FALSE)
colnames(dataFrame1) <- c("Letter","Count")
imageFs2 <- "./rx.rx-15-01.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 xmlValues2 vector from character (as read from the data) to integer.

... more to be added ...

Here is the output of the R code.

Data from "./letters2.xml" (XML nodes with text values)
NAMES via XML nodes with text values:
 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
[20] "t" "u" "v" "w" "x" "y" "z"
VALUES via XML nodes with text values:
 [1] 59900 11302 14311 34483 95247 17852 13528 62509 46347  2321  4449 25939
[13] 19154 51311 54741  9918   183 37468 44630 72396 20651  7458 18376   376
[25] 14814   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