rworldmap package - Warning if the number of quantiles was reduced

Question

I am using this R code:

library(rworldmap)
Data <- read.table("D:/Bla/Maps/Test.txt", header = TRUE, sep = "\t")
sPDF <- joinCountryData2Map(Data, joinCode = "ISO3",nameJoinColumn = "ISO3CountryCode")
mapCountryData(sPDF, nameColumnToPlot = "Data")

This produces a map but I get:

You asked for 7 quantiles, only 1 could be created in quantiles classification

I googled and it pointed me to this code

Not sure whether it is relevant.

This is the data I have used:

ISO3CountryCode Data
JPN 7
AUS 6
IND 6
CHN 5
GBR 5
CHE 4
IRN 4
DEU 3
EGY 3
ESP 3
LBY 3
TUN 3
USA 3
ARG 2
AUT 2
BRA 2
EST 2
GRC 2
ITA 2
TUR 2
URY 2
CHL 1
ETH 1
FRA 1
JOR 1
KEN 1
KOR 1
LTU 1
MEX 1
NLD 1
NZL 1
PER 1
POL 1
SAU 1
SRB 1
SVK 1
SVN 1
TZA 1
ZAF 1

Answer 1

It looks like by default mapCountryData() tries to fit data to quantiles for binning. You'll need to help it along a little by tweaking the catMethod parameter.

I'm not sure what your values 1 through 7 mean. If they are categories (and you want them all explicitly displayed in the legend), try:

mapCountryData(sPDF, nameColumnToPlot = "Data", catMethod="categorical")

If you want to treat all values equally on a continuous scale, try:

mapCountryData(sPDF, nameColumnToPlot = "Data", catMethod="fixedWidth")

If neither of these does do what you want, you might try altering numCats and/or catMethod see ?mapCountryData for the possible values and their meaning.