require(rgdal)
require(sp)
x<-"rgdal"
if (!require(x,character.only=TRUE))  
{
 install.packages(pkgs=x,dependencies = TRUE)
 require(x,character.only=TRUE)
}

location

location="C:/Users/acer/documents/R/data/India Map"
india1<- readOGR(dsn = location,"IND_adm1")

Plot india

plot(india1)
slotNames(india1)
names(india1)
head(india1@data)

name are available in dataset

head(india1$NAME_1,10)

Sample plot ane state

plot(india1[india1$NAME_1=="Delhi",],col="red")
title("Delhi")

Read file that contain forest information

forestdata<-read.csv(file="C:/Users/acer/documents/R/data/RecordedForestArea.csv", stringsAsFactors = FALSE)
head(forestdata)
names(forestdata)

name are too long lets change it

colnames(forestdata)<-c("state","statearea","forestarea2005","reserved","protected","unclassed","totalforestarea","forestareapercent")
names(forestdata)
head(forestdata)

now change factpr to character

india1$NAME1 = as.character(india1$NAME1)
forestdata$state=as.character(forestdata$state)

now check all data in map and csv file are matched or not

india1$NAME_1 %in% forestdata$state

return row which is having missmatch

india1$NAME1[which(!india1$NAME1 %in% forestdata$state)]

So the issue is with and in place of & and also a name of the state Uttaranchal that was changed later to Uttrakhand

#

Let us make the relevant changes

india1$NAME1[grepl("Andaman and Nicobar",india1$NAME1)]="Andaman & Nicobar"
india1$NAME1[grepl("Dadra and Nagar Haveli",india1$NAME1)]="Dadra & Nagar Haveli"
india1$NAME1[grepl("Jammu and Kashmir",india1$NAME1)]="Jammu & Kashmir"
india1$NAME1[grepl("Daman and Diu",india1$NAME1)]="Daman & Diu"
india1$NAME1[grepl("Uttaranchal",india1$NAME1)]="Uttarakhand"

now check again the matching or nor

india1$NAME_1%in%forestdata$state