# [R] Plotting Very Large lat-lon data in x-y axes graph

Ogbos Okike giftedlife2014 @ending from gm@il@com
Tue Dec 11 15:09:10 CET 2018

```Dear All,

I have looked at the plotrix package and with what I gathered, I
tinkered with the code below and obtain the attached graph:
latlim<-c(20,45)
lonlim<-c(-180,180)
latbreaks<-seq(latlim[1],latlim[2],by=5)
lonbreaks<-seq(lonlim[1],lonlim[2],by=10)

mids<-function(x) {
lenx<-length(x)
return((x[1:(lenx-1)]+x[2:lenx])/2)
}
lonmids<-mids(lonbreaks)
latmids<-mids(latbreaks)
oolt\$loncuts<-cut(oolt\$Lon,lonbreaks)
oolt\$latcuts<-cut(oolt\$Lat,latbreaks)
counts<-table(oolt\$latcuts,oolt\$loncuts)
png("test.png")
library(plotrix)
countcol<-color.scale(counts,extremes=c("blue","red"))
library(maps)
map("world",xlim=c(-180,180),ylim=c(20,45))
w = map("world")
for(lon in 1:length(lonmids)) {
for(lat in 1:length(latmids)) {
if(counts[lat,lon] > 0)
border=countcol[lat,lon],col=countcol[lat,lon])
}
}
box()
axis(1)
axis(2)
x<-seq(-180,180,30)
y<-seq(-90,90,30)
nx = 12
ny = 6
grid(nx,ny,col = "red",lty="dotted",lwd=par("lwd"),equilogs=TRUE)

I now have the horizontal color legend.

But I have two major problems still.
(1) The black line on top of the color bar is meaningless and I want it go.
(2) I want the numerical values plotted to appear on the color bar
(see the color.legend.png attached please) such that it can be used to
interpret the map.

I would be most grateful for any further assistance.

Very best wishes
Ogbos
On Tue, Dec 11, 2018 at 11:14 AM Jim Lemon <drjimlemon using gmail.com> wrote:
>
> Hi Ogbos,
> I have been off the air for a couple of days. Look at the color.legend
> function in the plotrix package.
>
> Jim
> On Tue, Dec 11, 2018 at 12:39 PM Ogbos Okike <giftedlife2014 using gmail.com> wrote:
> >
> > Dear Jim,
> > I am still having trouble with the colour code. I await your help when
> > you are less busy.
> >
> > Thank you.
> > Best
> > Ogbos
> > On Mon, Dec 10, 2018 at 6:25 AM Ogbos Okike <giftedlife2014 using gmail.com> wrote:
> > >
> > > Dear Jim,
> > >
> > > I used a bit of my data in my attempt to follow the code.
> > >
> > > I got the attached plot after some tweaks.
> > >
> > > I would like to add horizontal color bar legend that could be used to
> > > explain the number of lightning counts at different points on the
> > > latitude band as plotted.
> > >
> > > Thank you
> > > Warm regards
> > > Ogbos
> > >
> > > On Sun, Dec 9, 2018 at 9:46 PM Jim Lemon <drjimlemon using gmail.com> wrote:
> > > >
> > > > Hi Ogbos,
> > > > Here is a slight modification of a method I use to display trip
> > > > density on a map:
> > > >
> > > > oolt<-read.table(text="Lat Lon
> > > > 30.1426 104.7854
> > > > 30.5622 105.0837
> > > > 30.0966 104.6213
> > > > 29.9795 104.8430
> > > > 39.2802 147.7295
> > > > 30.2469 104.6543
> > > > 26.4428 157.7293
> > > > 29.4782 104.5590
> > > > 32.3839 105.3293
> > > > 26.4746 157.8411
> > > > 25.1014 159.6959
> > > > 25.1242 159.6558
> > > > 30.1607 104.9100
> > > > 31.4900 -71.8919
> > > > 43.3655 -74.9994
> > > > 30.0811 104.8462
> > > > 29.0912 -85.5138
> > > > 26.6204 -80.9342
> > > > 31.5462 -71.9638
> > > > 26.8619 97.3844
> > > > 30.2534 104.6134
> > > > 29.9311 -85.3434
> > > > 26.1524 159.6806
> > > > 26.5112 158.0233
> > > > 26.5441 158.0565
> > > > 27.8901 -105.8554
> > > > 30.3175 104.7135
> > > > 26.4822 157.6127
> > > > 30.1887 104.5986
> > > > 29.5058 104.5661
> > > > 26.4010 157.5749
> > > > 30.2281 104.7585
> > > > 31.4556 110.5619
> > > > 30.1700 104.5861
> > > > 26.3911 157.4776
> > > > 30.6493 104.9949
> > > > 30.2209 104.6629
> > > > 26.0488 97.3608
> > > > 30.2142 104.8023
> > > > 30.1806 104.8158
> > > > 25.2107 160.1690
> > > > 30.6708 104.9385
> > > > 30.4152 104.7002
> > > > 30.2446 104.7804
> > > > 29.5760 -85.1535
> > > > 26.4484 92.4312
> > > > 26.3914 157.4189
> > > > 26.3986 157.4421
> > > > 30.4903 -88.2271
> > > > 30.6727 104.8768
> > > > 30.2518 104.6466
> > > > 41.6979 -78.4136
> > > > 33.7575 72.1089
> > > > 26.8333 -80.9485
> > > > 25.3103 124.0978
> > > > 30.1742 104.7554
> > > > 30.6345 104.9739
> > > > 30.2075 104.7960
> > > > 30.2226 104.7517
> > > > 30.5948 105.0532",
> > > > header=TRUE)
> > > > latlim<-c(20,45)
> > > > lonlim<-c(-90,160)
> > > > latbreaks<-seq(latlim[1],latlim[2],by=5)
> > > > lonbreaks<-seq(lonlim[1],lonlim[2],by=10)
> > > >
> > > > mids<-function(x) {
> > > >  lenx<-length(x)
> > > >  return((x[1:(lenx-1)]+x[2:lenx])/2)
> > > > }
> > > > lonmids<-mids(lonbreaks)
> > > > latmids<-mids(latbreaks)
> > > > oolt\$loncuts<-cut(oolt\$Lon,lonbreaks)
> > > > oolt\$latcuts<-cut(oolt\$Lat,latbreaks)
> > > > counts<-table(oolt\$latcuts,oolt\$loncuts)
> > > > library(plotrix)
> > > > countcol<-color.scale(counts,extremes=c("blue","red"))
> > > > map("world",xlim=c(-90,160),ylim=c(20,45))
> > > > for(lon in 1:length(lonmids)) {
> > > >  for(lat in 1:length(latmids)) {
> > > >   if(counts[lat,lon] > 0)
> > > >    draw.circle(lonmids[lon],latmids[lat],radius=sqrt(counts[lat,lon]),
> > > >     border=countcol[lat,lon],col=countcol[lat,lon])
> > > >  }
> > > > }
> > > >
> > > > If you have very large counts in some places you may need to adjust
> > > > the radius of the circles.
> > > >
> > > > Jim
> > > > On Mon, Dec 10, 2018 at 2:50 AM Ogbos Okike <giftedlife2014 using gmail.com> wrote:
> > > > >
> > > > > Dear Contributors,
> > > > >
> > > > > I have a data of the form:
> > > > > Lat          Lon
> > > > > 30.1426 104.7854
> > > > > 30.5622 105.0837
> > > > > 30.0966 104.6213
> > > > > 29.9795 104.8430
> > > > > 39.2802 147.7295
> > > > > 30.2469 104.6543
> > > > > 26.4428 157.7293
> > > > > 29.4782 104.5590
> > > > > 32.3839 105.3293
> > > > > 26.4746 157.8411
> > > > > 25.1014 159.6959
> > > > > 25.1242 159.6558
> > > > > 30.1607 104.9100
> > > > > 31.4900 -71.8919
> > > > > 43.3655 -74.9994
> > > > > 30.0811 104.8462
> > > > > 29.0912 -85.5138
> > > > > 26.6204 -80.9342
> > > > > 31.5462 -71.9638
> > > > > 26.8619 97.3844
> > > > > 30.2534 104.6134
> > > > > 29.9311 -85.3434
> > > > > 26.1524 159.6806
> > > > > 26.5112 158.0233
> > > > > 26.5441 158.0565
> > > > > 27.8901 -105.8554
> > > > > 30.3175 104.7135
> > > > > 26.4822 157.6127
> > > > > 30.1887 104.5986
> > > > > 29.5058 104.5661
> > > > > 26.4010 157.5749
> > > > > 30.2281 104.7585
> > > > > 31.4556 110.5619
> > > > > 30.1700 104.5861
> > > > > 26.3911 157.4776
> > > > > 30.6493 104.9949
> > > > > 30.2209 104.6629
> > > > > 26.0488 97.3608
> > > > > 30.2142 104.8023
> > > > > 30.1806 104.8158
> > > > > 25.2107 160.1690
> > > > > 30.6708 104.9385
> > > > > 30.4152 104.7002
> > > > > 30.2446 104.7804
> > > > > 29.5760 -85.1535
> > > > > 26.4484 92.4312
> > > > > 26.3914 157.4189
> > > > > 26.3986 157.4421
> > > > > 30.4903 -88.2271
> > > > > 30.6727 104.8768
> > > > > 30.2518 104.6466
> > > > > 41.6979 -78.4136
> > > > > 33.7575 72.1089
> > > > > 26.8333 -80.9485
> > > > > 25.3103 124.0978
> > > > > 30.1742 104.7554
> > > > > 30.6345 104.9739
> > > > > 30.2075 104.7960
> > > > > 30.2226 104.7517
> > > > > 30.5948 105.0532.
> > > > > The record is for lightning flashes in the continental U.S. and
> > > > > surrounding waters within the latitudinal band between
> > > > > 258 and 458N.
> > > > >
> > > > > I want to display the result in x-y co-ordinate plot. However, the
> > > > > data is very large such that when plotted, everything just appeared
> > > > > blurred.
> > > > >
> > > > >
> > > > > Is there a way of using color codes to  indicate the regions of higher
> > > > > or lower flash densities?
> > > > >
> > > > > I can attach the plot I generated but I am not sure if the moderator
> > > > > will allow it to go with this.
> > > > >
> > > > > I will send it in a separate email if required.
> > > > >
> > > > > Thank you so much for sparing your time.
> > > > >
> > > > > Best
> > > > > Ogbos
> > > > >
> > > > > ______________________________________________
> > > > > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > > > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > > > > and provide commented, minimal, self-contained, reproducible code.

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