[R-sig-Geo] Adding colour to polylines in Leaflet

[Dhiraj Khanna]

Thank you Kent, that worked like a charm!
Regards

Dhiraj Khanna
Mob:09873263331


On Sat, Sep 1, 2018 at 7:59 PM Kent Johnson <kent3737 using gmail.com> wrote:

> You have to include the points where the colors change in both polylines.
> Here is one way:
>
> x$lastColor = dplyr::lag(x$Color)
> map <-  leaflet(x)
> map <- addTiles(map)
> for( Color in
> levels(as.factor(x$Color))){
>   map <- addPolylines(map,lng=~lon,lat=~lat,data=x[x$Color==Color |
> x$lastColor==Color,], color=~Color) }
> map
>
> Kent
>
> On Sat, Sep 1, 2018 at 8:56 AM, Dhiraj Khanna <dhirajkhanna using gmail.com>
> wrote:
>
>> @Kent they are appearing as three separate lines. I am hoping to see them
>> joint with no gaps. The transition from row 4 to row 5 is where the speed
>> has changed from 2.1 knots to 3.4 knots. I am hoping to see another line
>> from row 4 to row 5 in red colour. Similarly for the other disjoint points.
>> Regards
>>
>> Dhiraj Khanna
>> Mob:09873263331
>>
>>
>> On Sat, Sep 1, 2018 at 6:17 PM Kent Johnson <kent3737 using gmail.com> wrote:
>>
>>> Message: 5
>>>> Date: Sat, 1 Sep 2018 08:28:24 +0530
>>>> From: Dhiraj Khanna <dhirajkhanna using gmail.com>
>>>> To: r-sig-geo using r-project.org
>>>> Subject: [R-sig-Geo] Adding colour to polylines in Leaflet
>>>> Message-ID:
>>>>         <
>>>> CANHhK329-Y7hPJD9gSOs24mSqGkrjC481oQspNAgVisAw2JBoQ using mail.gmail.com>
>>>> Content-Type: text/plain; charset="utf-8"
>>>>
>>>> I am working with shipping data where I get the dynamic parameters of a
>>>> ship like its position, speed, heading and rate of turn. I am then
>>>> trying
>>>> to plot this on a leaflet map and trying to colour the polylines based
>>>> on
>>>> the speed, but it always shows up in the same colour. Here’s some sample
>>>> data:
>>>>
>>>> <snip>
>>>> This is the code I have tried which doesn’t work:-
>>>>
>>>> map <-  leaflet(x) map <- addTiles(map) for( Color in
>>>> levels(as.factor(x$Color))){   map <- addPolylines(map,
>>>> lng=~lon,lat=~lat,data=x[x$Color==Color,], color=~Color) } map
>>>>
>>>> Regards
>>>> Dhiraj Khanna
>>>> Mob:09873263331
>>>
>>>
>>> What are you expecting to see? When I run your code I get a map with
>>> three lines, one red, one orange and one yellow.
>>>
>>> Kent
>>>
>>>
>

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