[R-sig-Geo] (no subject)

[Sourav Sarkar]

Your code works perfectly Zivan! Thank you very much for all your help!

Kind regards,

শনি, ৪ জুলাই, ২০২০ তারিখে ৩:১৯ PM টায় এ Zivan Karaman <
zivan.karaman using gmail.com> লিখেছেন:

> Hi Sourav,
>
> Perhaps replacing "+proj=aeqd +lat_0=cities [i,3][[1]]
> +lon_0=cities[i,2][[1]] + x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
> +no_defs"
> by
> sprintf("+proj=aeqd +lat_0=%f
> +lon_0=%f + x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
> +no_defs",  cities [i,3][[1]], cities[i,2][[1]])
> etc.
> could solve your problem.
> HTH
> Zivan
>
>
>
>
> Le sam. 4 juil. 2020 à 10:07, Sourav Sarkar <sourav.sarkar using ahduni.edu.in>
> a écrit :
>
>> Hi All,
>> I have a sf dataframe (cities) of point locations of about a hundred
>> cities
>> in India with latitudes in the second column and longitudes in the third
>> column. I am trying to create a geodesic buffer around each of these
>> points
>> by projecting them to azimuthal equidistant projection centred at the
>> respective point and then using the st_buffer function.
>>
>> The error is occuring when I try to centre the equidistant projection to
>> my
>> preferred latitude and longitude since lat_0 and lon_0 accept only numbers
>> which I do not want to put manually. From searches over the internet, it
>> seems to me that probably something related to paste or \"" needs to be
>> applied but since I am not an expert I am unable to get the correct code.
>>
>> My code looks something like this:
>> a <-st_transform(cities[i,], "+proj=aeqd +lat_0=cities [i,3][[1]]
>> +lon_0=cities[i,2][[1]] + x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
>> +no_defs")
>> buffer_aeqd =st_transform(cities[1,], "+proj=aeqd +lat_0= cities[1,3][[1]]
>> +lon_0= cities[1,2][[1]] + x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
>> +no_defs")
>> buffer_aeqd=st_buffer(buffer_aeqd, 50000)
>> buffer_aeqd=st_transform(buffer_aeqd, 4326)
>>
>> for (i in 2:nrow(cities)){
>> a =  st_transform(cities[i,], "+proj=aeqd +lat_0=cities [i,3][[1]]
>> +lon_0=cities[i,2][[1]] + x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
>> +no_defs")
>> a=st_buffer(a, 200000)
>> a=st_transform(a, 4326)
>> buffer_aeqd=rbind(buffer_aeqd, a)
>> }
>> remove(a)
>>
>> It will be very nice if you can give me some leads. Thank You very much in
>> advance.
>>
>> Yours sincerely,
>> --
>> Sourav Sarkar,
>> Assistant Professor,
>> School of Arts and Sciences,
>> Ahmedabad University
>>
>>         [[alternative HTML version deleted]]
>>
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>>
>

-- 
Sourav Sarkar,
Assistant Professor,
School of Arts and Sciences,
Ahmedabad University

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