R raster lat lon

Section 2. This chapter goes further.

r raster lat lon

As illustrated in Figure 2. This has consequences. Many geometry operations in sffor example, assume their inputs have a projected CRS, because the GEOS functions they are based on assume projected data. In some cases the CRS is unknown, as shown below using the example of London introduced in Section 2. Datasets without a specified CRS can cause problems. Only the second operation generates a warning. The consequences of a failure to work on projected data are illustrated in Figure 6.

It is better understood as a suggestion to reproject the data onto a projected CRS. This suggestion does not always need to be heeded: performing spatial and geometric operations makes little or no difference in some cases e. But for operations involving distances such as buffering, the only way to ensure a good result is to create a projected copy of the data and run the operation on that.

This is done in the code chunk below:. The result is a new object that is identical to londonbut reprojected onto a suitable CRS the British National Grid, which has an EPSG code of in this case that has units of meters.

As pointed out above, moving one degree means moving a bit more than km at the equator to be precise:meters. This is used as the new buffer distance:. The result in Figure 6. Figure 6. The gray outline represents the UK coastline. The importance of CRSs primarily whether they are projected or geographic has been demonstrated using the example of London. The subsequent sections go into more depth, exploring which CRS to use and the details of reprojecting vector and raster objects.

In real world applications, however, CRSs are usually set automatically when data is read-in. But when should data be transformed? And into which CRS? There are no clear-cut answers to these questions and CRS selection always involves trade-offs Maling However, there are some general principles provided in this section that can help you decide.

Conversely, publishing data online with the leaflet package may require a geographic CRS. Another case is when two objects with different CRSs must be compared or combined, as shown when we try to find the distance between two objects with different CRSs:. But which CRS to use? It may come as a surprise that london and london2 are just over 2 km apart!

For geographic CRSs, the answer is often WGS84not only for web mapping covered in the previous paragraph but also because GPS datasets and thousands of raster and vector datasets are provided in this CRS by default. What about when a projected CRS is required? This means that when working with local data sources, it is likely preferable to work with the CRS in which the data was provided, to ensure compatibility, even if the official CRS is not the most accurate.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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r raster lat lon

I have a data frame in which values l are specified for Cartesian coordinates x, y as in the following minimal working example. I want to create a raster using the raster package, but my reading of the documentation has not revealed a simple method for loading data in the form that I have it into the raster cells. I've come up with a couple ways to do it using for loops, but I suspect that there's a much more direct approach that I'm missing.

Further, you may specify the CRS string. Detailed discussion is available here. Learn more. How to create a raster from a data frame in r? Ask Question. Asked 7 years ago. Active 3 years, 2 months ago.

Viewed 35k times. Gregory Gregory 3, 7 7 gold badges 24 24 silver badges 40 40 bronze badges. Active Oldest Votes. The below answer is more concise and probably more computationally efficient.

Gregory pls reconsider which is the correct answer! Pankaj Pankaj 1, 1 1 gold badge 11 11 silver badges 21 21 bronze badges. Sign up or log in Sign up using Google.

Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Making the most of your one-on-one with your manager or other leadership.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I am facing some issues converting UTM to latlon in a rasterBrick object. My code is below:. The above does not convert from UTM to latlon.

It is true my use of the older raster package version was the source of the problem as suggested by RobertH. How can I get the right PS for rasnc after which I will apply projectRaster to rasnc to get latlon coordinates. If you know what it should be, you say UTM, but what is the zone? First update your version of raster you are using ncdf instead of ncdf4, so we can see it is old ; and do not leave out code if you set the coord. Learn more. Asked 4 years, 9 months ago.

Active 4 years, 8 months ago.

Rstudio: Mapping the Spatial distribution of New Coronavirus by ggmap and plotly

Viewed times. The time series is 6-hourly from Jan to dec It is true my use of the older raster package version was the source of the problem as suggested by RobertH. Please provide more information. Why do you say it "fails to convert"?

How do you know that? And what is crs rasnc? Active Oldest Votes. The question is, how did this go wrong?Section 2. This chapter goes further. As illustrated in Figure 2.

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This has consequences. Many geometry operations in sffor example, assume their inputs have a projected CRS, because the GEOS functions they are based on assume projected data. In some cases the CRS is unknown, as shown below using the example of London introduced in Section 2. Datasets without a specified CRS can cause problems. Only the second operation generates a warning. The consequences of a failure to work on projected data are illustrated in Figure 6. It is better understood as a suggestion to reproject the data onto a projected CRS.

This suggestion does not always need to be heeded: performing spatial and geometric operations makes little or no difference in some cases e. But for operations involving distances such as buffering, the only way to ensure a good result is to create a projected copy of the data and run the operation on that.

This is done in the code chunk below:. The result is a new object that is identical to londonbut reprojected onto a suitable CRS the British National Grid, which has an EPSG code of in this case that has units of meters.

As pointed out above, moving one degree means moving a bit more than km at the equator to be precise:meters. This is used as the new buffer distance:. The result in Figure 6. The gray outline represents the UK coastline. The importance of CRSs primarily whether they are projected or geographic has been demonstrated using the example of London.

The subsequent sections go into more depth, exploring which CRS to use and the details of reprojecting vector and raster objects. In real world applications, however, CRSs are usually set automatically when data is read-in. But when should data be transformed? And into which CRS? There are no clear-cut answers to these questions and CRS selection always involves trade-offs Maling However, there are some general principles provided in this section that can help you decide.

Conversely, publishing data online with the leaflet package may require a geographic CRS. Another case is when two objects with different CRSs must be compared or combined, as shown when we try to find the distance between two objects with different CRSs:. But which CRS to use? It may come as a surprise that london and london2 are just over 2 km apart! What about when a projected CRS is required?

This means that when working with local data sources, it is likely preferable to work with the CRS in which the data was provided, to ensure compatibility, even if the official CRS is not the most accurate.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Given raster object rhow can I create a new raster with the same extent and resolution, with cell values equal to the latitude or longitude of the corresponding cell in r? If your question is about create a new raster object which has the same extent and resolution of another raster object you can use command template. A simple way to do this is to 1 duplicate raster r2 extract its coordinates with coordinatesand 3 assign the longitudes or latitudes to the new raster objects' cells.

If anyone's just looking for a global raster of latitudes to download, and less interested in how it was made, I've posted one here:. Learn more. Raster of Latitudes and Longitudes Ask Question. Asked 4 years, 8 months ago. Active 2 years, 6 months ago. Viewed 4k times. Don't forget to tag the language - without your other post we'd have no idea what environment you're attempting this in. I took the liberty of clarifying your question and adding an example raster I hope you don't mind.

Active Oldest Votes. Eko Susilo Eko Susilo 2 2 silver badges 14 14 bronze badges. Robert Hijmans Robert Hijmans Neat - didn't know about this. Now if I wanted this map for the entire globe, where could I set the extent? Thomas Pingel Thomas Pingel 1 1 gold badge 1 1 silver badge 6 6 bronze badges. Sign up or log in Sign up using Google.

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It only takes a minute to sign up. Here is what i want to do : I want to extract the value for each cell with the extract function from my rasterwhere the coordinates corresponding to this value, are also in df.

Deal with Raster and Projection in R

I did it, so i'm still working on it, and for now, i didn't see any errors. But the difficulty that i have is that i want to also get the coordinates corresponding for each value in my result of the extract. I looked on this forum, and stackoverflow and othersbut i didn't find something that i could adapt for my problem, or it's more likely that i didn't see how i could adapt it.

Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Extracting value of raster with coordinates using R? Ask Question. Asked 2 years, 6 months ago. Active 8 months ago. Viewed 14k times. I'll show you a sample of my data, it will be easier to get.

r raster lat lon

My dataframe, let's call it df. Vivien Leonard Vivien Leonard 51 1 1 gold badge 1 1 silver badge 3 3 bronze badges. Active Oldest Votes. Damn it, that's really good, working perfectly! I had a little question. The problem is : i have rows with my extract, but when i transform my raster into point, i get less than rows. Do you know where it can come from? Wait, why you should convert raster into points? Raster have coordinates, x, y and a value for each cell no?

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It only takes a minute to sign up. I am an absolute beginner of geographic data, so please, forgive me if the question is not appropriate. I would like to get a list with latitude, longitude and value. I understand that rasterToPoints should do exactly what I want, however, my latitude and longitude values look strange:. Here are further info about the raster. Also look at CRS sp definitions that specify your desired projection string.

The example in the help for the "projectRaster" is quite clear in how to do this. If you coerce your raster data into a SpatialPointsDataFrame object then you would use "spTransform" and pull the coordinates from the coordinates slot and add them to the data. Here is an example of what that would look like. I should note that it is not good practice to convert rasters to a vector object class and negates the advantages of the raster package providing memory safe processing.

It is often prudent to really think about your problem and assess if you are approaching it correctly. If the OP had provided context as to why they need [x,y] coordinates for every cell, the forum community may have been able to provide computational alternatives that would keep the problem in a raster environment. It probably wasn't clear to you that that was the problem.

See this post. Converting geographic coordinate system in R. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. R: How to get latitudes and longitudes from a RasterLayer?

Ask Question. Asked 5 years, 6 months ago. Active 8 months ago.

r raster lat lon

Viewed 31k times. Active Oldest Votes. Jeffrey Evans Jeffrey Evans One way to take your caution about avoiding data conversion to heart is to unproject the original raster perhaps to a very coarse gridcreate two grids of latitude and longitude values covering the extent of the unprojection, and project those back into the extent of the original grid.

No vector classes are created: it's entirely a set of raster operations. Actually you don't need to transfer the attributes, I'll remove that.


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