Re: [R] How to create gridded data
If the grid is not full you need to identify the missing cells. As an example
we can remove rows 3 and 6 from DF1:
> DF1miss <- DF1[-c(3, 6), ]
> DF2miss <- xtabs(Precip~latitude+longitude, DF1miss)
> DF2miss
longitude
latitude 110.5 111 111.5 112
45.5 3.2 5.0 0.0 2.0
46 6.1 0.0 7.8 5.5
The table command inserts 0 for empty cells, but for your data zero is a valid
value so we need to identify the missing values and replace them with NA:
> DF2mod <- xtabs(~latitude+longitude, DF1miss) < 1
> DF2mod
longitude
latitude 110.5 111 111.5 112
45.5 FALSE FALSE TRUE FALSE
46 FALSE TRUE FALSE FALSE
> DF2miss[DF2mod] <- NA
> DF2miss # Print table with blanks for missing values:
longitude
latitude 110.5 111 111.5 112
45.5 3.2 5.0 2.0
46 6.1 7.8 5.5
> print(DF2miss, na.print=NA) # Print table with for missing values:
longitude
latitude 110.5 111 111.5 112
45.5 3.2 5.0 2.0
46 6.17.8 5.5
David L Carlson
Department of Anthropology
Texas A University
College Station, TX 77843-4352
From: lily li
Sent: Monday, March 25, 2019 1:18 AM
To: David L Carlson
Cc: r-help
Subject: Re: [R] How to create gridded data
Now I have new question about this post. If the grid coordinates in DF1 are not
complete, i.e. there are missing coordinates, how to fill these with -99 in the
exported DF2? Thanks.
On Thu, Nov 15, 2018 at 10:57 PM David L Carlson <mailto:dcarl...@tamu.edu>
wrote:
It would depend on the format of the gridded data. Assuming it is a data frame
like DF2 in my earlier answer, you just reverse the steps:
> DF2
110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
> DF3 <- data.frame(as.table(as.matrix(DF2)))
Var1 Var2 Freq
1 46 110.5 6.1
2 45.5 110.5 3.2
3 46 111 4.5
4 45.5 111 5.0
5 46 111.5 7.8
6 45.5 111.5 1.8
7 46 112 5.5
8 45.5 112 2.0
But the latitude and longitude get converted to factors and we lose the column
names:
> DF3 <- data.frame(as.table(as.matrix(DF2)))
> colnames(DF3) <- c("latitude", "longitude", "Precip")
> DF3$latitude <- as.numeric(as.character(DF3$latitude))
> DF3$longitude <- as.numeric(as.character(DF3$longitude))
David L Carlson
Department of Anthropology
Texas A University
College Station, TX 77843-4352
From: lily li <mailto:chocol...@gmail.com>
Sent: Tuesday, November 13, 2018 10:50 PM
To: David L Carlson <mailto:dcarl...@tamu.edu>
Cc: Sarah Goslee <mailto:sarah.gos...@gmail.com>; R mailing list
<mailto:r-help@r-project.org>
Subject: Re: [R] How to create gridded data
Thanks, Sarah's answer helps the question. Now how to change the gridded data
back to DF1 format? I don't know how to name the format, thanks.
On Tue, Nov 13, 2018 at 10:56 PM David L Carlson
<mailto:mailto:dcarl...@tamu.edu> wrote:
Sarah's answer is probably better depending on what you want to do with the
resulting data, but here's a way to go from your original DF1 to DF2:
> DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46,
+ 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5,
+ 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)),
+ class = "data.frame", row.names = c(NA, -8L))
>
# Convert to table with xtabs()
> DF2 <- xtabs(Precip~latitude+longitude, DF1)
>
# Reverse the order of the latitudes
> DF2 <- DF2[rev(rownames(DF2)), ]
> DF2
longitude
latitude 110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
# Convert to a data frame
> DF2 <- as.data.frame.matrix(DF2)
> DF2
110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
David L Carlson
Department of Anthropology
Texas A University
College Station, TX 77843-4352
-Original Message-
From: R-help <mailto:mailto:r-help-boun...@r-project.org> On Behalf Of Sarah
Goslee
Sent: Tuesday, November 13, 2018 8:16 AM
To: lily li <mailto:mailto:chocol...@gmail.com>
Cc: r-help <mailto:mailto:r-help@r-project.org>
Subject: Re: [R] How to create gridded data
If you want an actual spatial dataset, the best place to ask is R-sig-geo
R has substantial capabilities for dealing with gridded spatial data,
including in the sp, raster, and sf packages.
Here's one approach, creating a SpatialGridDataFrame, which can be
exported in any standard raster format using the rgdal package.
DF2 <- DF1
coordinates(DF2) <- ~longitude + latitude
gridded(DF2) <- TRUE
fullgrid(DF2) <- TRUE
I recommend Roger Bivand's excellent book:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.springer.com_us_book_9781461476177=DwMFaQ=ODFT-G5SujMiGrKuoJJjVg=veMG
Re: [R] How to create gridded data
Now I have new question about this post. If the grid coordinates in DF1 are
not complete, i.e. there are missing coordinates, how to fill these with
-99 in the exported DF2? Thanks.
On Thu, Nov 15, 2018 at 10:57 PM David L Carlson wrote:
> It would depend on the format of the gridded data. Assuming it is a data
> frame like DF2 in my earlier answer, you just reverse the steps:
>
> > DF2
> 110.5 111 111.5 112
> 46 6.1 4.5 7.8 5.5
> 45.5 3.2 5.0 1.8 2.0
>
> > DF3 <- data.frame(as.table(as.matrix(DF2)))
> Var1 Var2 Freq
> 1 46 110.5 6.1
> 2 45.5 110.5 3.2
> 3 46 111 4.5
> 4 45.5 111 5.0
> 5 46 111.5 7.8
> 6 45.5 111.5 1.8
> 7 46 112 5.5
> 8 45.5 112 2.0
>
> But the latitude and longitude get converted to factors and we lose the
> column names:
>
> > DF3 <- data.frame(as.table(as.matrix(DF2)))
> > colnames(DF3) <- c("latitude", "longitude", "Precip")
> > DF3$latitude <- as.numeric(as.character(DF3$latitude))
> > DF3$longitude <- as.numeric(as.character(DF3$longitude))
>
>
> David L Carlson
> Department of Anthropology
> Texas A University
> College Station, TX 77843-4352
>
> From: lily li
> Sent: Tuesday, November 13, 2018 10:50 PM
> To: David L Carlson
> Cc: Sarah Goslee ; R mailing list <
> r-help@r-project.org>
> Subject: Re: [R] How to create gridded data
>
> Thanks, Sarah's answer helps the question. Now how to change the gridded
> data back to DF1 format? I don't know how to name the format, thanks.
>
> On Tue, Nov 13, 2018 at 10:56 PM David L Carlson <mailto:dcarl...@tamu.edu>
> wrote:
> Sarah's answer is probably better depending on what you want to do with
> the resulting data, but here's a way to go from your original DF1 to DF2:
>
> > DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46,
> + 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5,
> + 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)),
> + class = "data.frame", row.names = c(NA, -8L))
> >
> # Convert to table with xtabs()
> > DF2 <- xtabs(Precip~latitude+longitude, DF1)
> >
>
> # Reverse the order of the latitudes
> > DF2 <- DF2[rev(rownames(DF2)), ]
> > DF2
> longitude
> latitude 110.5 111 111.5 112
> 46 6.1 4.5 7.8 5.5
> 45.5 3.2 5.0 1.8 2.0
>
> # Convert to a data frame
> > DF2 <- as.data.frame.matrix(DF2)
> > DF2
> 110.5 111 111.5 112
> 46 6.1 4.5 7.8 5.5
> 45.5 3.2 5.0 1.8 2.0
>
>
> David L Carlson
> Department of Anthropology
> Texas A University
> College Station, TX 77843-4352
>
>
> -Original Message-
> From: R-help <mailto:r-help-boun...@r-project.org> On Behalf Of Sarah
> Goslee
> Sent: Tuesday, November 13, 2018 8:16 AM
> To: lily li <mailto:chocol...@gmail.com>
> Cc: r-help <mailto:r-help@r-project.org>
> Subject: Re: [R] How to create gridded data
>
> If you want an actual spatial dataset, the best place to ask is R-sig-geo
>
> R has substantial capabilities for dealing with gridded spatial data,
> including in the sp, raster, and sf packages.
>
> Here's one approach, creating a SpatialGridDataFrame, which can be
> exported in any standard raster format using the rgdal package.
>
> DF2 <- DF1
> coordinates(DF2) <- ~longitude + latitude
> gridded(DF2) <- TRUE
> fullgrid(DF2) <- TRUE
>
> I recommend Roger Bivand's excellent book:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.springer.com_us_book_9781461476177=DwMFaQ=ODFT-G5SujMiGrKuoJJjVg=veMGHMCNZShld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk=vZqNKoDe8N1TzBzeK12g2oa0cBS8VD6NDCs-hUhvt5o=B73PwZQrdKUmM1ML2Y5zjaEz7xqkHlzBDCrhluogK2U=
>
> and there are abundant web tutorials.
>
> Sarah
> On Tue, Nov 13, 2018 at 2:22 AM lily li <mailto:chocol...@gmail.com>
> wrote:
> >
> > Hi R users,
> >
> > I have a question about manipulating data. For example, I have DF1 as the
> > following, how to transform it to a gridded dataset DF2? In DF2, each
> value
> > Precip is an attribute of the corresponding grid cell. So DF2 is like a
> > spatial surface, and can be imported to ArcGIS. Thanks for your help.
> >
> > DF1
> > latitude longitude Precip
> > 45.5 110.5 3.2
> > 45.5 1115.0
> > 45.5 111.5 1.8
> > 45.5 1122.0
> > 46 110.5 6.1
> > 46 111
Re: [R] How to create gridded data
It would depend on the format of the gridded data. Assuming it is a data frame
like DF2 in my earlier answer, you just reverse the steps:
> DF2
110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
> DF3 <- data.frame(as.table(as.matrix(DF2)))
Var1 Var2 Freq
1 46 110.5 6.1
2 45.5 110.5 3.2
3 46 111 4.5
4 45.5 111 5.0
5 46 111.5 7.8
6 45.5 111.5 1.8
7 46 112 5.5
8 45.5 112 2.0
But the latitude and longitude get converted to factors and we lose the column
names:
> DF3 <- data.frame(as.table(as.matrix(DF2)))
> colnames(DF3) <- c("latitude", "longitude", "Precip")
> DF3$latitude <- as.numeric(as.character(DF3$latitude))
> DF3$longitude <- as.numeric(as.character(DF3$longitude))
David L Carlson
Department of Anthropology
Texas A University
College Station, TX 77843-4352
From: lily li
Sent: Tuesday, November 13, 2018 10:50 PM
To: David L Carlson
Cc: Sarah Goslee ; R mailing list
Subject: Re: [R] How to create gridded data
Thanks, Sarah's answer helps the question. Now how to change the gridded data
back to DF1 format? I don't know how to name the format, thanks.
On Tue, Nov 13, 2018 at 10:56 PM David L Carlson <mailto:dcarl...@tamu.edu>
wrote:
Sarah's answer is probably better depending on what you want to do with the
resulting data, but here's a way to go from your original DF1 to DF2:
> DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46,
+ 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5,
+ 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)),
+ class = "data.frame", row.names = c(NA, -8L))
>
# Convert to table with xtabs()
> DF2 <- xtabs(Precip~latitude+longitude, DF1)
>
# Reverse the order of the latitudes
> DF2 <- DF2[rev(rownames(DF2)), ]
> DF2
longitude
latitude 110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
# Convert to a data frame
> DF2 <- as.data.frame.matrix(DF2)
> DF2
110.5 111 111.5 112
46 6.1 4.5 7.8 5.5
45.5 3.2 5.0 1.8 2.0
David L Carlson
Department of Anthropology
Texas A University
College Station, TX 77843-4352
-Original Message-
From: R-help <mailto:r-help-boun...@r-project.org> On Behalf Of Sarah Goslee
Sent: Tuesday, November 13, 2018 8:16 AM
To: lily li <mailto:chocol...@gmail.com>
Cc: r-help <mailto:r-help@r-project.org>
Subject: Re: [R] How to create gridded data
If you want an actual spatial dataset, the best place to ask is R-sig-geo
R has substantial capabilities for dealing with gridded spatial data,
including in the sp, raster, and sf packages.
Here's one approach, creating a SpatialGridDataFrame, which can be
exported in any standard raster format using the rgdal package.
DF2 <- DF1
coordinates(DF2) <- ~longitude + latitude
gridded(DF2) <- TRUE
fullgrid(DF2) <- TRUE
I recommend Roger Bivand's excellent book:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.springer.com_us_book_9781461476177=DwMFaQ=ODFT-G5SujMiGrKuoJJjVg=veMGHMCNZShld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk=vZqNKoDe8N1TzBzeK12g2oa0cBS8VD6NDCs-hUhvt5o=B73PwZQrdKUmM1ML2Y5zjaEz7xqkHlzBDCrhluogK2U=
and there are abundant web tutorials.
Sarah
On Tue, Nov 13, 2018 at 2:22 AM lily li <mailto:chocol...@gmail.com> wrote:
>
> Hi R users,
>
> I have a question about manipulating data. For example, I have DF1 as the
> following, how to transform it to a gridded dataset DF2? In DF2, each value
> Precip is an attribute of the corresponding grid cell. So DF2 is like a
> spatial surface, and can be imported to ArcGIS. Thanks for your help.
>
> DF1
> latitude longitude Precip
> 45.5 110.5 3.2
> 45.5 111 5.0
> 45.5 111.5 1.8
> 45.5 112 2.0
> 46 110.5 6.1
> 46 111 4.5
> 46 111.5 7.8
> 46 112 5.5
> ...
>
>
> DF2
> 6.1 4.5 7.8 5.5
> 3.2 5.0 1.8 2.0
> ...
>
--
Sarah Goslee (she/her)
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.numberwright.com=DwMFaQ=ODFT-G5SujMiGrKuoJJjVg=veMGHMCNZShld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk=vZqNKoDe8N1TzBzeK12g2oa0cBS8VD6NDCs-hUhvt5o=qSosThG59aeSFYzVFf1e-YQGbuBKVbvgVi1z9nFm884=
__
mailto:R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Dhelp=DwMFaQ=ODFT-G5SujMiGrKuoJJjVg=veMGHMCNZShld-KX-bIj4jRE_tP9ojUvB_Lqp0ieSdk=vZqNKoDe8N1TzBzeK12g2oa0cBS8VD6NDCs-hUhvt5o=2pS9yFu5bpcRyCi1vX_OEDD2Ie8ZihvOQrkDQSNu8RM=
PLEASE do read the posting guide
https://urldefense.proofp
Re: [R] How to create gridded data
Sarah's answer is probably the best approach, but to do it using very basic R
methods that predate the very good spatial support that R now has, I would
likely do this:
## Thanks, Jim Lemon, for this step:
df1 <- read.table(text=
"latitude longitude Precip
45.5 110.5 3.2
45.5 1115.0
45.5 111.5 1.8
45.5 1122.0
46 110.5 6.1
46 1114.5
46 111.5 7.8
46 1125.5",
header=TRUE)
## first sort
df1 <- df1[order(df1$latitude, df1$longitude) , ]
## convert vector of precipitations to matrix
df2 <- matrix(df1$Precip, nrow=length(unique(df1$latitude)), byrow=TRUE)
## reorder the latitudes (rows)
df2 <- df2[ nrow(df2):1 , ]
## > df2
## [,1] [,2] [,3] [,4]
## [1,] 6.1 4.5 7.8 5.5
## [2,] 3.2 5.0 1.8 2.0
## From the original question:
## DF2
## 6.1 4.5 7.8 5.5
## 3.2 5.0 1.8 2.0
## ...
--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
Lab cell 925-724-7509
On 11/13/18, 8:50 PM, "R-help on behalf of lily li"
wrote:
Thanks, Sarah's answer helps the question. Now how to change the gridded
data back to DF1 format? I don't know how to name the format, thanks.
On Tue, Nov 13, 2018 at 10:56 PM David L Carlson wrote:
> Sarah's answer is probably better depending on what you want to do with
> the resulting data, but here's a way to go from your original DF1 to DF2:
>
> > DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46,
> + 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5,
> + 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)),
> + class = "data.frame", row.names = c(NA, -8L))
> >
> # Convert to table with xtabs()
> > DF2 <- xtabs(Precip~latitude+longitude, DF1)
> >
>
> # Reverse the order of the latitudes
> > DF2 <- DF2[rev(rownames(DF2)), ]
> > DF2
> longitude
> latitude 110.5 111 111.5 112
> 46 6.1 4.5 7.8 5.5
> 45.5 3.2 5.0 1.8 2.0
>
> # Convert to a data frame
> > DF2 <- as.data.frame.matrix(DF2)
> > DF2
> 110.5 111 111.5 112
> 46 6.1 4.5 7.8 5.5
> 45.5 3.2 5.0 1.8 2.0
>
>
> David L Carlson
> Department of Anthropology
> Texas A University
> College Station, TX 77843-4352
>
>
> -Original Message-
> From: R-help On Behalf Of Sarah Goslee
> Sent: Tuesday, November 13, 2018 8:16 AM
> To: lily li
> Cc: r-help
> Subject: Re: [R] How to create gridded data
>
> If you want an actual spatial dataset, the best place to ask is R-sig-geo
>
> R has substantial capabilities for dealing with gridded spatial data,
> including in the sp, raster, and sf packages.
>
> Here's one approach, creating a SpatialGridDataFrame, which can be
> exported in any standard raster format using the rgdal package.
>
> DF2 <- DF1
> coordinates(DF2) <- ~longitude + latitude
> gridded(DF2) <- TRUE
> fullgrid(DF2) <- TRUE
>
> I recommend Roger Bivand's excellent book:
> https://www.springer.com/us/book/9781461476177
>
> and there are abundant web tutorials.
>
> Sarah
> On Tue, Nov 13, 2018 at 2:22 AM lily li wrote:
> >
> > Hi R users,
> >
> > I have a question about manipulating data. For example, I have DF1 as
the
> > following, how to transform it to a gridded dataset DF2? In DF2, each
> value
> > Precip is an attribute of the corresponding grid cell. So DF2 is like a
> > spatial surface, and can be imported to ArcGIS. Thanks for your help.
> >
> > DF1
> > latitude longitude Precip
> > 45.5 110.5 3.2
> > 45.5 1115.0
> > 45.5 111.5 1.8
> > 45.5 1122.0
> > 46 110.5 6.1
> > 46 1114.5
> > 46 111.5 7.8
> > 46 1125.5
> > ...
> >
> >
> > DF2
> > 6.1 4.5 7.8 5.5
> > 3.2 5.0 1.8 2.0
> > ...
> >
>
>
> --
> Sarah Goslee (she/her)
> http://www.numberwright.com
>
> __
> R
Re: [R] How to create gridded data
Thanks, Sarah's answer helps the question. Now how to change the gridded data back to DF1 format? I don't know how to name the format, thanks. On Tue, Nov 13, 2018 at 10:56 PM David L Carlson wrote: > Sarah's answer is probably better depending on what you want to do with > the resulting data, but here's a way to go from your original DF1 to DF2: > > > DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46, > + 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5, > + 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)), > + class = "data.frame", row.names = c(NA, -8L)) > > > # Convert to table with xtabs() > > DF2 <- xtabs(Precip~latitude+longitude, DF1) > > > > # Reverse the order of the latitudes > > DF2 <- DF2[rev(rownames(DF2)), ] > > DF2 > longitude > latitude 110.5 111 111.5 112 > 46 6.1 4.5 7.8 5.5 > 45.5 3.2 5.0 1.8 2.0 > > # Convert to a data frame > > DF2 <- as.data.frame.matrix(DF2) > > DF2 > 110.5 111 111.5 112 > 46 6.1 4.5 7.8 5.5 > 45.5 3.2 5.0 1.8 2.0 > > > David L Carlson > Department of Anthropology > Texas A University > College Station, TX 77843-4352 > > > -----Original Message----- > From: R-help On Behalf Of Sarah Goslee > Sent: Tuesday, November 13, 2018 8:16 AM > To: lily li > Cc: r-help > Subject: Re: [R] How to create gridded data > > If you want an actual spatial dataset, the best place to ask is R-sig-geo > > R has substantial capabilities for dealing with gridded spatial data, > including in the sp, raster, and sf packages. > > Here's one approach, creating a SpatialGridDataFrame, which can be > exported in any standard raster format using the rgdal package. > > DF2 <- DF1 > coordinates(DF2) <- ~longitude + latitude > gridded(DF2) <- TRUE > fullgrid(DF2) <- TRUE > > I recommend Roger Bivand's excellent book: > https://www.springer.com/us/book/9781461476177 > > and there are abundant web tutorials. > > Sarah > On Tue, Nov 13, 2018 at 2:22 AM lily li wrote: > > > > Hi R users, > > > > I have a question about manipulating data. For example, I have DF1 as the > > following, how to transform it to a gridded dataset DF2? In DF2, each > value > > Precip is an attribute of the corresponding grid cell. So DF2 is like a > > spatial surface, and can be imported to ArcGIS. Thanks for your help. > > > > DF1 > > latitude longitude Precip > > 45.5 110.5 3.2 > > 45.5 1115.0 > > 45.5 111.5 1.8 > > 45.5 1122.0 > > 46 110.5 6.1 > > 46 1114.5 > > 46 111.5 7.8 > > 46 1125.5 > > ... > > > > > > DF2 > > 6.1 4.5 7.8 5.5 > > 3.2 5.0 1.8 2.0 > > ... > > > > > -- > Sarah Goslee (she/her) > http://www.numberwright.com > > __ > R-help@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. > [[alternative HTML version deleted]] __ R-help@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.
Re: [R] How to create gridded data
Sarah's answer is probably better depending on what you want to do with the resulting data, but here's a way to go from your original DF1 to DF2: > DF1 <- structure(list(latitude = c(45.5, 45.5, 45.5, 45.5, 46, 46, 46, + 46), longitude = c(110.5, 111, 111.5, 112, 110.5, 111, 111.5, + 112), Precip = c(3.2, 5, 1.8, 2, 6.1, 4.5, 7.8, 5.5)), + class = "data.frame", row.names = c(NA, -8L)) > # Convert to table with xtabs() > DF2 <- xtabs(Precip~latitude+longitude, DF1) > # Reverse the order of the latitudes > DF2 <- DF2[rev(rownames(DF2)), ] > DF2 longitude latitude 110.5 111 111.5 112 46 6.1 4.5 7.8 5.5 45.5 3.2 5.0 1.8 2.0 # Convert to a data frame > DF2 <- as.data.frame.matrix(DF2) > DF2 110.5 111 111.5 112 46 6.1 4.5 7.8 5.5 45.5 3.2 5.0 1.8 2.0 David L Carlson Department of Anthropology Texas A University College Station, TX 77843-4352 -Original Message- From: R-help On Behalf Of Sarah Goslee Sent: Tuesday, November 13, 2018 8:16 AM To: lily li Cc: r-help Subject: Re: [R] How to create gridded data If you want an actual spatial dataset, the best place to ask is R-sig-geo R has substantial capabilities for dealing with gridded spatial data, including in the sp, raster, and sf packages. Here's one approach, creating a SpatialGridDataFrame, which can be exported in any standard raster format using the rgdal package. DF2 <- DF1 coordinates(DF2) <- ~longitude + latitude gridded(DF2) <- TRUE fullgrid(DF2) <- TRUE I recommend Roger Bivand's excellent book: https://www.springer.com/us/book/9781461476177 and there are abundant web tutorials. Sarah On Tue, Nov 13, 2018 at 2:22 AM lily li wrote: > > Hi R users, > > I have a question about manipulating data. For example, I have DF1 as the > following, how to transform it to a gridded dataset DF2? In DF2, each value > Precip is an attribute of the corresponding grid cell. So DF2 is like a > spatial surface, and can be imported to ArcGIS. Thanks for your help. > > DF1 > latitude longitude Precip > 45.5 110.5 3.2 > 45.5 1115.0 > 45.5 111.5 1.8 > 45.5 1122.0 > 46 110.5 6.1 > 46 1114.5 > 46 111.5 7.8 > 46 1125.5 > ... > > > DF2 > 6.1 4.5 7.8 5.5 > 3.2 5.0 1.8 2.0 > ... > -- Sarah Goslee (she/her) http://www.numberwright.com __ R-help@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. __ R-help@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.
Re: [R] How to create gridded data
If you want an actual spatial dataset, the best place to ask is R-sig-geo R has substantial capabilities for dealing with gridded spatial data, including in the sp, raster, and sf packages. Here's one approach, creating a SpatialGridDataFrame, which can be exported in any standard raster format using the rgdal package. DF2 <- DF1 coordinates(DF2) <- ~longitude + latitude gridded(DF2) <- TRUE fullgrid(DF2) <- TRUE I recommend Roger Bivand's excellent book: https://www.springer.com/us/book/9781461476177 and there are abundant web tutorials. Sarah On Tue, Nov 13, 2018 at 2:22 AM lily li wrote: > > Hi R users, > > I have a question about manipulating data. For example, I have DF1 as the > following, how to transform it to a gridded dataset DF2? In DF2, each value > Precip is an attribute of the corresponding grid cell. So DF2 is like a > spatial surface, and can be imported to ArcGIS. Thanks for your help. > > DF1 > latitude longitude Precip > 45.5 110.5 3.2 > 45.5 1115.0 > 45.5 111.5 1.8 > 45.5 1122.0 > 46 110.5 6.1 > 46 1114.5 > 46 111.5 7.8 > 46 1125.5 > ... > > > DF2 > 6.1 4.5 7.8 5.5 > 3.2 5.0 1.8 2.0 > ... > -- Sarah Goslee (she/her) http://www.numberwright.com __ R-help@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.
Re: [R] How to create gridded data
You might take a look at the reshape package, which switches from 'long' to
'wide' formats and vice versa in a fairly flexible way.
S Ellison
> -Original Message-
> From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of lily li
> Sent: 13 November 2018 07:22
> To: R mailing list
> Subject: [R] How to create gridded data
>
> Hi R users,
>
> I have a question about manipulating data. For example, I have DF1 as the
> following, how to transform it to a gridded dataset DF2? In DF2, each value
> Precip is an attribute of the corresponding grid cell. So DF2 is like a
> spatial surface, and can be imported to ArcGIS. Thanks for your help.
>
> DF1
> latitude longitude Precip
> 45.5 110.5 3.2
> 45.5 1115.0
> 45.5 111.5 1.8
> 45.5 1122.0
> 46 110.5 6.1
> 46 1114.5
> 46 111.5 7.8
> 46 1125.5
> ...
>
>
> DF2
> 6.1 4.5 7.8 5.5
> 3.2 5.0 1.8 2.0
> ...
>
> [[alternative HTML version deleted]]
>
> __
> R-help@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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R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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Re: [R] How to create gridded data
Hi lily,
Something like this should work:
DF1<-read.table(text=
"latitude longitude Precip
45.5 110.5 3.2
45.5 1115.0
45.5 111.5 1.8
45.5 1122.0
46 110.5 6.1
46 1114.5
46 111.5 7.8
46 1125.5",
header=TRUE)
lats<-sort(unique(DF1$latitude),decreasing=TRUE)
lons<-sort(unique(DF1$longitude))
DF2<-matrix(NA,nrow=length(lats),ncol=length(lons))
rownames(DF2)<-lats
colnames(DF2)<-lons
nval<-dim(DF1)[1]
for(val in 1:nval) {
row<-which(lats == DF1$latitude[val])
col<-which(lons == DF1$longitude[val])
DF2[row,col]<-DF1$Precip[val]
}
Jim
On Tue, Nov 13, 2018 at 6:22 PM lily li wrote:
>
> Hi R users,
>
> I have a question about manipulating data. For example, I have DF1 as the
> following, how to transform it to a gridded dataset DF2? In DF2, each value
> Precip is an attribute of the corresponding grid cell. So DF2 is like a
> spatial surface, and can be imported to ArcGIS. Thanks for your help.
>
> DF1
> latitude longitude Precip
> 45.5 110.5 3.2
> 45.5 1115.0
> 45.5 111.5 1.8
> 45.5 1122.0
> 46 110.5 6.1
> 46 1114.5
> 46 111.5 7.8
> 46 1125.5
> ...
>
>
> DF2
> 6.1 4.5 7.8 5.5
> 3.2 5.0 1.8 2.0
> ...
>
> [[alternative HTML version deleted]]
>
> __
> R-help@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.
__
R-help@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.
