[R] Problem with converting grib file to excel

Thu Sep 26 06:41:59 CEST 2024

Dear all;
Many thanks for your responses. Actually it is not completely a GIS file,
it is a data file which stores meteorological data of a specific region.
But the site allows downloading with grib format and as I searched to read
this type of file in R, I found the Raster Package.
In python it is possible to do this using cdsapi and xarray library, but I
am not familiar with python.
Sincerely

On Thu, Sep 26, 2024 at 2:33 AM Roy Mendelssohn - NOAA Federal via R-help <
r-help using r-project.org> wrote:

> At least for me the dataset file did not come through.  I will look at it
> if it can be made available.  It does look like the finial step of reading
> the data into raster failed,  so then did the rest of th commands.
>
> -Roy
>
>
> > On Sep 25, 2024, at 3:24 PM, CALUM POLWART <polc1410 using gmail.com> wrote:
> >
> > Noticeable lack of silence in the group on this one.
> >
> > I've not got time to test currently. But my experience of geo location
> > files - they often had more than 2 dimensional data. In other words you
> > might have a boundary of a region as an object with long and lat for
> maybe
> > 100 data points making up the region. So 200 pieces of data. All held as
> a
> > list or something similar in a single "cell" as excel would refer to it.
> >
> > My gut feeling is that's likely to make export to excel difficult without
> > data carpentry first?
> >
> > On Tue, 24 Sep 2024, 21:26 Bert Gunter, <bgunter.4567 using gmail.com> wrote:
> >
> >> You might try posting on r-sig-geo if you don't get a satisfactory
> >> response here. I assume there's a lot of expertise there on handling
> >> raster-type data.
> >>
> >> Cheers,
> >> Bert
> >>
> >> On Mon, Sep 23, 2024 at 11:31 PM javad bayat <j.bayat194 using gmail.com>
> wrote:
> >>>
> >>> Dear R users;
> >>> I have downloaded a grib file format (Met.grib) and I want to export
> its
> >>> data to excel file. Also I want to do some mathematic on some columns.
> >> But
> >>> I got error. I would be more than happy if anyone can help me to do
> >> this. I
> >>> have provided the codes and the Met.grib file in this email.
> >>> Sincerely yours
> >>>
> >>> # Load the necessary libraries
> >>>> library(raster)      # For reading GRIB files
> >>>> library(dplyr)       # For data manipulation
> >>>> library(lubridate)   # For date manipulation
> >>>> library(openxlsx)    # For writing Excel files
> >>>
> >>> # Specify the file paths
> >>>> grib_file_path <- "C:/Users/Omrab_Lab/Downloads/Met.grib"
> >>>> excel_file_path <- "C:/Users/Omrab_Lab/Downloads/Met_updated.xlsx"
> >>>
> >>> # Open the GRIB file
> >>>> raster_data <- stack(grib_file_path)
> >>>
> >>> # Check the names of the layers to identify which ones to extract
> >>>> layer_names <- names(raster_data)
> >>>> print(layer_names)  # Prints
> >>>
> >>>
> >>>> # Extract layers based on layer names - adjust as necessary
> >>>> t2m <- raster_data[[grep("t2m", layer_names)]]
> >>>> d2m <- raster_data[[grep("d2m", layer_names)]]
> >>>> tcc <- raster_data[[grep("tcc", layer_names)]]
> >>>> valid_time <- raster_data[[grep("valid_time", layer_names)]]
> >>>> t2m
> >>> class      : RasterStack
> >>> nlayers    : 0
> >>>
> >>>> # Check if the raster layers are loaded correctly
> >>>> if (is.null(t2m) || is.null(d2m) || is.null(tcc) ||
> >> is.null(valid_time))
> >>> {
> >>> +     stop("One or more raster layers could not be loaded. Please check
> >> the
> >>> layer names.")
> >>> + }
> >>>
> >>>> # Convert raster values to vectors
> >>>> t2m_values <- values(t2m)
> >>> Error in dimnames(x) <- dn :
> >>>  length of 'dimnames' [2] not equal to array extent
> >>>> d2m_values <- values(d2m)
> >>> Error in dimnames(x) <- dn :
> >>>  length of 'dimnames' [2] not equal to array extent
> >>>> tcc_values <- values(tcc)
> >>> Error in dimnames(x) <- dn :
> >>>  length of 'dimnames' [2] not equal to array extent
> >>>> valid_time_values <- values(valid_time)
> >>> Error in dimnames(x) <- dn :
> >>>  length of 'dimnames' [2] not equal to array extent
> >>>
> >>> # Check for NA values and dimensions
> >>> if (any(is.na(t2m_values)) || any(is.na(d2m_values)) || any(is.na
> >> (tcc_values))
> >>> || any(is.na(valid_time_values))) {
> >>>  warning("One or more layers contain NA values. These will be
> removed.")
> >>> }
> >>>
> >>> # Create the data frame, ensuring no NA values are included
> >>> df <- data.frame(
> >>>  t2m = t2m_values,
> >>>  d2m = d2m_values,
> >>>  tcc = tcc_values,
> >>>  valid_time = valid_time_values,
> >>>  stringsAsFactors = FALSE
> >>> )
> >>>
> >>> # Remove rows with NA values
> >>> df <- na.omit(df)
> >>>
> >>> # Convert temperatures from Kelvin to Celsius
> >>> df$t2m <- df$t2m - 273.15
> >>> df$d2m <- df$d2m - 273.15
> >>>
> >>> # Calculate relative humidity
> >>> calculate_relative_humidity <- function(t2m, d2m) {
> >>>  es <- 6.112 * exp((17.67 * t2m) / (t2m + 243.5))
> >>>  e <- 6.112 * exp((17.67 * d2m) / (d2m + 243.5))
> >>>  rh <- (e / es) * 100
> >>>  return(rh)
> >>> }
> >>> df$RH <- calculate_relative_humidity(df$t2m, df$d2m)
> >>>
> >>> # Convert valid_time from numeric to POSIXct assuming it's in seconds
> >> since
> >>> the epoch
> >>> df$valid_time <- as.POSIXct(df$valid_time, origin = "1970-01-01")
> >>>
> >>> # Extract year, month, day, and hour from valid_time
> >>> df$Year <- year(df$valid_time)
> >>> df$Month <- month(df$valid_time)
> >>> df$Day <- day(df$valid_time)
> >>> df$Hour <- hour(df$valid_time)
> >>>
> >>> # Select only the desired columns
> >>> df_selected <- df %>% select(Year, Month, Day, Hour, tcc, t2m, RH)
> >>>
> >>> # Save the updated DataFrame to an Excel file
> >>> write.xlsx(df_selected, excel_file_path, row.names = FALSE)
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> --
> >>> Best Regards
> >>> Javad Bayat
> >>> M.Sc. Environment Engineering
> >>> Alternative Mail: bayat194 using yahoo.com
> >>>
> >>>        [[alternative HTML version deleted]]
> >>>
> >>> ______________________________________________
> >>> 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
> >> https://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >>
> >> ______________________________________________
> >> 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
> >> https://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > 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
> https://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> **********************
> "The contents of this message do not reflect any position of the U.S.
> Government or NOAA."
> **********************
> Roy Mendelssohn
> Supervisory Operations Research Analyst
> NOAA/NMFS
> Environmental Research Division
> Southwest Fisheries Science Center
> ***Note new street address***
> 110 McAllister Way
> Santa Cruz, CA 95060
> Phone: (831)-420-3666
> Fax: (831) 420-3980
> e-mail: Roy.Mendelssohn using noaa.gov www: https://www.pfeg.noaa.gov/
>
> "Old age and treachery will overcome youth and skill."
> "From those who have been given much, much will be expected"
> "the arc of the moral universe is long, but it bends toward justice" -MLK
> Jr.
>
> ______________________________________________
> 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
> https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Best Regards
Javad Bayat
M.Sc. Environment Engineering
Alternative Mail: bayat194 using yahoo.com

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