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Re: [ferret_users] nc file run



Hi Mir,

On 3/5/2020 10:52 AM, Mir Kashem wrote:
Dear Ferret User,

I am very new user in pyferret. I would run to netcdf (nc) file by pyferret. I don't know how to run? 

I would know the command of.... 

a. how to see data of nc? 
b. how to plot nc file? 
c. how to convert nc to csv?  
d. how to run nc file? 

Please advise me as soon as possible.....Thank you.

Welcome to PyFerret!

NetCDF is the preferred file type for PyFerret and it reads the coordinate information and attributes to automatically make use of them in plots and analysis.  Here is a very short demo - I will include more information below about resources for you.

Open one of the exampe datasets that is part of the pyferret installation.  Look at the variables, make a plot, and write out a subset to a netCDF file,

yes? use coads_climatology

  ! list the variables in the file and show the shape of their grids,
yes? show data

     currently SET data sets:
    1> /home/users/tmap/ferret/linux/fer_dsets/data/coads_climatology.cdf  (default)
 name     title                             I         J         K         L
 SST      SEA SURFACE TEMPERATURE          1:180     1:90      ...       1:12
 AIRT     AIR TEMPERATURE                  1:180     1:90      ...       1:12
 SPEH     SPECIFIC HUMIDITY                1:180     1:90      ...       1:12
 WSPD     WIND SPEED                       1:180     1:90      ...       1:12
 UWND     ZONAL WIND                       1:180     1:90      ...       1:12
 VWND     MERIDIONAL WIND                  1:180     1:90      ...       1:12
 SLP      SEA LEVEL PRESSURE               1:180     1:90      ...       1:12
 
  ! see the coordinate variables
yes? show grid sst

    GRID GSQ1
 name       axis              # pts   start                end                 subset
 COADSX    LONGITUDE          180mr   21E                  19E(379)            full
 COADSY    LATITUDE            90 r   89S                  89N                 full
 normal    Z
 TIME      TIME                12mr   16-JAN 06:00         16-DEC 01:20        full

yes? fill/x=100:260/y=0:50/L=1 sst
yes? save/clobber/file="my_subset.nc" /x=100:260/y=0:50/L=1 sst
 LISTing to file my_subset.nc

The command LIST/FORMAT=comma/file="filename.dat"  will write a comma-separated file.  It doesn't convert gridded data to csv.  A first step making 1-dimensional variables from the data and coordinates would be needed.


Here is more general information that we have sent out about getting started:

To get started with PyFerret, please look at the documentation on the website a including the FAQ's, and try the tutorial scripts and demos. There is a single set of documentation for PyFerret and Ferret, as the older Ferret program and the newer Python-enabled PyFerret verion use almost entirely the same commands and syntax.  PyFerret can go beyond Ferret to make use of Python capabilities, but it sounds as if you want to use the Ferret command line.  Please know that every time the documentation says Ferret, the commands will also work with pyferret.

A good place to start in the documentation is the section, "Getting Started", and the sections that follow that, particularly "Thinking like a Ferret".

Many of the tutorials are available both as web pages and scripts which you have as part of your PyFerret installation and which you can run from the PyFerret command line.

The Ferret Users List is made up of knowledgeable and experienced users.  They are busy scientists and students, and so we find that they are most willing to answer specific questions. You will want to get started with some experiments of your own before you write to the list.  Having said that, please do ask your questions. Here are a few words about getting help - part 4 of this page talks about asking a good question.

Ansley Manke


Kind regards, 
Mir 

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