Provided by: pnetcdf-bin_1.10.0-3ubuntu1_amd64 bug

NAME

       ncmpidump - Convert netCDF files to ASCII form (CDL)

SYNOPSIS

       ncmpidump   [-ch]   [-v   var1,...]    [-b   lang]  [-f  lang]  [-l  len]  [-n  name]  [-p
              f_digits[,d_digits]] file

       ncmpidump -k file

DESCRIPTION

       ncmpidump generates an ASCII representation of a specified netCDF file on standard output.
       The  ASCII  representation is in a form called CDL (``network Common Data form Language'')
       that can be viewed, edited, or serve as  input  to  ncmpigen.   ncmpigen  is  a  companion
       program  that  can  generate  a  binary  netCDF  file from a CDL file.  Hence ncmpigen and
       ncmpidump can be used as inverses to transform the data representation between binary  and
       ASCII representations.  See ncmpigen for a description of CDL and netCDF representations.

       ncmpidump may also be used to determine what kind of netCDF file is used (which variant of
       the netCDF file format) with the -k option.

       ncmpidump defines a default format used for each type of netCDF  data,  but  this  can  be
       changed  if  a  `C_format'  attribute  is  defined  for  a netCDF variable.  In this case,
       ncmpidump will use the `C_format'  attribute  to  format  each  value.   For  example,  if
       floating-point  data  for  the  netCDF  variable `Z' is known to be accurate to only three
       significant digits, it would be appropriate to use the variable attribute

              Z:C_format = "%.3g"

       ncmpidump may also be used as a simple browser for  netCDF  data  files,  to  display  the
       dimension  names and sizes; variable names, types, and shapes; attribute names and values;
       and optionally, the values of data for all variables or selected  variables  in  a  netCDF
       file.

       ncmpidump  uses  `_' to represent data values that are equal to the `_FillValue' attribute
       for a variable, intended to represent data that has not yet been written.  If  a  variable
       has no `_FillValue' attribute, the default fill value for the variable type is used if the
       variable is not of byte type.

OPTIONS

       -c     Show the values of coordinate variables (variables that  are  also  dimensions)  as
              well  as the declarations of all dimensions, variables, and attribute values.  Data
              values of non-coordinate variables are not included in the  output.   This  is  the
              most  suitable  option  to  use for a brief look at the structure and contents of a
              netCDF file.

       -h     Show only the header information  in  the  output,  that  is  the  declarations  of
              dimensions,  variables,  and  attributes but no data values for any variables.  The
              output is identical to using the -c option except that  the  values  of  coordinate
              variables are not included.  (At most one of -c or -h options may be present.)

       -v var1,...,varn
              The output will include data values for the specified variables, in addition to the
              declarations of all dimensions, variables, and attributes.  One or  more  variables
              must  be  specified by name in the comma-delimited list following this option.  The
              list must be a single argument to the command, hence cannot contain blanks or other
              white  space characters.  The named variables must be valid netCDF variables in the
              input-file.  The default, without this option and in the absence of the  -c  or  -h
              options, is to include data values for all variables in the output.

       -b lang
              A brief annotation in the form of a CDL comment (text beginning with the characters
              ``//'') will be included in the data section of the output for each `row' of  data,
              to  help  identify data values for multidimensional variables.  If lang begins with
              `C' or `c', then C language conventions will  be  used  (zero-based  indices,  last
              dimension  varying fastest).  If lang begins with `F' or `f', then Fortran language
              conventions will be used (one-based indices, first dimension varying fastest).   In
              either  case,  the  data  will be presented in the same order; only the annotations
              will differ.   This  option  is  useful  for  browsing  through  large  volumes  of
              multidimensional data.

       -f lang
              Full  annotations  in  the  form  of trailing CDL comments (text beginning with the
              characters ``//'') for every data value (except individual characters in  character
              arrays) will be included in the data section.  If lang begins with `C' or `c', then
              C language conventions will be used (zero-based  indices,  last  dimension  varying
              fastest).   If  lang begins with `F' or `f', then Fortran language conventions will
              be used (one-based indices, first dimension varying fastest).  In either case,  the
              data  will  be presented in the same order; only the annotations will differ.  This
              option may be useful for piping data into other  filters,  since  each  data  value
              appears on a separate line, fully identified.

       -l len Changes  the  default  maximum  line  length  (80) used in formatting lists of non-
              character data values.

       -n name
              CDL requires a name for a netCDF data set, for use by ncmpigen -b in  generating  a
              default netCDF file name.  By default, ncmpidump constructs this name from the last
              component of the pathname of the input netCDF file by stripping off  any  extension
              it  has.   Use the -n option to specify a different name.  Although the output file
              name used by ncmpigen -b can be specified, it may be wise to have ncmpidump  change
              the  default  name  to  avoid inadvertantly overwriting a valuable netCDF file when
              using ncmpidump, editing the resulting CDL file, and using ncmpigen -b to  generate
              a new netCDF file from the edited CDL file.

       -p float_digits[,double_digits]
              Specifies  default  precision  (number  of significant digits) to use in displaying
              floating-point or double precision data values for attributes  and  variables.   If
              specified,  this  value  overrides  the  value  of the `C_format' attribute for any
              variable that has such an attribute.  Floating-point data will  be  displayed  with
              float_digits  significant  digits.   If  double_digits  is  also specified, double-
              precision values will be displayed with  that  many  significant  digits.   In  the
              absence  of  any  -p  specifications,  floating-point and double-precision data are
              displayed with 7 and 15 significant digits respectively.  CDL  files  can  be  made
              smaller if less precision is required.  If both floating-point and double-precision
              precisions are specified, the two values must  appear  separated  by  a  comma  (no
              blanks)  as a single argument to the command.  If you really want every last bit of
              precision from the netCDF file  represented  in  the  CDL  file  for  all  possible
              floating-point  values,  you  will  have to specify this with -p 9,17 (according to
              Theorem 15 of the paper listed under REFERENCES).

       -k     Reports the kind of netCDF file: classic, 64-bit offset, or  64-bit  data.   Before
              netCDF version 3.6, there was only one kind of netCDF file, designated as `classic'
              (also know as format variant 1 or CDF-1).  Large file  support  introduced  another
              variant  of the format, designated as `64-bit offset' (known as format variant 2 or
              CDF-2).  Large data support introduced another variant of the format, designated as
              `64-bit data' (known as format variant 5 or CDF-5).

EXAMPLES

       Look at the structure of the data in the netCDF file `foo.nc':

              ncmpidump -c foo.nc

       Produce  an  annotated  CDL version of the structure and data in the netCDF file `foo.nc',
       using C-style indexing for the annotations:

              ncmpidump -b c foo.nc > foo.cdl

       Output data for only the variables `uwind' and `vwind' from the netCDF file `foo.nc',  and
       show the floating-point data with only three significant digits of precision:

              ncmpidump -v uwind,vwind -p 3 foo.nc

       Produce  a  fully-annotated (one data value per line) listing of the data for the variable
       `omega', using Fortran conventions for indices, and changing the netCDF  dataset  name  in
       the resulting CDL file to `omega':

              ncmpidump -v omega -f fortran -n omega foo.nc > Z.cdl

REFERENCES

        What  Every Computer Scientist should Know About Floating-Point Arithmetic, D.  Goldberg,
       ACM Computing Surveys, Vol. 23, No. 1, March 1991, pp. 5-48.

SEE ALSO

       ncmpigen(1), pnetcdf(3)

DATE

       PNETCDF_RELEASE_DATE

BUGS

       Character arrays that contain a null-byte are treated like C  strings,  so  no  characters
       after the null byte appear in the output.

       Multidimensional  character  string  arrays are not handled well, since the CDL syntax for
       breaking a long character string into several shorter lines is weak.

       There should be a way to specify that the data should be displayed in `record' order, that
       is with the all the values for `record' variables together that have the same value of the
       record dimension.