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print

Prints the value of a variable or expression.

Prototype

	procedure print (
		data       
	)

Arguments

data

A variable of any type or dimensionality, an expression, or a literal value.

Description

The print procedure displays either the variable information and value of the data parameter--when it is a variable--or simply displays the values when the parameter is an expression result or literal value.

By default, this procedure precedes every value with an index value. Scalars are preceded with "(0)". To turn this feature off, use the "-n" option on the NCL command line.

If run at the command line, print invokes a pager for scrolling through the list. The pager is either "more" or whatever the user's PAGER environment variable is set to.

If you are getting an error about the PAGER environment variable, first check that it is set to something valid:

  printenv PAGER
You can tell NCL not to use this PAGER environment variable by setting the NCL_NO_SYSTEM_PAGER environment variable:

From csh/tcsh:

  setenv NCL_NO_SYSTEM_PAGER

From bash/ksh/sh:

  export NCL_NO_SYSTEM_PAGER=

Users may use NCL's array syntax or coordinate subscripting to print specific information about a variable. Further, the argument to print can be combined with a string to print out labeled information. See examples below.

print does not allow any format control. For limited format control, use the sprintf function for floating point numbers, and sprinti for integers. To "pretty print" 2D arrays, use the write_matrix procedure.

If these options do not meet user needs, one option is to use a Fortran subroutine via a shared object to accomplish this. (See example 5 in this description of shared objects for an example of creating procedure to do special printing.)

See Also

printVarSummary, printFileVarSummary, sprinti, sprintf, write_matrix, print_table, write_table

Examples

Example 1

Print out the variable's information and all of the values:

  f = addfile ("T2m.nc", "r")
  T = f->T
  print (T)
The above yields:
   Variable: T
   Type: float
   Total Size: 72192 bytes
               18048 values
   Number of Dimensions: 3
   Dimensions and sizes:   [time | 1] x [lat | 94] x [lon | 192]
   Coordinates: 
               time: [197901..197901]
               lat: [-88.54195..88.54195]
               lon: [ 0..358.125]
   Number Of Attributes: 4
     units :       K
     short_name :  T2m
     long_name :   Temperature (2m)
     _FillValue :  1e+36
   (0,0,0) 255.49
   (0,0,1) 255.44
   (0,0,2) 255.39
   (0,0,3) 255.34
   (0,0,4) 255.3
                   [SNIP all the other values]
     
   (0,93,186)      234.23
   (0,93,187)      234.16
   (0,93,188)      234.09
   (0,93,189)      234.02
   (0,93,190)      233.95
   (0,93,191)      233.88

Example 2

print may be used with standard subscripting or coordinate subscripting to print out subsets of the data:

  print (T(0,:,61))        ; print all the latitude information
                           ; at time=0 and lon=61

  print (T(0,{-90:90},61)) ; does the same thing
                           ; note: standard and coordinate 
                           ; scripting may be combined

The two print statements each yield the same output:

     Variable: T (subsection)
     Type: float
     Total Size: 376 bytes
                 94 values
     Number of Dimensions: 1
     Dimensions and sizes:   [lat | 94]
     Coordinates: 
                 lat: [-88.54195..88.54195]
     Number Of Attributes: 6
       lon : 114.375
       time :        197901
       _FillValue :  1e+36
       long_name :   Temperature (2m)
       short_name :  T2m
       units :       K
     (0)     252.66
     (1)     254.55
     (2)     255.79
     (3)     254.4
     (4)     252.86
                     [SNIP]
     (89)    236.82
     (90)    236.79
     (91)    238.06
     (92)    237.68
     (93)    236.36

Note: NCL adds additional information when a variable subsection is printed. In this case, the "lon" and "time" attributes were added which identify the time and longitude associated with the values being printed.

Example 3

Use the max and min functions and a string to print and label the maximum and minimum values:

   print ("Minimum="+min(T) +"    Maximum="+max(T))

The above yields:

     (0)     Minimum=224.89    Maximum=308.2

Although the variable T in this example has only one time step, one could loop through time and print the max and min at each time step:

  print ("============ Min /Max Section=========")
  time = f->time
  ntim = dimsizes(time)
  do nt=0,ntim-1                                                          
    print ("time="+time(nt)+"   Minimum="+min(T(nt,:,:)) +"    Maximum="+max(T(nt,:,:)))
  end do                                                                  

The above yields:

    (0)     ============ Min /Max Section============
    (0)     time=197901   Minimum=224.89    Maximum=308.2

Example 4

To turn off the preceding index values in the output, use the "-n" option when you run NCL. For example, if you have the line:

print(ispan(0,10,1))
the output would normally look like:
 Copyright (C) 1995-2008 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 5.1.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
(0)     0
(1)     1
(2)     2
(3)     3
(4)     4
(5)     5
(6)     6
(7)     7
(8)     8
(9)     9
(10)    10
If you type:
ncl -n myscript.ncl
then you get:
 Copyright (C) 1995-2008 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 5.1.0
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
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