# Re: VarVarWrite

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Thu, 27 Aug 2009 09:46:27 -0600

Generally speaking, "yes" the warning message can be ignored.
--------------------------------------
What does this "warning:VarVarWrite:..." mean?

"VarVarWrite" is a cryptic equivalent of "Variable to Variable Write/Copy"

Say you have x(time,lat,lon) and y(foo, lat,lon) an you have a statement

x = y ; variable-to-variable copy/write

the following will appear

warning:VarVarWrite: Dimension names for dimension number (0) don't
match,
assigning name of rhs dimension
to lhs, .....

The warning tells the user that the dimension names of the variables do
not match :-)
Dimension 0 is the "time" for variable 'x' and "foo" for variable 'y'

Then it states
assigning name of rhs dimension to lhs and overwriting coordinate
variable

The 'rhs' (right hand side) is the 'y' variable and the dimension name
is 'foo'
The 'lhs' (left hand side) is the 'x' variable and the dimension name
is 'time'
Thus, the rhs dimension name will replace [over write] the lhs dimension
name.

So after x=y statement, a printVarSummary(x) would show ==> x(foo,lat,lon)

---
Next the warning states ....
use "(/../)" if this change is not desired

the 'change' being refered to is the change in dimension names. So using

x = (/ y /)

would transfer the variable values only and *not* change any preexisting
meta data.

x = random_normal(0,30, (/10,20,30/))
y = random_normal(9,20, (/10,20,30/))
x!0 = "time"
y!0 = "foo"
y!1 = "lat"
x!1 = "lat"
x!2 = "lon"
y!2 = "lon"
printVarSummary(x) ; x(time,lat,lon)
printVarSummary(y) ; y(foo,lat,lon)

X = x ; copy: create a new variable

; overwrite an *existing* variable
x = y ; will result in warning
printVarSummary(x)

X = (/ y /) ; use (/.../) to ignore meta data
printVarSummary(X)

=================
Good luck
D

Larry McDaniel wrote:
> Hi
>
> I have the error below, from what I've read from ncl-talk history I can
> ignore the warning. Is that true?
>
> Larry
>
> warning:VarVarWrite: Dimension names for dimension number (0) don't
> match, assigning name of rhs dimension to lhs and overwriting coordinate
> variable, use "(/../)" if this change is not desired
>
>

```--
======================================================
Dennis J. Shea                  tel: 303-497-1361    |
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Climate Analysis Section                             |
Climate & Global Dynamics Div.                       |
National Center for Atmospheric Research             |
Boulder, CO  80307                                   |
USA                        email: shea 'at' ucar.edu |
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Received on Thu Aug 27 2009 - 09:46:27 MDT

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