<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">边晴云, you want to change the value of an existing variable in a netcdf file.</div><div dir="ltr"><br></div>(1) As Rick indicated, change the <b>addfile</b> open mode from "rw" which is invalid, to just "w". See documentation for <b>addfile</b>.<br><br>(2) Remove this line, it is not needed:</div><div><br></div><div dir="ltr"><font face="monospace"> copy_VarMeta(data,data_v)</font><br><br>(3) Change this line:</div><div dir="ltr"><br></div><div dir="ltr"><font face="monospace"> From: fin->jperio = data_v</font></div><div dir="ltr"><font face="monospace"> To: fin->jperio = (/ data_v /)<br></font><br>This is called "value-only assignment" in the NCL users manual. This change will overwrite only the actual data values, and not try to change any metadata. I think this will avoid the define error that you are getting.</div><div dir="ltr"><br><div dir="ltr"><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Oct 27, 2020 at 8:28 AM Rick Brownrigg via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu">ncl-talk@mailman.ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Hi,</div><div><br></div><div>I don't know the issue for certain. However, "rw" is not a valid open mode -- its either "r" (read) or "w" (read-write), and I am speculating that the code is looking at only the first character and proceeding from there, in which case the file would be in read mode. "enddef" refers to ending "define mode", which is an esoteric property of NetCDF files whereby one must define structural properties (vars, shapes, dims, etc.) before writing the actual data. If you read the description of "DefineMode" at the link below, it indicates the file would only be in define mode if opened for writing.</div><div><br></div><div><div><a href="http://ncl.ucar.edu/Document/Functions/Built-in/setfileoption.shtml" target="_blank">http://ncl.ucar.edu/Document/Functions/Built-in/setfileoption.shtml</a></div></div><div><br></div><div>Again, I'm just speculating, but it would be easy to test!</div><div><br></div><div>Rick</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Oct 27, 2020 at 1:39 AM 边晴云 via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu" target="_blank">ncl-talk@mailman.ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><br>
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Dear All,
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I was trying to change the value of an int variable in a netcdf file using NCL. Followed are my code:
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<span style="font-family:Arial">begin</span><br>
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<span style="font-family:Arial">fin = addfile("<a href="http://domain_cfg.nc" target="_blank">domain_cfg.nc</a>","rw")</span><br>
<span style="font-family:Arial">data=fin->jperio</span><br>
<span style="font-family:Arial">data_v = new(dimsizes(data),typeof(data),data@_FillValue)</span><br>
<span style="font-family:Arial">data_v = 0</span><br><br>
<span style="font-family:Arial">copy_VarMeta(data,data_v)</span><br>
<span style="font-family:Arial">fin->jperio = data_v</span><br>
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<span style="font-family:Arial">end</span><br>
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However, I got the following error message:
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fatal:["NclNetCDF4.c":3073]:NclNetCDF4.c: Error in nc_def_var_chunking in file (<a href="http://domain_cfg.nc" target="_blank">domain_cfg.nc</a>) for writing, at line: 3073<br>
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line 3074 of NclNetCDF4.c: NetCDF: Attempt to define var properties, like deflate, after enddef.<br>
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I have no idea how to resolve it. Any suggestions?
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Thank you!
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Followed are some information about the netcdf file.
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netcdf domain_cfg {<br>
dimensions:<br>
x = 2710 ;<br>
y = 1542 ;<br>
z = 75 ;<br>
t = UNLIMITED ; // (1 currently)<br>
variables:<br>
float nav_lon(y, x) ;<br>
nav_lon:_Storage = "chunked" ;<br>
nav_lon:_ChunkSizes = 135, 206 ;<br>
nav_lon:_Endianness = "little" ;<br>
float nav_lat(y, x) ;<br>
nav_lat:_Storage = "chunked" ;<br>
nav_lat:_ChunkSizes = 135, 206 ;<br>
nav_lat:_Endianness = "little" ;<br>
float nav_lev(z) ;<br>
nav_lev:_Storage = "chunked" ;<br>
nav_lev:_ChunkSizes = 1 ;<br>
nav_lev:_Endianness = "little" ;<br>
double time_counter(t) ;<br>
time_counter:_Storage = "chunked" ;<br>
time_counter:_ChunkSizes = 1 ;<br>
time_counter:_Endianness = "little" ;<br>
int jpiglo ;<br>
jpiglo:_Endianness = "little" ;<br>
int jpjglo ;<br>
jpjglo:_Endianness = "little" ;<br>
int jpkglo ;<br>
jpkglo:_Endianness = "little" ;<br>
int jperio ;<br>
jperio:_Endianness = "little" ;<br>
double glamt(t, y, x) ;<br>
glamt:_Storage = "chunked" ;<br>
glamt:_ChunkSizes = 1, 135, 206 ;<br>
glamt:_Endianness = "little" ;<br>
double glamu(t, y, x) ;<br>
glamu:_Storage = "chunked" ;<br>
glamu:_ChunkSizes = 1, 135, 206 ;<br>
glamu:_Endianness = "little" ;<br>
<br>
// global attributes:<br>
:file_name = "<a href="http://domain_cfg.nc" target="_blank">domain_cfg.nc</a>" ;<br>
:TimeStamp = "24/08/2020 16:38:57 +0800" ;<br>
:_NCProperties = "version=1|netcdflibversion=4.4.1|hdf5libversion=1.8.13" ;<br>
:_SuperblockVersion = 0 ;<br>
:_IsNetcdf4 = 1 ;<br>
:_Format = "netCDF-4" ;</p></blockquote></div></blockquote></div></div></div></div></div></div>