Question

我有一个要使用MATLAB保存到netCDF中的字符串列表。但是，我在创建文件时遇到了麻烦。

method_ID是这样的char数组：

'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'
'55-059-0019-88101-1'

我尝试执行以下操作，但是它将字符串保存为一个长字符串而不是10个字符串。

filename = ['PM25_24hr_',num2str(years(y)),'_EPA_AQS.nc'];
ncfilename = ['/data3/jg3223/PM25/netCDF/',filename]; 

method_ID = char(data_PM25{:,1});

% Create the file, overwriting if already exists (Clobber) and
% 64-bit offset (Allow easier creation of files and variables which are larger
% than two gigabytes.)
mode = bitor(netcdf.getConstant('CLOBBER'),netcdf.getConstant('64BIT_OFFSET'));
ncid = netcdf.create(ncfilename,mode);

% Define (file) global attributes
globalVarId=netcdf.getConstant('GLOBAL');
netcdf.putAtt(ncid,globalVarId,'name','PM25_24hr_AQS');

[a,b] = size(method_ID);
IDDimId = netcdf.defDim(ncid,'method_ID',a*b); % I know this size is wrong, but using `length(method_ID)` runs a size error later on

% Define variables, starting with coordinate variables,
% with appropriate names, types, and dimensions
IDVarId = netcdf.defVar(ncid,'method_ID','char',IDDimId);

% Exit the "define mode", i.e., structure creation mode
netcdf.endDef(ncid);

method ID
netcdf.putVar(ncid,IDVarId,method_ID);

% Close the netCDF file
netcdf.close(ncid);

Answer 1

如果您使用“经典字符串”，则应定义两个维度。

可以使用netCDF以两种方式存储字符串：“经典字符串”和“字符串数组”（https://www.unidata.ucar.edu/software/netcdf/netcdf-4/newdocs/netcdf-c/Strings.html）。 “经典字符串”不需要netCDF 4.0+版本，并且以下答案基于此。

**We were using** 
mongoose.connect("mongodb://localhost/mean-course").then(
  (res) => {
   console.log("Connected to Database Successfully.")
  }
).catch(() => {
  console.log("Conntection to database failed.");
});

*-----> This gives url parser error*



**Correct Syntax is**:

mongoose.connect("mongodb://localhost:27017/mean-course" , { useNewUrlParser: true }).then(
  (res) => {
   console.log("Connected to Database Successfully.")
  }
).catch(() => {
  console.log("Conntection to database failed.");
});

您将获得：

%% Solution using classic string (without NETCDF-4)

ncfilename ='./AQS.nc';
uint_method=uint8('55-059-0019-88101-1');
method_ID = char(repmat(uint_method,10,1));
[a,b] = size(method_ID);  %a=10, b=19

mode = bitor(netcdf.getConstant('CLOBBER'),netcdf.getConstant('64BIT_OFFSET'));
ncid = netcdf.create(ncfilename,mode);

globalVarId=netcdf.getConstant('GLOBAL');
netcdf.putAtt(ncid,globalVarId,'name','PM25_24hr_AQS');

%IDDimId = netcdf.defDim(ncid,'method_ID',a*b);
% IDDimId = netcdf.defDim(ncid,'method_ID',length(method_ID)); % ERROR: input elements does not match the variable size
% IDVarId = netcdf.defVar(ncid,'method_ID','char',IDDimId);

IDDim1 = netcdf.defDim(ncid,'charlen',b);
IDDim2 = netcdf.defDim(ncid,'methods',a);
IDVarId = netcdf.defVar(ncid,'method_ID','char',[IDDim1 IDDim2]);

netcdf.endDef(ncid);
netcdf.putVar(ncid,IDVarId,method_ID'); %transpose
netcdf.close(ncid);

将一组字符串保存到MATLAB中的NetCDF中

1 个答案: