如何在Python中读取通用数据格式（CDF） [英] How read Common Data Format (CDF) in Python

问题描述

我需要使用python读取CDF文件。我已经找到了库，但是我不知道如何使用它。例如，在此（ Python库），我需要下载CDF库，我没有不知道在哪里下载。有CDF的下载页面，但似乎与该库无关。

I need to read CDF file with using python. I have found libraries but i did not understand how use it. For example at this(Python lib), i need to download CDF lib, i don't know where to download. There is download page for CDF but it seems irrelevant with this library.

推荐答案

答案 by @miraculixx是正确的，但是它假定您已经安装了 CDF C库。

The answer by @miraculixx is correct, but it assumes that you have already installed the CDF C Library.

如果您在SO上发现这个问题之前甚至不知道CDF文件格式是什么，这是一个易于遵循的指南。

Here's an easy to follow guide if you didn't even know what the CDF file format was before you found this question on SO.

1。下载CDF C库的最新版本：

您可以在此链接。使用 wget 抓取源代码，并将其解压缩。 注意：，以下内容将在当前文件夹中创建一个目录。/如果要以其他路径下载代码，请确保更改了

You can find the latest stable release at this link. Grab the source code using wget, and extract it. Note: the following will create a directory in the current folder ./ if you want to download the code in a different path make sure you change the code below.

wget -r -l1 -np -nd -nc http://cdaweb.gsfc.nasa.gov/pub/software/cdf/dist/latest-release/linux/ -A cdf*-dist-all.tar.gz
tar xf cdf*-dist-all.tar.gz -C ./
cd cdf*dist

2。安装所有依赖项：

SpacePy 和CDF库具有多个依赖项（如@Michal Dyzma所指出）。您可以使用 conda 或 pip 和 apt

SpacePy and the CDF Library have several dependencies (as pointed out by @Michal Dyzma). You can install them all using conda or pip, and apt.

pip install numpy scipy h5py matplotlib networkx
apt install build-essential gfortran libncurses5-dev

3。编译C库：

您应该已经下载了包含大量内容的 README.install 文件比我将提供的更多有关此步骤的详细信息。两分钱是您要检查系统和需求中哪些编译变量是必需/可选的。

You should have downloaded a README.install file that contains a lot more details on this step than I'll provide. The two cents are that you want to check which compile variables are required/optional for your system and needs.

make all.help

我将使用GNU C编译器为Linux构建发行版。我对FORTRAN界面不感兴趣，并且我的操作系统支持可共享的库。我想安装基于Curses的工具包程序，以允许使用基于命令行的交互式CDF工具（这就是为什么我们在步骤2中安装了 libncurses5-dev 依赖项的原因）。结果，这是最后的make命令：

I will be building the distribution for Linux using the GNU C compiler. I am not interested in the FORTRAN interface, and my operating system supports shareable libraries. I want to install the Curses-based toolkit programs that allow to use the command-line based interactive CDF tools (that's why we installed libncurses5-dev dependency in step 2). As a result this is the final make command:

make OS=linux ENV=gnu CURSES=yes FORTRAN=no UCOPTIONS=-O2 SHARED=yes -j4 all
make install #no sudo

安装应顺利进行且将所有文件添加到 ./ bin ， ./ include 和 ./ lib 子目录。

Installation should run smooth and add all the files in the ./bin, ./include, and ./lib sub-directories.

4。设置环境变量：

在 ./ bin 中应该有一个名为<$ c的文件$ c> definitions.B 会自动为您执行此操作，使其通过 chmod + x 可执行，并将以下行添加到您的〜/ .bashrc （注意： 1）我假设您将库安装在路径 $ HOME / Libraries / ; 2）之后。）：

There should be a file in ./bin called definitions.B that does this automatically for you, make it executable with chmod+x and add the following line to your ~/.bashrc (Note: 1) I'm assuming you installed the library at the path $HOME/Libraries/; 2) There is a space after the .):

. $HOME/Libraries/cdf/cdf36_3-dist/bin/definitions.B

重要说明：
上面的文件在第68行中有一个错误，而不是附加到环境变量 LD_LIBRARY_PATH ，它会覆盖它。修复很容易，用以下内容替换第68行：

IMPORTANT NOTE: The file above has a bug at line 68, instead of appending to environment variable LD_LIBRARY_PATH it overwrites it. The fix is easy, replace line 68 with the following:

export LD_LIBRARY_PATH=$HOME/Libraries/cdf/cdf36_3-dist/lib:$LD_LIBRARY_PATH

如果出于某些原因 B 不存在，只需添加以下内容：

If for some reason definitions.B is not there, simply add the following:

export CDF_BASE=$HOME/Libraries/cdf/cdf36_3-dist
export CDF_INC=$CDF_BASE/include
export CDF_LIB=$CDF_BASE/lib
export CDF_BIN=$CDF_BASE/bin
export LD_LIBRARY_PATH=$CDF_BASE/lib:$LD_LIBRARY_PATH

5。一切就绪，做好事：

假定您使用pip安装了 spacepy

Assuming you installed spacepy with pip the following should work out of the box:

from spacepy import pycdf
cdf = pycdf.CDF('/path/to/file.cdf')
print(cdf)

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