如果pandas使用了xlsxwriter，为什么我想直接用的时候还要安装呢？
If pandas uses xlsxwriter why do I have to install it when I want to use it directly?
为什么我必须安装 xlsxwriter 和 pip3 如果 pandas 并且我已经安装了 pandas？
pandas 是否只使用了它的一小部分依赖项？
首先，xlswriter 是 optional dependency 到 pandas 的 pandas 文档 here. Therefore, it is not installed automatically with pandas because it is not a necessary dependency. Also, you should know that xlsxwriter module is installed separately to write worksheets in an Excel 2007+ XLSX file. If this module is not installed before, pandas could not work and arise an error as you can see in this problem 。
最后，有时我们不需要手动安装xlsxwriter。例如，xlsxwriter 已安装 automatically with Anaconda，如记录 here。
为什么我必须安装 xlsxwriter 和 pip3 如果 pandas pandas？
pandas 是否只使用了它的一小部分依赖项？
首先，xlswriter 是 optional dependency 到 pandas 的 pandas 文档 here. Therefore, it is not installed automatically with pandas because it is not a necessary dependency. Also, you should know that xlsxwriter module is installed separately to write worksheets in an Excel 2007+ XLSX file. If this module is not installed before, pandas could not work and arise an error as you can see in this problem
最后，有时我们不需要手动安装xlsxwriter。例如，xlsxwriter 已安装 automatically with Anaconda，如记录 here。