python pip on Windows - command 'cl.exe' failed

Question

I'm trying to install spaCy using pip install spacy but I'm getting the following error ..

I have VS 2015 installed, and I have the following Python install ..

3.5.2 |Anaconda 2.5.0 (64-bit)| (default, Jul 5 2016, 11:41:13) [MSC v.1900 64 bit (AMD64)]

I tried the following SO solutions to no avail ..

• command cl.exe failed upon pip install django_compressor
• error: command 'cl.exe' failed: No such file or directory

As well as various others. This is not a unique problem to this specific library but more generally anytime I try to install Python libraries that need C to build on Windows.

Answer 1

You are installing a package with parts written in C/C++, so you need to have cl.exe (the Microsoft C Compiler) installed on your computer and in your PATH. PATH is an environment variable that tells Windows where to find executable files.

First, ensure the C++ build tools for Visual Studio are installed.

• If you already have Visual Studio on your computer, install Desktop development with C++ from the Visual Studio Installer, which you should have in Start Menu.
• Otherwise, you can download Build Tools for Visual Studio separately from the Visual Studio downloads page (near the bottom of the page), then choose C++ build tools from the installer.

Then, instead of the normal Command Prompt or PowerShell, use one of the special command prompts in the Visual Studio folder in Start Menu. This sets up PATH automatically, so that cl.exe can be found.

• For 32-bit Python, use x86 Native Tools Command Prompt.
• For 64-bit Python, use x64 Native Tools Command Prompt.