安装完pandas后无法导入pandas。

Question

我通过pip运行以下命令来安装 pandas：

sudo pip install pandas --upgrade

它会输出

Requirement already up-to-date: pandas in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages
Requirement already up-to-date: numpy>=1.7.0 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
Requirement already up-to-date: python-dateutil>=2 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
Requirement already up-to-date: pytz>=2011k in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
Requirement already up-to-date: six>=1.5 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from python-dateutil>=2->pandas)

然而，当我使用命令行中的python3时，我无法导入pandas：

$ python3
>>> import pandas
>>> Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named 'pandas'

看起来这个位置是正确的，因为

which python3 

位于以下位置：

/opt/local/bin/python3

在Python3中执行

 >>> import sys
 >>> print(sys.version)

输出

'3.4.5 (default, Jun 27 2016, 04:57:21) \n[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)]'

为什么我无法导入pandas？

编辑：我正在使用pip3版本：

pip --version

输出

pip 8.1.2 from /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (python 3.4)

- ShanZhengYang

---

which pip 告诉你什么？ - jxramos

@jxramos /opt/local/bin/pip - ShanZhengYang

嗯，看起来和Python3是同一个位置。我曾经在安装了多个Python版本并且pip安装到了我不想要的版本时遇到过这种问题。你有安装Python2吗？检查它的已安装模块，或者尝试添加一些全新的模块并查看它们被安装到哪里。 - jxramos

@JohnGordon '/Users/shanzhengyang/src/bayesrl', '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages/tables-3.2.4.dev0-py3.4-macosx-10.11-x86_64.egg', '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python34.zip', '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4' - ShanZhengYang

@JohnGordon '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/plat-darwin', '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/lib-dynload', '/Users/shanzhengyang/Library/Python/3.4/lib/python/site-packages', '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages'] - ShanZhengYang

Answer 1

看起来您的操作系统默认使用pip2。可以通过键入以下内容进行检查：

$ pip --version
pip 8.1.2 from /usr/local/lib/python2.7/dist-packages (python 2.7)

尝试使用以下命令来使用pip3：

sudo pip3 install pandas --upgrade

- frist

---

对于 pip --version，我得到了 pip 8.1.2 from /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (python 3.4)。但恐怕这不是问题所在。 - ShanZhengYang

@ShanZhengYang 尝试执行 sys.path.insert(0, '/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages') 然后 import pandas。或者像这样使用 PYTHONPATH 启动 python3：PYTHONPATH=/opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages:$PYTHONPATH python3。 - frist