pip install pandas后无法导入pandas

Question

我运行下面的命令来安装pandas通过pip：

sudo pip install pandas --upgrade

哪个输出

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)

但是，当我python3在命令行中使用时，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'

看来这是在正确的位置，因为

which python3 

位于以下位置：

/opt/local/bin/python3

在python3中执行

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

产出

'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)]'

为什么我不能导入熊猫？

编辑：我正在使用 pip 版本 pip3：

pip --version

产出

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

Answer 1

看起来您的操作系统默认使用 pip2。可以通过输入以下内容来检查：

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

尝试使用pip3这样的命令：

sudo pip3 install pandas --upgrade