ModuleNotFoundError：即使安装了包，也没有名为“matplotlib”的模块

Question

我正在 MacOS Mojave 10.14.2 上使用 python 3.7 构建 GIS 应用程序。 我已经使用 miniconda 设置了一个名为“MG”的环境，并安装了以下软件包

# packages in environment at /Users/mousetsof/miniconda3/envs/MG:
Name                    Version                   Build  Channel
anaconda                  custom                   py37_0  
attrs                     18.2.0                     py_0    conda-forge
blas                      1.0                         mkl  
boost-cpp                 1.68.0               h3a22d5f_0    conda-forge
bzip2                     1.0.6                         1    conda-forge
ca-certificates           2018.11.29           ha4d7672_0    conda-forge
cairo                     1.14.12              h276e583_5    conda-forge
certifi                   2018.11.29            py37_1000    conda-forge
click                     7.0                        py_0    conda-forge
click-plugins             1.0.4                      py_0    conda-forge
cligj                     0.5.0                      py_0    conda-forge
curl                      7.63.0               h74213dd_0    conda-forge
cycler                    0.10.0                     py_1    conda-forge
expat                     2.2.6                h0a44026_0    anaconda
fiona                     1.8.4            py37hfc77a4a_1    conda-forge
fontconfig                2.13.1               hce039c3_0    conda-forge
freetype                  2.9.1                h6debe1e_4    conda-forge
freexl                    1.0.5                h470a237_2    conda-forge
gdal                      2.3.2            py37hfc77a4a_2    conda-forge
geos                      3.7.0                hfc679d8_0    conda-forge
geotiff                   1.4.3                h9c44c65_0    conda-forge
gettext                   0.19.8.1             h1f1d5ed_1    conda-forge
giflib                    5.1.4                h470a237_1    conda-forge
glib                      2.56.2               h464dc38_1    conda-forge
hdf4                      4.2.13               h951d187_2    conda-forge
hdf5                      1.10.4          nompi_h5598ddc_1105    conda-forge
icu                       58.2                 hfc679d8_0    conda-forge
intel-openmp              2019.1                      144  
jpeg                      9c                   h470a237_1    conda-forge
json-c                    0.13.1               h470a237_1    conda-forge
kealib                    1.4.10               heffcb4b_2    conda-forge
kiwisolver                1.0.1            py37h2d50403_2    conda-forge
krb5                      1.16.3               hbb41f41_0    conda-forge
libcurl                   7.63.0               hbdb9355_0    conda-forge
libcxx                    7.0.0                h2d50403_2    conda-forge
libdap4                   3.19.1               h18059cb_1    conda-forge
libedit                   3.1.20170329         haf1bffa_1    conda-forge
libffi                    3.2.1                hfc679d8_5    conda-forge
libgdal                   2.3.2                h9c3506f_2    conda-forge
libgfortran               3.0.1                h93005f0_2  
libiconv                  1.15                 h470a237_4    conda-forge
libkml                    1.3.0                he469717_9    conda-forge
libnetcdf                 4.6.2                h2c3f975_1    conda-forge
libpng                    1.6.36               ha92aebf_0    conda-forge
libpq                     10.6                 hf16a0db_0    conda-forge
libspatialindex           1.8.5                hfc679d8_3    conda-forge
libspatialite             4.3.0a              h201a3a7_25    conda-forge
libssh2                   1.8.0                h5b517e9_3    conda-forge
libtiff                   4.0.10               he6b73bb_1    conda-forge
libxml2                   2.9.8                h422b904_5    conda-forge
llvm-meta                 7.0.0                         0    conda-forge
matplotlib                3.0.2                    py37_1    conda-forge
matplotlib-base           3.0.2            py37hb2d221d_1    conda-forge
mkl                       2019.1                      144  
mkl_fft                   1.0.6            py37h27c97d8_0  
mkl_random                1.0.2            py37h27c97d8_0  
munch                     2.3.2                      py_0    conda-forge
ncurses                   6.1                  hfc679d8_2    conda-forge
numpy                     1.15.4           py37hacdab7b_0  
numpy-base                1.15.4           py37h6575580_0  
openjpeg                  2.3.0                h316dc23_3    conda-forge
openssl                   1.0.2p               h470a237_2    conda-forge
pandas                    0.23.4           py37h6440ff4_0    anaconda
pcre                      8.42                 h378b8a2_0    anaconda
pip                       18.1                  py37_1000    conda-forge
pixman                    0.34.0               h470a237_3    conda-forge
poppler                   0.67.0               hdf8a1b3_2    conda-forge
poppler-data              0.4.9                         1    conda-forge
postgresql                10.6                 ha408888_0    conda-forge
proj4                     5.2.0                h470a237_1    conda-forge
psycopg2                  2.7.6.1          py37hdffb7b8_0    conda-forge
pyparsing                 2.3.0                      py_0    conda-forge
pyproj                    1.9.6            py37h429999c_0    conda-forge
pysal                     1.14.4.post2          py37_1001    conda-forge
pyshp                     2.0.1                      py_0    conda-forge
python                    3.7.1                h46c1a51_0    conda-forge
python-dateutil           2.7.5                    py37_0    anaconda
pytz                      2018.7                   py37_0    anaconda
readline                  7.0                  haf1bffa_1    conda-forge
rtree                     0.8.3                 py37_1000    conda-forge
scipy                     1.1.0            py37h1410ff5_2  
setuptools                40.6.3                   py37_0    conda-forge
shapely                   1.6.4            py37hcff0d60_1    conda-forge
six                       1.12.0                py37_1000    conda-forge
sqlalchemy                1.2.15           py37h470a237_0    conda-forge
sqlite                    3.26.0               hb1c47c0_0    conda-forge
time                      1.7                  h470a237_1    conda-forge
tk                        8.6.9                ha92aebf_0    conda-forge
tornado                   5.1.1            py37h470a237_0    conda-forge
tzcode                    2018g                h470a237_1    conda-forge
wheel                     0.32.3                   py37_0    conda-forge
xerces-c                  3.2.2                h5d6a6da_0    conda-forge
xz                        5.2.4                h470a237_1    conda-forge
zlib                      1.2.11               h470a237_4    conda-forge

我正在尝试使用 matplotlib 运行一个简单的脚本

import matplotlib.pyplot as plt
plt.figure(1)                # the first figure
plt.subplot(211)             # the first subplot in the first figure
plt.plot([1, 2, 3])
plt.subplot(212)             # the second subplot in the first figure
plt.plot([4, 5, 6])


plt.figure(2)                # a second figure
plt.plot([4, 5, 6])          # creates a subplot(111) by default

plt.figure(1)                # figure 1 current; subplot(212) still current
plt.subplot(211)             # make subplot(211) in figure1 current
plt.title('Easy as 1, 2, 3') # subplot 211 title

但是我收到以下错误，即使该包显示在列表中

 import matplotlib.pyplot as plt
ModuleNotFoundError: No module named 'matplotlib'

实际上，一切都很好，直到我做了一个

conda update all

并且我还安装了 QGIS3（仅适用于 python 3.6 并且还要求安装 GDAL，如果重要的话）但是我卸载了它以防它导致问题。 现在我无法让它在新的 MG 环境中再次工作。 我收到了更多错误，这是我第三次尝试创建一个全新的环境，但我仍然对 matplotlib 有问题。

Answer 1

对于像我一样通过谷歌偶然发现这个问题的人，我只是删除并重新创建了 conda 环境：

conda env remove name_of_your_env
conda env create --name the_yml_defining_your_env

有关如何创建上述 yml 的信息，请参阅 conda 文档，目前相关部分位于此处。 根据您的用例，链接的段落以及以下内容很有趣。