backend_qt4agg

Community matplotlib-users
1

Users,
I am working on Windows 7 with QGIS 2.4. I am trying to get a plugin installed in QGIS called Semi-Automatic Classification Plugin to work. The plugin is demonstrated here:
http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html

The first time I tried to install the QGIS plugin, I got an error message that backend_qt4agg was not installed. I installed Python(x,y) with Python 2.x, because it seemed like the easiest way to get matplotlib and a bunch of other apps/extensions installed at the same time with minimal effort. I am not a programmer and I'm not familiar with installing things from source and then configuring settings. After the Python(x,y) install, I went to QGIS and started again and tried to install the plugin. I got the same error message. Please tell me what I need to do to get this backend installed in order to get the QGIS plugin I want.

John Polo

2

I doubt that installing Python(x,y) would help because it is a self-contained distribution of python. QGIS wouldn’t necessarally know about the libraries that it provides. Your best bet is to ask this question to the QGIS people who better understands how their software is installed in the Windows environment. How QGIS is installed is critical to understanding what libraries it can and can not access.

Of course, you could also try one of the windows binary installers of matplotlib, but I don’t know if they come with the Qt4 environment or not.

Cheers!

Ben Root

···

On Thu, Feb 12, 2015 at 10:35 AM, john polo <jpolo@…4621…> wrote:

Users,

I am working on Windows 7 with QGIS 2.4. I am trying to get a plugin

installed in QGIS called Semi-Automatic Classification Plugin to work.

The plugin is demonstrated here:

http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html

The first time I tried to install the QGIS plugin, I got an error

message that backend_qt4agg was not installed. I installed Python(x,y)

with Python 2.x, because it seemed like the easiest way to get

matplotlib and a bunch of other apps/extensions installed at the same

time with minimal effort. I am not a programmer and I’m not familiar

with installing things from source and then configuring settings. After

the Python(x,y) install, I went to QGIS and started again and tried to

install the plugin. I got the same error message. Please tell me what I

need to do to get this backend installed in order to get the QGIS plugin

I want.

John Polo

Dive into the World of Parallel Programming. The Go Parallel Website,

sponsored by Intel and developed in partnership with Slashdot Media, is your

hub for all things parallel software development, from weekly thought

leadership blogs to news, videos, case studies, tutorials and more. Take a

look and join the conversation now. http://goparallel.sourceforge.net/

Matplotlib-users mailing list

Matplotlib-users@lists.sourceforge.net

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3

John,

As Ben said, the QGIS Windows installer comes with its own Python installation, which doesn’t know anything about any other Python install. Unfortunately, this apparently makes it rather difficult to install other packages. However, QGIS Python already contains Numpy and Matplotlib and PyQt4, which is what you need here. From the Plugins dropdown menu, select Python Console. In the console that opens at the bottom of the screen, you should be able to type (don’t type the > characters):

import matplotlib.pyplot as plt

plt.plot([1,2,3])

plt.show()

On my install of QGIS, that opens a pop-up window with a plot of those data points. Does this throw an error for you too?

Ryan

···

On Thu, Feb 12, 2015 at 10:35 AM, john polo <jpolo@…878…4621…> wrote:

Users,

I am working on Windows 7 with QGIS 2.4. I am trying to get a plugin

installed in QGIS called Semi-Automatic Classification Plugin to work.

The plugin is demonstrated here:

http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html

The first time I tried to install the QGIS plugin, I got an error

message that backend_qt4agg was not installed. I installed Python(x,y)

with Python 2.x, because it seemed like the easiest way to get

matplotlib and a bunch of other apps/extensions installed at the same

time with minimal effort. I am not a programmer and I’m not familiar

with installing things from source and then configuring settings. After

the Python(x,y) install, I went to QGIS and started again and tried to

install the plugin. I got the same error message. Please tell me what I

need to do to get this backend installed in order to get the QGIS plugin

I want.

John Polo

Dive into the World of Parallel Programming. The Go Parallel Website,

sponsored by Intel and developed in partnership with Slashdot Media, is your

hub for all things parallel software development, from weekly thought

leadership blogs to news, videos, case studies, tutorials and more. Take a

look and join the conversation now. http://goparallel.sourceforge.net/

Matplotlib-users mailing list

Matplotlib-users@lists.sourceforge.net

https://lists.sourceforge.net/lists/listinfo/matplotlib-users

4

Ryan,
I used the first line of your example and this was the result:
Traceback (most recent call last):
File “”, line 1, in
File “C:/OSGEO4~1/apps/qgis/./python\qgis\utils.py”, line 454, in
_import
mod = _builtin_import(name, globals, locals, fromlist, level)
ImportError: No module named matplotlib.pyplot

I'm not sure what the first command is to confirm whether a module

is installed or not, but it looks like I may need that.
Thanks, Ben and Ryan.

John
···

On 2/12/2015 10:09 AM, Ryan Nelson
wrote:

John,

      As Ben said, the QGIS Windows installer comes with its own

Python installation, which doesn’t know anything about any
other Python install. Unfortunately, this apparently makes it
rather difficult to install other packages. However, QGIS
Python already contains Numpy and Matplotlib and PyQt4, which
is what you need here. From the Plugins dropdown menu, select
Python Console. In the console that opens at the bottom of the
screen, you should be able to type (don’t type the >
characters):

import matplotlib.pyplot as plt

plt.plot([1,2,3])

plt.show()

      On my install of QGIS, that opens a pop-up window with a

plot of those data points. Does this throw an error for you
too?

Ryan

      On Thu, Feb 12, 2015 at 10:35 AM, john

polo <jpolo@…4621…>
wrote:

Users,

        I am working on Windows 7 with QGIS 2.4. I am trying to get

a plugin

        installed in QGIS called Semi-Automatic Classification

Plugin to work.

        The plugin is demonstrated here:

        [http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html](http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html)



        The first time I tried to install the QGIS plugin, I got an

error

        message that backend_qt4agg was not installed. I installed

Python(x,y)

        with Python 2.x, because it seemed like the easiest way to

get

        matplotlib and a bunch of other apps/extensions installed at

the same

        time with minimal effort. I am not a programmer and I'm not

familiar

        with installing things from source and then configuring

settings. After

        the Python(x,y) install, I went to QGIS and started again

and tried to

        install the plugin. I got the same error message. Please

tell me what I

        need to do to get this backend installed in order to get the

QGIS plugin

        I want.



        John Polo

        Dive into the World of Parallel Programming. The Go Parallel

Website,

        sponsored by Intel and developed in partnership with

Slashdot Media, is your

        hub for all things parallel software development, from

weekly thought

        leadership blogs to news, videos, case studies, tutorials

and more. Take a

        look and join the conversation now. [http://goparallel.sourceforge.net/](http://goparallel.sourceforge.net/)

        _______________________________________________

        Matplotlib-users mailing list

        Matplotlib-users@lists.sourceforge.net

        [https://lists.sourceforge.net/lists/listinfo/matplotlib-users](https://lists.sourceforge.net/lists/listinfo/matplotlib-users)
5

John,

It’s been a little while since I installed QGIS on my machine, but I wonder if you missed a selection somewhere in the installation process. Can you reinstall QGIS? (i.e. do you have admin permissions?) There might be a number of selections you can make when installing, and my guess is that you missed a selection to have the proper Python libraries installed. Maybe there is a “Full” installation option, which puts everything on your machine. As I said on my installation of QGIS, that code works just fine, and I’m certain that I haven’t done anything special post-install.

Ryan

···

On Thu, Feb 12, 2015 at 12:37 PM, john polo <jpolo@…4621…> wrote:

Ryan,

I used the first line of your example and this was the result:

Traceback (most recent call last):

  File "<input>", line 1, in <module>

  File "C:/OSGEO4~1/apps/qgis/./python\qgis\utils.py", line 454, in

_import

    mod = _builtin_import(name, globals, locals, fromlist, level)

ImportError: No module named matplotlib.pyplot



I'm not sure what the first command is to confirm whether a module

is installed or not, but it looks like I may need that.

Thanks, Ben and Ryan.



John



  On 2/12/2015 10:09 AM, Ryan Nelson

wrote:

John,

      As Ben said, the QGIS Windows installer comes with its own

Python installation, which doesn’t know anything about any
other Python install. Unfortunately, this apparently makes it
rather difficult to install other packages. However, QGIS
Python already contains Numpy and Matplotlib and PyQt4, which
is what you need here. From the Plugins dropdown menu, select
Python Console. In the console that opens at the bottom of the
screen, you should be able to type (don’t type the >
characters):

import matplotlib.pyplot as plt

plt.plot([1,2,3])

plt.show()

      On my install of QGIS, that opens a pop-up window with a

plot of those data points. Does this throw an error for you
too?

Ryan

      On Thu, Feb 12, 2015 at 10:35 AM, john

polo <jpolo@…4621…>
wrote:

Users,

        I am working on Windows 7 with QGIS 2.4. I am trying to get

a plugin

        installed in QGIS called Semi-Automatic Classification

Plugin to work.

        The plugin is demonstrated here:

        [http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html](http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html)



        The first time I tried to install the QGIS plugin, I got an

error

        message that backend_qt4agg was not installed. I installed

Python(x,y)

        with Python 2.x, because it seemed like the easiest way to

get

        matplotlib and a bunch of other apps/extensions installed at

the same

        time with minimal effort. I am not a programmer and I'm not

familiar

        with installing things from source and then configuring

settings. After

        the Python(x,y) install, I went to QGIS and started again

and tried to

        install the plugin. I got the same error message. Please

tell me what I

        need to do to get this backend installed in order to get the

QGIS plugin

        I want.



        John Polo

        Dive into the World of Parallel Programming. The Go Parallel

Website,

        sponsored by Intel and developed in partnership with

Slashdot Media, is your

        hub for all things parallel software development, from

weekly thought

        leadership blogs to news, videos, case studies, tutorials

and more. Take a

        look and join the conversation now. [http://goparallel.sourceforge.net/](http://goparallel.sourceforge.net/)

        _______________________________________________

        Matplotlib-users mailing list

        Matplotlib-users@lists.sourceforge.net

        [https://lists.sourceforge.net/lists/listinfo/matplotlib-users](https://lists.sourceforge.net/lists/listinfo/matplotlib-users)
6

Ryan,
Thanks again. I have the permissions, I’ll reinstall.

John
···

On 2/12/2015 11:43 AM, Ryan Nelson
wrote:

John,

      It's been a little while since I installed QGIS on my

machine, but I wonder if you missed a selection somewhere in
the installation process. Can you reinstall QGIS? (i.e. do you
have admin permissions?) There might be a number of selections
you can make when installing, and my guess is that you missed
a selection to have the proper Python libraries installed.
Maybe there is a “Full” installation option, which puts
everything on your machine. As I said on my installation of
QGIS, that code works just fine, and I’m certain that I
haven’t done anything special post-install.

Ryan

      On Thu, Feb 12, 2015 at 12:37 PM, john

polo <jpolo@…4621…>
wrote:

Ryan,

          I used the first line of your example and this was the

result:

          Traceback (most recent call last):

            File "<input>", line 1, in <module>

            File "C:/OSGEO4~1/apps/qgis/./python\qgis\utils.py",

line 454, in _import

              mod = _builtin_import(name, globals, locals, fromlist,

level)

          ImportError: No module named matplotlib.pyplot



          I'm not sure what the first command is to confirm whether

a module is installed or not, but it looks like I may need
that.

          Thanks, Ben and Ryan.



              John

On 2/12/2015 10:09 AM, Ryan Nelson wrote:

John,

                    As Ben said, the QGIS Windows installer comes

with its own Python installation, which doesn’t
know anything about any other Python install.
Unfortunately, this apparently makes it rather
difficult to install other packages. However,
QGIS Python already contains Numpy and
Matplotlib and PyQt4, which is what you need
here. From the Plugins dropdown menu, select
Python Console. In the console that opens at the
bottom of the screen, you should be able to type
(don’t type the > characters):

import matplotlib.pyplot as plt

plt.plot([1,2,3])

plt.show()

                    On my install of QGIS, that opens a pop-up

window with a plot of those data points. Does
this throw an error for you too?

Ryan

                    On Thu, Feb 12, 2015 at

10:35 AM, john polo <jpolo@…4621…>
wrote:

Users,

                      I am working on Windows 7 with QGIS 2.4. I am

trying to get a plugin

                      installed in QGIS called Semi-Automatic

Classification Plugin to work.

                      The plugin is demonstrated here:

                      [http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html](http://fromgistors.blogspot.com/2013/07/working-with-multispectral-bands-in-qgis.html)



                      The first time I tried to install the QGIS

plugin, I got an error

                      message that backend_qt4agg was not installed.

I installed Python(x,y)

                      with Python 2.x, because it seemed like the

easiest way to get

                      matplotlib and a bunch of other

apps/extensions installed at the same

                      time with minimal effort. I am not a

programmer and I’m not familiar

                      with installing things from source and then

configuring settings. After

                      the Python(x,y) install, I went to QGIS and

started again and tried to

                      install the plugin. I got the same error

message. Please tell me what I

                      need to do to get this backend installed in

order to get the QGIS plugin

                      I want.



                      John Polo

                      Dive into the World of Parallel Programming.

The Go Parallel Website,

                      sponsored by Intel and developed in

partnership with Slashdot Media, is your

                      hub for all things parallel software

development, from weekly thought

                      leadership blogs to news, videos, case

studies, tutorials and more. Take a

                      look and join the conversation now. [http://goparallel.sourceforge.net/](http://goparallel.sourceforge.net/)

                      Matplotlib-users mailing list

                      Matplotlib-users@lists.sourceforge.net

                      [https://lists.sourceforge.net/lists/listinfo/matplotlib-users](https://lists.sourceforge.net/lists/listinfo/matplotlib-users)