matplotlib-users

[Matplotlib-users] dates for x-axis

[questions a. <que...@gm...>]

Hi matplotlib list,
I am having trouble applying mdates in matplotlib.
I am not sure how to recognise that x-axis are dates like 20110101,
20110102, 20110103 etc.
Any feedback will be greatly appreciated!
below is the code I have so far:

import numpy as np
import matplotlib.pyplot as plt
from numpy import ma as MA
from mpl_toolkits.basemap import Basemap
import os
import glob
import matplotlib.dates as mdates

MainFolder=r"E:/Rainfall/rainfall-2011/test/"
OutputFolder=r"E:/test_out/"

rmax=[]
monthyear=[]

for (path, dirs, files) in os.walk(MainFolder):
    path=path+'/'
    for fname in files:
        if fname.endswith('.txt'):
            filename=path+fname
            fileName, fileExtension=os.path.splitext(fname)
            test=fileName.strip('r')
            test=str(test)
            monthyear.append(test)
            f=np.genfromtxt(filename, skip_header=6)
            dailymax=f.max()
            rmax.append(dailymax)
print rmax
print monthyear

x=monthyear
y=rmax

fig, ax=plt.subplots(1)

plt.plot(x,y)

fig.autofmt_xdate()
ax.fmt_xdata=mdates.DateFormatter('%Y%m%d')

plt.ylabel("Precipitation")
plt.title("Max daily Precipition Vic")
plt.savefig(OutputFolder+"MaxdailyPrecip.png")
plt.show()

Re: [Matplotlib-users] dates for x-axis

[Goyo <goy...@gm...>]

El día 12 de abril de 2012 03:46, questions anon
<que...@gm...> escribió:

> I am not sure how to recognise that x-axis are dates like 20110101,
> 20110102, 20110103 etc.

Use datetime objects instead of strings.

Goyo

Re: [Matplotlib-users] dates for x-axis

[questions a. <que...@gm...>]

I am not exactly sure how to use datetime objects instead of strings.
This is the code I am working with at the moment and the code works except
for the dates, they are just weird numbers along the x-axis.
Any help will be greatly appreciated.

import numpy as np
import matplotlib.pyplot as plt
from numpy import ma as MA
from mpl_toolkits.basemap import Basemap
from datetime import datetime
import os
from osgeo import gdal, gdalnumeric, ogr, osr
import glob
from datetime import date, timedelta
import matplotlib.dates as mdates
import time

rainmax=[]
yearmonthlist=[]
yearmonth_int=[]

OutputFolder=r"E:/test_out/"
GLOBTEMPLATE = r"e:/Rainfall/rainfall-{year}/r{year}{month:02}??.txt"

def accumulate_month(year, month):
    files = glob.glob(GLOBTEMPLATE.format(year=year, month=month))
    monthlyrain=[]
    monthlyrainaust=[]
    for ifile in files:
        f=np.genfromtxt(ifile,skip_header=6)
        monthlyrain.append(f)
    yearmonth=str(year)+str(month)
    d=datetime.strptime(yearmonth, '%Y%m')
    date_string=d.strftime('%Y%m')
    yearmonthint=int(date_string)
    yearmonth_int.append(yearmonthint)
    yearmonthlist.append(yearmonth)
    r_max=np.max(monthlyrain)
    rainmax.append(r_max)


###loop through months and years
stop_month = datetime(2011, 04, 01)
month = datetime(2011, 01, 01)
while month < stop_month:
    accumulate_month(month.year, month.month)
    month += timedelta(days=32)
    month = month.replace(day=01)


x=yearmonthlist
y=rainmax
x2=yearmonth_int

print x, y, x2

fig, ax=plt.subplots(1)

z=np.polyfit(x2,y,1)
p=np.poly1d(z)

plt.plot(x,y)
plt.plot(x,p(x2),'r--') #add trendline to plot
print "y=%.6fx+(%.6f)"%(z[0],z[1])

fig.autofmt_xdate()
ax.fmt_xdata=mdates.DateFormatter('%Y%m')
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y%m'))

plt.xlabel("year-month")
plt.ylabel("Precipitation (mm)")
plt.title("Max monthly Precipition")
plt.savefig(OutputFolder+"MaxMonthlyPrecip.png")
plt.show()





On Fri, Apr 13, 2012 at 2:31 AM, Goyo <goy...@gm...> wrote:

> El día 12 de abril de 2012 03:46, questions anon
> <que...@gm...> escribió:
>
> > I am not sure how to recognise that x-axis are dates like 20110101,
> > 20110102, 20110103 etc.
>
> Use datetime objects instead of strings.
>
> Goyo
>

Re: [Matplotlib-users] dates for x-axis

[Goyo <goy...@gm...>]

El día 18 de abril de 2012 07:59, questions anon
<que...@gm...> escribió:
> I am not exactly sure how to use datetime objects instead of strings.
> This is the code I am working with at the moment and the code works except
> for the dates, they are just weird numbers along the x-axis.

Seems like you're plotting yearmonthlist in the x axis, which is a
list of strings and each string is the concatenation of the string
representations of two numbers. So numbers in the x axis are to be
expected.

You can create datetime objects this way:

d = datetime.datetime(year, month, 1)

Then create an array of datetime objects and use it as the x parameter to plot.

Goyo

Re: [Matplotlib-users] dates for x-axis

[questions a. <que...@gm...>]

Thank you, I was able to get it to work but only if I imported datetime
within the loop, otherwise I ended up with the
AttributeError: type object 'datetime.datetime' has no attribute 'datetime'
and if I added 'import datetime' at the top of my script it had an error
where I loop through combining each month
"    stop_month = datetime(2011, 03, 01)
TypeError: 'module' object is not callable"
It seems very messy with importing datetime everywhere but I am not sure
what the problem is. Below is the code I am using that works:


import numpy as np
import matplotlib.pyplot as plt
from numpy import ma as MA
from mpl_toolkits.basemap import Basemap
from datetime import datetime
import os
from StringIO import StringIO
from osgeo import gdal, gdalnumeric, ogr, osr
import glob
from datetime import date, timedelta
import matplotlib.dates as mdates
import time

rainmax=[]
rainmin=[]
rainmean=[]
yearmonthlist=[]
yearmonth_int=[]

OutputFolder=r"E:/test_out/"
GLOBTEMPLATE = r"e:/Rainfall/rainfall-{year}/r{year}{month:02}??.txt"

def accumulate_month(year, month):
    files = glob.glob(GLOBTEMPLATE.format(year=year, month=month))
    monthlyrain=[]
    for ifile in files:
        f=np.genfromtxt(ifile,skip_header=6)
        monthlyrain.append(f)

    import datetime
    yearmonth=datetime.datetime(year,month,1)
    yearmonthlist.append(yearmonth)
    yearmonthint=str(year)+str(month)
    from datetime import date, datetime
    d=datetime.strptime(yearmonthint, '%Y%m')
    date_string=d.strftime('%Y%m')
    yearmonthint=int(date_string)
    yearmonth_int.append(yearmonthint)
    r_max, r_mean, r_min=MA.max(monthlyrain), MA.mean(monthlyrain),
MA.min(monthlyrain)
    rainmax.append(r_max)
    rainmean.append(r_mean)
    rainmin.append(r_min)


###loop through months and years
stop_month = datetime(2011, 12, 31)
month = datetime(2011, 01, 01)
while month < stop_month:
    accumulate_month(month.year, month.month)
    month += timedelta(days=32)
    month = month.replace(day=01)


### Plot timeseries of max data
x=yearmonthlist
y=rainmax
x2=yearmonth_int

print x, y, x2

fig, ax=plt.subplots(1)

z=np.polyfit(x2,y,1)
p=np.poly1d(z)

plt.plot(x,y)
plt.plot(x,p(x2),'r--') #add trendline to plot
print "y=%.6fx+(%.6f)"%(z[0],z[1])

fig.autofmt_xdate()
ax.fmt_xdata=mdates.DateFormatter('%Y%m')
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y%m'))

plt.xlabel("year-month")
plt.ylabel("Precipitation (mm)")
plt.title("Max monthly precipition")
plt.savefig(OutputFolder+"MaxMonthlyPrecip.png")
plt.show()




On Thu, Apr 19, 2012 at 2:52 AM, Goyo <goy...@gm...> wrote:

> El día 18 de abril de 2012 07:59, questions anon
> <que...@gm...> escribió:
> > I am not exactly sure how to use datetime objects instead of strings.
> > This is the code I am working with at the moment and the code works
> except
> > for the dates, they are just weird numbers along the x-axis.
>
> Seems like you're plotting yearmonthlist in the x axis, which is a
> list of strings and each string is the concatenation of the string
> representations of two numbers. So numbers in the x axis are to be
> expected.
>
> You can create datetime objects this way:
>
> d = datetime.datetime(year, month, 1)
>
> Then create an array of datetime objects and use it as the x parameter to
> plot.
>
> Goyo
>

Re: [Matplotlib-users] dates for x-axis

[Goyo <goy...@gm...>]

El día 19 de abril de 2012 05:31, questions anon
<que...@gm...> escribió:
> Thank you, I was able to get it to work but only if I imported datetime
> within the loop, otherwise I ended up with the
> AttributeError: type object 'datetime.datetime' has no attribute 'datetime'
> and if I added 'import datetime' at the top of my script it had an error
> where I loop through combining each month
> "    stop_month = datetime(2011, 03, 01)
> TypeError: 'module' object is not callable"

If you can write a standalone, minimal executable script which
reproduces the problem I'll take a look. Send it as an attachement and
add sample data files if necessary.

Goyo

Re: [Matplotlib-users] dates for x-axis

[Benjamin R. <ben...@ou...>]

On Thu, Apr 19, 2012 at 1:21 PM, Goyo <goy...@gm...> wrote:

> El día 19 de abril de 2012 05:31, questions anon
> <que...@gm...> escribió:
> > Thank you, I was able to get it to work but only if I imported datetime
> > within the loop, otherwise I ended up with the
> > AttributeError: type object 'datetime.datetime' has no attribute
> 'datetime'
> > and if I added 'import datetime' at the top of my script it had an error
> > where I loop through combining each month
> > "    stop_month = datetime(2011, 03, 01)
> > TypeError: 'module' object is not callable"
>
> If you can write a standalone, minimal executable script which
> reproduces the problem I'll take a look. Send it as an attachement and
> add sample data files if necessary.
>
> Goyo
>
>
The issue is that there is a slight mixup in namespaces.  There is a module
called datetime, and that module contains a class object called datetime.
So, if your imports at the top are "import datetime", then all your
module-related stuff need to be prepended with "datetime.". But, if your
imports at the top are "from datetime import datetime", then you can use
the object freely, but you can't use anything else from the module unless
you also import it.

Here is the tricky part.  In your code, you did the following:

from datetime import datetime

If you then did:

import datetime

depending on the order the two were, one would overwrite the other.  You
can only have one thing called "datetime".  Personally, I would do one of
two things:

import datetime as dt

and use "dt.datetime()" to create datetime objects as well as call
functions like "dt.strftime()". Or, do

from datetime import datetime, date, timedelta, strftime

and get replace calls like "datetime.datetime()" and "datetime.strftime()"
with just "datetime()" and "strftime()".

I hope that clears things up.  Namespaces are a honking good idea, but
having objects be the same exact name as a module gets confusing very
easily.

Cheers!
Ben Root

Re: [Matplotlib-users] dates for x-axis

[questions a. <que...@gm...>]

thanks for all the responses. still finding it very confusing!! but got it
to work (without having to import in the loop).
I used:
from datetime import datetime as dt

but I also had to call:
from datetime import timedelta

and now it seems to work nicely. thank you


On Fri, Apr 20, 2012 at 3:36 AM, Benjamin Root <ben...@ou...> wrote:

>
>
> On Thu, Apr 19, 2012 at 1:21 PM, Goyo <goy...@gm...> wrote:
>
>> El día 19 de abril de 2012 05:31, questions anon
>> <que...@gm...> escribió:
>> > Thank you, I was able to get it to work but only if I imported datetime
>> > within the loop, otherwise I ended up with the
>> > AttributeError: type object 'datetime.datetime' has no attribute
>> 'datetime'
>> > and if I added 'import datetime' at the top of my script it had an error
>> > where I loop through combining each month
>> > "    stop_month = datetime(2011, 03, 01)
>> > TypeError: 'module' object is not callable"
>>
>> If you can write a standalone, minimal executable script which
>> reproduces the problem I'll take a look. Send it as an attachement and
>> add sample data files if necessary.
>>
>> Goyo
>>
>>
> The issue is that there is a slight mixup in namespaces.  There is a
> module called datetime, and that module contains a class object called
> datetime.  So, if your imports at the top are "import datetime", then all
> your module-related stuff need to be prepended with "datetime.". But, if
> your imports at the top are "from datetime import datetime", then you can
> use the object freely, but you can't use anything else from the module
> unless you also import it.
>
> Here is the tricky part.  In your code, you did the following:
>
> from datetime import datetime
>
> If you then did:
>
> import datetime
>
> depending on the order the two were, one would overwrite the other.  You
> can only have one thing called "datetime".  Personally, I would do one of
> two things:
>
> import datetime as dt
>
> and use "dt.datetime()" to create datetime objects as well as call
> functions like "dt.strftime()". Or, do
>
> from datetime import datetime, date, timedelta, strftime
>
> and get replace calls like "datetime.datetime()" and "datetime.strftime()"
> with just "datetime()" and "strftime()".
>
> I hope that clears things up.  Namespaces are a honking good idea, but
> having objects be the same exact name as a module gets confusing very
> easily.
>
> Cheers!
> Ben Root
>
>