Changing the xlim by date in Matplotlib

Question

I am trying to make a visually appealing graph in Python. I was using Randal Olson's example http://www.randalolson.com/2014/06/28/how-to-make-beautiful-data-visualizations-in-python-with-matplotlib/ here and trying to make some adjustments.

My data is simple,

dispute_percentage
Out[34]: 

2015-08-11    0.017647
2015-08-12    0.004525
2015-08-13    0.006024
2015-08-14    0.000000
2015-08-15    0.000000
2015-08-17    0.000000

The problem is that the data starts loading at Feb 2015, and I want to start displaying at April 2015.

Here is my code

from __future__ import division
from collections import OrderedDict
import pandas as pd
from collections import Counter
from pylab import * 
import datetime as datetime 
dispute_percentage.plot(kind = 'line')
plt.xlabel('Date')
plt.ylabel('Percent')
plt.title('Percent Disputes In FY2015')

# Remove the plot frame lines. They are unnecessary chartjunk.    
ax = plt.subplot(111)    
ax.spines["top"].set_visible(False)    
ax.spines["bottom"].set_visible(False)    
ax.spines["right"].set_visible(False)    
ax.spines["left"].set_visible(False) 


# Ensure that the axis ticks only show up on the bottom and left of the plot.    
# Ticks on the right and top of the plot are generally unnecessary chartjunk.    
ax.get_xaxis().tick_bottom()    
#ax.get_yaxis().tick_left()    

# Limit the range of the plot to only where the data is.    
# Avoid unnecessary whitespace.   
datenow = datetime.datetime.now
dstart = datetime(2015,4,1)
print datenow 
plt.ylim(0, .14)    
plt.xlim(dstart, datenow)    

The xlim is what I am struggling with. I'm getting the error

File "C:/Mypath/name.py", line 52, in <module>
    dstart = datetime(2015,4,1)

TypeError: 'module' object is not callable

If anyone could help with this that would be great. Also any input on trying to make it prettier would also be appreciated.

Solution

You need to call datetime.datetime.now() with the parentheses on the end, and for dstart, you need to use the datetime method of the datetime module: datetime.datetime(2015,4,1)

import datetime

datenow = datetime.datetime.now()
dstart = datetime.datetime(2015,4,1)

EDIT: To set the xticks to the first of the month (thanks to @AndyKubiak):

firsts=[]
for i in range(dstart.month, datenow.month+1):
    firsts.append(datetime.datetime(2015,i,1)) 
plt.xticks(firsts)

Comments

[jenryb]

Thanks for the answer. Is there a way to only list the first of the month? I am getting labels April 08, April 29, May 20, July 01, etc.

[Andy Kubiak]

firsts = []; for i in range(1, 13): firsts.append(datetime.datetime(2015, i, 1))

[tmdavison]

@jenryb: See me edit, which uses the method from @AndyKubiak (but limits the xticks to your dstart to datenow range)

[jenryb]

@tom This worked well, thank you. I would just change "first" to "firsts" in the middle line and a parenthesis to the end of the middle line as well and it works perfectly.