I have a question that sounds simple but it's driving me mad for some days. I have a historical time series closed in two lists: the first list is containing prices, let's say P = [1, 1.5, 1.3 ...] while the second list is containing the related dates, let's say D = [01/01/2010, 02/01/2010...]. What I would like to do is to plot SOME of these dates (when I say "some" is because the "best" result I got so far is to show all of them as tickers, so creating a black cloud of unreadable data in the x-axis) that, when you zoom in, are shown more in details. This picture is now having the progressive automated range made by Matplotlib:
Instead of 0, 200, 400 etc. I would like to have the dates values that are related to the data-point plotted. Moreover, when I zoom-in I get the following:
As well as I get the detail between 0 and 200 (20, 40 etc.) I would like to get the dates attached to the list.
I'm sure this is a simple problem to solve but I'm new to Matplotlib as well as to Python and any hint would be appreciated. Thanks in advance
Matplotlib has sophisticated support for plotting dates. I'd recommend the use of AutoDateFormatter and AutoDateLocator. They are even locale-specific, so they choose month-names according to your locale.
import matplotlib.pyplot as plt
from matplotlib.dates import AutoDateFormatter, AutoDateLocator
xtick_locator = AutoDateLocator()
xtick_formatter = AutoDateFormatter(xtick_locator)
ax = plt.axes()
ax.xaxis.set_major_locator(xtick_locator)
ax.xaxis.set_major_formatter(xtick_formatter)
EDIT
For use with multiple subplots, use multiple locator/formatter pairs:
import datetime
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.dates import AutoDateFormatter, AutoDateLocator, date2num
x = [datetime.datetime.now() + datetime.timedelta(days=30*i) for i in range(20)]
y = np.random.random((20))
xtick_locator = AutoDateLocator()
xtick_formatter = AutoDateFormatter(xtick_locator)
for i in range(4):
ax = plt.subplot(2,2,i+1)
ax.xaxis.set_major_locator(xtick_locator)
ax.xaxis.set_major_formatter(xtick_formatter)
ax.plot(date2num(x),y)
plt.show()
You can do timeseries plot with pandas
For detail refer this : http://pandas.pydata.org/pandas-docs/dev/timeseries.html and
http://pandas.pydata.org/pandas-docs/dev/generated/pandas.Series.plot.html
import pandas as pd
DateStrList = ['01/01/2010','02/01/2010']
P = [2,3]
D = pd.Series([pd.to_datetime(date) for date in DateStrList])
series =pd.Series(P, index=D)
pd.Series.plot(series)
import matplotlib.pyplot as plt
import pandas
pandas.TimeSeries(P, index=D).plot()
plt.show()
Related
import pandas as pd
from datetime import datetime
import matplotlib.pyplot as plt
import numpy as np
x=pd.date_range(end=datetime.today(),periods=150,freq='W').to_pydatetime().tolist()
x_1 = np.random.rand(150)
x_2 = np.random.rand(150)/2
fig = plt.figure(figsize=(10,6),dpi=100)
ax=fig.add_subplot(111)
ax.bar(x,x_1,label='x_1')
ax.bar(x,x_2,label='x_2',bottom=x_1)
plt.legend()
plt.show()
The above code will provide this stacked bar chart.
stacked_chart1
Because the x-axis are specified as dates with 1 week apart, the distance between bars are very large.
I would like to change the chart so that the bars are next to each other with no space like the picture below.
x=np.arange(150)
x_1 = np.random.rand(150)
x_2 = np.random.rand(150)/2
fig = plt.figure(figsize=(10,6),dpi=100)
ax=fig.add_subplot(111)
ax.bar(x,x_1,label='x_1')
ax.bar(x,x_2,label='x_2',bottom=x_1)
plt.legend()
plt.show()
stacked_chart2
Except numbers as x-axis, I would still want to keep the dates in chart 1. I am wondering is there a way to do that? Thanks!!
The reason for the difference is that matplotlib will try to simplify the x-axis when you pass a datetime, because usually you cannot fit every date in the x-ticks. It doesn't try this for int or string types, which is why your second sample looks normal.
However I'm unable to figure out why in this particular example why the spacing is so odd. I looked at this post to no avail.
In any case, there are other plotting modules that tend to handle dates a little more elegantly.
import pandas as pd
from datetime import datetime
import plotly.express as px
import numpy as np
x=pd.date_range(end=datetime.today(),periods=150,freq='W').tolist()
x_1 = np.random.rand(150)
x_2 = np.random.rand(150)/2
df = pd.DataFrame({
'date':x,
'x_1':x_1,
'x_2':x_2}).melt(id_vars='date')
px.bar(df, x='date', y='value',color='variable')
Output
I have time-series plots (over 1 year) where the months on the x-axis are of the form Jan, Feb, Mar, etc, but I would like to have just the first letter of the month instead (J,F,M, etc). I set the tick marks using
ax.xaxis.set_major_locator(MonthLocator())
ax.xaxis.set_minor_locator(MonthLocator())
ax.xaxis.set_major_formatter(matplotlib.ticker.NullFormatter())
ax.xaxis.set_minor_formatter(matplotlib.dates.DateFormatter('%b'))
Any help would be appreciated.
The following snippet based on the official example here works for me.
This uses a function based index formatter order to only return the first letter of the month as requested.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab
import matplotlib.cbook as cbook
import matplotlib.ticker as ticker
datafile = cbook.get_sample_data('aapl.csv', asfileobj=False)
print 'loading', datafile
r = mlab.csv2rec(datafile)
r.sort()
r = r[-365:] # get the last year
# next we'll write a custom formatter
N = len(r)
ind = np.arange(N) # the evenly spaced plot indices
def format_date(x, pos=None):
thisind = np.clip(int(x+0.5), 0, N-1)
return r.date[thisind].strftime('%b')[0]
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(ind, r.adj_close, 'o-')
ax.xaxis.set_major_formatter(ticker.FuncFormatter(format_date))
fig.autofmt_xdate()
plt.show()
I tried to make the solution suggested by #Appleman1234 work, but since I, myself, wanted to create a solution that I could save in an external configuration script and import in other programs, I found it inconvenient that the formatter had to have variables defined outside of the formatter function itself.
I did not solve this but I just wanted to share my slightly shorter solution here so that you and maybe others can take it or leave it.
It turned out to be a little tricky to get the labels in the first place, since you need to draw the axes, before the tick labels are set. Otherwise you just get empty strings, when you use Text.get_text().
You may want to get rid of the agrument minor=True which was specific to my case.
# ...
# Manipulate tick labels
plt.draw()
ax.set_xticklabels(
[t.get_text()[0] for t in ax.get_xticklabels(minor=True)], minor=True
)
I hope it helps:)
The original answer uses the index of the dates. This is not necessary. One can instead get the month names from the DateFormatter('%b') and use a FuncFormatter to use only the first letter of the month.
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.ticker import FuncFormatter
from matplotlib.dates import MonthLocator, DateFormatter
x = np.arange("2019-01-01", "2019-12-31", dtype=np.datetime64)
y = np.random.rand(len(x))
fig, ax = plt.subplots()
ax.plot(x,y)
month_fmt = DateFormatter('%b')
def m_fmt(x, pos=None):
return month_fmt(x)[0]
ax.xaxis.set_major_locator(MonthLocator())
ax.xaxis.set_major_formatter(FuncFormatter(m_fmt))
plt.show()
I folks,
Consider the following example
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
fig, (ax1,ax2) = plt.subplots(2,1)
dates = pd.date_range("2018-01-01","2019-01-01",freq = "1d")
x = pd.DataFrame(index = dates, data = np.linspace(0,1,len(dates)) )
x.plot(ax=ax1)
y = np.random.random([len(dates),100]) * x.values
ax2.pcolormesh(range(len(x)), np.linspace(-1,1,100), y.T)
plt.show()
At this point, I would like the both axis (ax1,ax2) to share the x-axis, i.e. displaying proper pandas dates on the second axis. sharex=True does not seem to work. How can I achieve that? I tried different possibilities which did not work out.
Edit: Since the pandas date formatting is superior to the native matplotlib formatting, please provide me with a solution where pandas date formatting is used (for instance, zooming with an interactive environment works much better with pandas date formatting). Thanks You!
One way to do it would be to do all the plotting with matplotlib, this way there are no problems with the different time formats being used:
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
fig, (ax1,ax2) = plt.subplots(2,1, sharex='col')
dates = pd.date_range("2018-01-01","2019-01-01",freq = "1d")
x = pd.DataFrame(index = dates, data = np.linspace(0,1,len(dates)) )
#x.plot(ax=ax1)
ax1.plot(x.index, x.values)
y = np.random.random([len(dates),100]) * x.values
ax2.pcolormesh(x.index, np.linspace(-1,1,100), y.T)
fig.tight_layout()
plt.show()
This gives the following plot:
What seems to work fine is to first plot the same line into the axes that should host the image, then plot the image, then remove the line again. What this does is that it tells pandas to apply its locators and formatters to that axes; they will stay after removing the line.
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np
fig, (ax1,ax2) = plt.subplots(2,1, sharex=True)
dates = pd.date_range("2018-01-01","2019-01-01",freq = "1d")
x = pd.DataFrame(index = dates, data = np.linspace(0,1,len(dates)) )
x.plot(ax=ax1)
y = np.random.random([len(dates),100]) * x.values
x.plot(ax=ax2, legend=False)
ax2.pcolormesh(dates, np.linspace(-1,1,100), y.T)
ax2.lines[0].remove()
plt.show()
Note that there may be caveats of this solution when zooming or panning. Consider it more like a hack and use it as long as it works, but don't blame anyone once it doesn't.
I'm hoping to create a line graph which shows the changes to flowering and fruiting times (phenophases) from year to year. For each phenophase I'd like to plot the average Day of Year and, if possible, show the min and max for each year as an error bar. I've filtered down all the data I need in a few data frames, grouped it all in a sensible way, but I can't figure out how to get it all to plot. Here's a screen grab of where I'm at: Imgur
All the examples I've found adding error bars have been based on formulas or other equal amounts over/under, but in my case the max/min will be different so I'm not sure how to integrate that. Possible just create a list of each column's data and feed that to plot? I'm playing with that now but not getting far.
Also, if anyone has general suggestions as to better ways to present this data I'm all ears. I've looked into Gantt plots but didn't get far with them, as this seems a bit more straight-forward just using matplotlib. I'm happy to put some demo data or the rest of my notebook up if anyone thinks that would help.
Edit: Here's some sample data and the code from my notebook: Gist
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.ticker as ticker
%matplotlib inline
pd.set_option('display.max_columns', 40)
tick_spacing = 1
dfClean = df[['Site_Cluster', 'Species', 'Phenophase_Name',
'Phenophase_Status', 'Observation_Year', 'Day_of_Year']]
dfClean = dfClean[dfClean.Phenophase_Status == 1]
PhenoNames = ['Open flowers', 'Ripe fruits']
dfLakes = dfClean[(dfClean.Phenophase_Name.isin(PhenoNames))
& (dfClean.Site_Cluster == 'Lakes')
& (dfClean.Species == 'lapponica')]
dfLakesGrouped = dfLakes.groupby(['Observation_Year', 'Phenophase_Name'])
dfLakesReady = dfLakesGrouped.Day_of_Year.agg([np.min, np.mean, np.max]).round(0)
dfLakesReady = dfLakesReady.unstack()
print(dfLakesReady['mean'].plot())
Here's another answer:
from pandas import DataFrame, date_range, Timedelta
import numpy as np
from matplotlib import pyplot as plt
rng = date_range(start='2015-01-01', periods=5, freq='24H')
df = DataFrame({'y':np.random.normal(size=len(rng))}, index=rng)
y1 = df['y']
y2 = (y1*3)
sd1 = (y1*2)
sd2 = (y1*2)
fig,(ax1,ax2) = plt.subplots(2,1,sharex=True)
_ = y1.plot(yerr=sd1, ax=ax1)
_ = y2.plot(yerr=sd2, ax=ax2)
Output:
How can I format the x-axis so that the spacing between periods is "to scale". As in, the distance between 10yr and 30yr should be much larger than the distance between 1yr and 2yr.
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import Quandl as ql
yield_ = ql.get("USTREASURY/YIELD")
today = yield_.iloc[-1,:]
month_ago = yield_.iloc[-1000,:]
df = pd.concat([today, month_ago], axis=1)
df.columns = ['today', 'month_ago']
df.plot(style={'today': 'ro-', 'month_ago': 'bx--'},title='Treasury Yield Curve, %');
plt.show()
I want my chart to look like this...
I think doing this while staying purely within Pandas might be tricky. You first need to create a new matplotlib figure and axe. The following might not work exactly but will give you a good idea.
df['years']=[1/12.,0.25,0.5,1,2,3,5,7,10,20,30]
fig = plt.figure()
ax = fig.add_subplot(1,1,1)
df.plot(x='years',y='today',ax=ax,kind='scatter')
df.plot(x='years',y='month_ago',ax=ax,kind='scatter')
plt.show()
If you want your axe labels to look like your chart you'll also need to set the lower and upper limit of your axis so they look good and then do something like:
ax.set_xticklabels(list(df.index))