I am new to Python and learning data visualization using matplotlib.
I am trying to plot Date/Time vs Values using matplotlib from this CSV file:
https://drive.google.com/file/d/1ex2sElpsXhxfKXA4ZbFk30aBrmb6-Y3I/view?usp=sharing
Following is the code snippet which I have been playing around with:
import pandas as pd
from matplotlib import pyplot as plt
import matplotlib.dates as mdates
plt.style.use('seaborn')
years = mdates.YearLocator()
months = mdates.MonthLocator()
days = mdates.DayLocator()
hours = mdates.HourLocator()
minutes = mdates.MinuteLocator()
years_fmt = mdates.DateFormatter('%H:%M')
data = pd.read_csv('datafile.csv')
data.sort_values('Date/Time', inplace=True)
fig, ax = plt.subplots()
ax.plot('Date/Time', 'Discharge', data=data)
# format the ticks
ax.xaxis.set_major_locator(minutes)
ax.xaxis.set_major_formatter(years_fmt)
ax.xaxis.set_minor_locator(hours)
datemin = min(data['Date/Time'])
datemax = max(data['Date/Time'])
ax.set_xlim(datemin, datemax)
ax.format_xdata = mdates.DateFormatter('%Y.%m.%d %H:%M')
ax.format_ydata = lambda x: '%1.2f' % x # format the price.
ax.grid(True)
fig.autofmt_xdate()
plt.show()
The code is plotting the graph but it is not labeling the X-Axis and also giving some unknown values (on mouse over) for x on the bottom right corner as shown in the below screenshot:
Screenshot of matplotlib figure window
Can someone please suggest what changes are needed to plot the x-axis dates and also make the correct values appear when I move the cursor over the graph?
Thanks
I haven't used matplotlib. Instead I used pandas plotting
import pandas as pd
data = pd.read_csv('datafile.csv')
data.sort_values('Date/Time', inplace=True)
data["Date/Time"] = pd.to_datetime(data["Date/Time"], format="%d.%m.%Y %H:%M")
ax = data.plot.line(x='Date/Time', y='Discharge')
Here, you need to convert the Date/Time to pandas datetime type.
The main issue you have there is that the date formats are mixed up - your data uses '%d.%m.%Y %H:%M', but you set '%Y.%m.%d %H:%M' and this is why you saw 'rubbish' values in x ticks labels. Anyway the number of lines in your code can be reduced heavily if you convert your Date/Time column to timestamps, ie.:
import pandas as pd
from matplotlib import pyplot as plt
import matplotlib.dates as mdates
plt.style.use('seaborn')
data = pd.read_csv('datafile.csv')
data.sort_values('Date/Time', inplace=True)
data["Date/Time"] = pd.to_datetime(data["Date/Time"], format="%d.%m.%Y %H:%M")
data.sort_values('Date/Time', inplace=True)
fig, ax = plt.subplots()
ax.plot('Date/Time', 'Discharge', data=data)
ax.format_xdata = mdates.DateFormatter('%Y.%m.%d %H:%M')
ax.tick_params(axis='x', rotation=45)
ax.grid(True)
fig.autofmt_xdate()
plt.show()
Note that the format of labels in the plot will depend on the zoom level, so you will need to enlarge a portion of the graph to see hours and minutes in the tick labels, but the cursor locator on the bottom bar of the window should be always displaying the detailed timestamp under the cursor.
Related
I wonder if it's possible to change the measurement milestones for graphs created by pandas. In my code the X-axis stands for time and is measured by month, but the measurement milestones are all over the place.
In the image below, the milestones for the X-axis are 2012M01, 2012M06, 2012M11, 2013M04 and 2013M09.
Is there any way I can choose how long the distance should be between every milestone? For example, to make it so it shows every year or every half year?
This is the code I used for the function making the graph:
def graph(dataframe):
graph = dataframe[["Profit"]].plot()
graph.set_title('Statistics')
graph.set_ylabel('Thousand $')
graph.set_xlabel('Time')
plt.grid(True)
plt.show()
The actual dataframe is just an excel-file with a bunch of months and monetary values in it.
I think the most straight forward is to use matplotlib.dates to format the axis:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
def graph(dataframe):
fig, ax = plt.subplots()
xfmt = mdates.DateFormatter('%YM%m') #see https://strftime.org/
major = mdates.MonthLocator([1,7]) #label only Jan and Jul
graph = dataframe[["Profit"]].plot(ax=ax) #link plot to the existing axes
graph.set_title('Statistics')
graph.set_ylabel('Thousand $')
graph.set_xlabel('Time')
graph.xaxis.set_major_locator(major) #set major locator tick on x-axis
graph.xaxis.set_major_formatter(xfmt) #format xtick label
plt.grid(True)
plt.show()
But a key point is you need to have your dates as Python's built-in datetime.date (not datetime.datetime); thanks to this answer. If your dates are str or a different type of datetime, you will need to convert, but there are many resources on SO and elsewhere for doing this like this or this:
In[0]:
dr = pd.date_range('01-01-2012', '01-01-2014', freq='1MS')
dr = [pd.to_datetime(date).date() for date in df.index] #explicitly converting to datetime with .date()
df = pd.DataFrame(index=dr, data={'Profit':np.random.rand(25)})
type(df.index.[0])
Out[0]:
datetime.date
Calling graph(df) using the example above gets this plot:
Just to expand on this, here's what happens when the index is pandas.Timestamp instead of datetime.date:
In[0]:
dr = pd.date_range('01-01-2012', '01-01-2014', freq='1MS')
# dr = [pd.to_datetime(date).date() for date in df.index] #skipping date conversion
df = pd.DataFrame(index=dr, data={'Profit':np.random.rand(25)})
graph(df)
Out[0]:
The x-axis is improperly formatted:
However, if you are willing to just create the plot directly through matplotlib, rather than pandas (pandas is using matplotlib anyway), this can handle more types of dates:
In[0]:
dr = pd.date_range('01-01-2012', '01-01-2014', freq='1MS')
# dr = [pd.to_datetime(date).date() for date in df.index] #skipping date conversion
df = pd.DataFrame(index=dr, data={'Profit':np.random.rand(25)})
def graph_2(dataframe):
fig, ax = plt.subplots()
xfmt = mdates.DateFormatter('%YM%m')
major = mdates.MonthLocator([1,7])
ax.plot(dataframe.index,dataframe['Profit'], label='Profit')
ax.set_title('Statistics')
ax.set_ylabel('Thousand $')
ax.set_xlabel('Time')
ax.xaxis.set_major_locator(major)
ax.xaxis.set_major_formatter(xfmt)
ax.legend() #legend needs to be added
plt.grid(True)
plt.show()
graph_2(df)
type(df.index[0])
Out[0]:
pandas._libs.tslibs.timestamps.Timestamp
And here is the working graph:
I am plotting values from a dataframe where time is the x-axis. The time is formatted as 00:00 to 23:45. I only want to display the specific times 00:00, 06:00, 12:00, 18:00 on the x-axis of my plot. How can this be done? I have posted two figures, the first shows the format of my dataframe after setting the index to time. And the second shows my figure. Thank you for your help!
monday.set_index("Time", drop=True, inplace=True)
monday_figure = monday.plot(kind='line', legend = False,
title = 'Monday Average Power consumption')
monday_figure.xaxis.set_major_locator(plt.MaxNLocator(8))
Edit: Adding data as text:
Time,DayOfWeek,kW
00:00:00,Monday,5.8825
00:15:00,Monday,6.0425
00:30:00,Monday,6.0025
00:45:00,Monday,5.7475
01:00:00,Monday,6.11
01:15:00,Monday,5.8025
01:30:00,Monday,5.6375
01:45:00,Monday,5.85
02:00:00,Monday,5.7250000000000005
02:15:00,Monday,5.66
02:30:00,Monday,6.0025
02:45:00,Monday,5.71
03:00:00,Monday,5.7425
03:15:00,Monday,5.6925
03:30:00,Monday,5.9475
03:45:00,Monday,6.380000000000001
04:00:00,Monday,5.65
04:15:00,Monday,5.8725
04:30:00,Monday,5.865
04:45:00,Monday,5.71
05:00:00,Monday,5.6925
05:15:00,Monday,5.9975000000000005
05:30:00,Monday,5.905000000000001
05:45:00,Monday,5.93
06:00:00,Monday,5.6025
06:15:00,Monday,6.685
06:30:00,Monday,7.955
06:45:00,Monday,8.9225
07:00:00,Monday,10.135
07:15:00,Monday,12.9475
07:30:00,Monday,14.327499999999999
07:45:00,Monday,14.407499999999999
08:00:00,Monday,15.355
08:15:00,Monday,16.2175
08:30:00,Monday,18.355
08:45:00,Monday,18.902499999999996
09:00:00,Monday,19.0175
09:15:00,Monday,20.0025
09:30:00,Monday,20.355
09:45:00,Monday,20.3175
10:00:00,Monday,20.8025
10:15:00,Monday,20.765
10:30:00,Monday,21.07
10:45:00,Monday,19.9825
11:00:00,Monday,20.94
11:15:00,Monday,22.1325
11:30:00,Monday,20.6275
11:45:00,Monday,21.4475
12:00:00,Monday,22.092499999999998
The image above is produced using the code from the comment below.
Make sure you have a datetime index using pd.to_datetime when plotting timeseries.
I then used matplotlib.mdates to detect the desired ticks and format them in the plot. I don't know if it can be done from pandas with df.plot.
See matplotlib date tick labels. You can customize the HourLocator or use a different locator to suit your needs. Minor ticks are created the same way with ax.xaxis.set_minor_locator. Hope it helps.
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
# Using your dataframe
df = pd.read_clipboard(sep=',')
# Make sure you have a datetime index
df['Time'] = pd.to_datetime(df['Time'])
df = df.set_index('Time')
fig, ax = plt.subplots(1,1)
ax.plot(df['kW'])
# Use mdates to detect hours
locator = mdates.HourLocator(byhour=[0,6,12,18])
ax.xaxis.set_major_locator(locator)
# Format x ticks
formatter = mdates.DateFormatter('%H:%M:%S')
ax.xaxis.set_major_formatter(formatter)
# rotates and right aligns the x labels, and moves the bottom of the axes up to make room for them
fig.autofmt_xdate()
I've been trying to plot my data on a line chart, and I expect it to show dates on the horizontal axis, i used index_col to set the index as date but that returns an empty dataframe.. can some one help please
data = pd.read_csv('good_btc_dataset.csv', warn_bad_lines= True,
index_col= ['date'])
data.dropna(inplace=True)
data.index = range(3169)
data.head()
I expect my chart to show dates on the horizontal axis but all it shows is numbers
thanks in advance
I recommend you to check this script (it is a copy and paste from the documentation). I think you just need to adapt your own data.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import matplotlib.cbook as cbook
years = mdates.YearLocator() # every year
months = mdates.MonthLocator() # every month
years_fmt = mdates.DateFormatter('%Y')
# Load a numpy structured array from yahoo csv data with fields date, open,
# close, volume, adj_close from the mpl-data/example directory. This array
# stores the date as an np.datetime64 with a day unit ('D') in the 'date'
# column.
with cbook.get_sample_data('goog.npz') as datafile:
data = np.load(datafile)['price_data']
fig, ax = plt.subplots()
ax.plot('date', 'adj_close', data=data)
# format the ticks
ax.xaxis.set_major_locator(years)
ax.xaxis.set_major_formatter(years_fmt)
ax.xaxis.set_minor_locator(months)
# round to nearest years.
datemin = np.datetime64(data['date'][0], 'Y')
datemax = np.datetime64(data['date'][-1], 'Y') + np.timedelta64(1, 'Y')
ax.set_xlim(datemin, datemax)
# format the coords message box
ax.format_xdata = mdates.DateFormatter('%Y-%m-%d')
ax.format_ydata = lambda x: '$%1.2f' % x # format the price.
ax.grid(True)
# rotates and right aligns the x labels, and moves the bottom of the
# axes up to make room for them
fig.autofmt_xdate()
plt.show()
I am trying to manually create a candlestick chart with matplotlib using errorbar for the daily High and Low prices and Rectangle() for the Adjusted Close and Open prices. This question seemed to have all the prerequisites for accomplishing this.
I attempted to use the above very faithfully, but the issue of plotting something over an x-axis of datetime64[ns]'s gave me no end of errors, so I've additionally tried to incorporate the advice here on plotting over datetime.
This is my code so far, with apologies for the messiness:
import pandas as pd
import datetime as dt
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
from matplotlib.collections import PatchCollection
from matplotlib.patches import Rectangle
def makeCandles(xdata,high,low,adj_close,adj_open,fc='r',ec='None',alpha=0.5):
## Converting datetimes to numerical format matplotlib can understand.
dates = mdates.date2num(xdata)
## Creating default objects
fig,ax = plt.subplots(1)
## Creating errorbar peaks based on high and low prices
avg = (high + low) / 2
err = [high - avg,low - avg]
ax.errorbar(dates,err,fmt='None',ecolor='k')
## Create list for all the error patches
errorboxes = []
## Loop over data points; create "body" of candlestick
## based on adjusted open and close prices
errors=np.vstack((adj_close,adj_open))
errors=errors.T
for xc,yc,ye in zip(dates,avg,errors):
rect = Rectangle((xc,yc-ye[0]),1,ye.sum())
errorboxes.append(rect)
## Create patch collection with specified colour/alpha
pc = PatchCollection(errorboxes,facecolor=fc,alpha=alpha,edgecolor=ec)
## Add collection to axes
ax.add_collection(pc)
plt.show()
With my data looking like
This is what I try to run, first getting a price table from quandl,
import quandl as qd
api = '1uRGReHyAEgwYbzkPyG3'
qd.ApiConfig.api_key = api
data = qd.get_table('WIKI/PRICES', qopts = { 'columns': ['ticker', 'date', 'high','low','adj_open','adj_close'] }, \
ticker = ['AMZN', 'XOM'], date = { 'gte': '2014-01-01', 'lte': '2016-12-31' })
data.reset_index(inplace=True,drop=True)
makeCandles(data['date'],data['high'],data['low'],data['adj_open'],data['adj_close'])
The code runs with no errors, but outputs an empty graph. So what I am asking for is advice on how to plot these rectangles over the datetime dates. For the width of the rectangles, I simply put a uniform "1" bec. I am not aware of a simple way to specify the datetime width of a rectangle.
Edit
This is the plot I am currently getting, having transformed my xdata into matplotlib mdates:
Before I transformed xdata via mdates, with just xdata as my x-axis everywhere, this was one of the errors I kept getting:
To get the plot you want, there's a couple of things that need to be considered. First you're retrieving to stocks AMZN and XOM, displaying both will make the chart you want look funny, because the data are quite far apart. Second, candlestick charts in which you plot each day for several years will get very crowded. Finally, you need to format your ordinal dates back on the x-axis.
As mentioned in the comments, you can use the pre-built matplotlib candlestick2_ohlc function (although deprecated) accessible through mpl_finance, install as shown in this answer. I opted for using solely the matplotlib barchart with built-in errorbars.
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import quandl as qd
from matplotlib.dates import DateFormatter, WeekdayLocator, \
DayLocator, MONDAY
# get data
api = '1uRGReHyAEgwYbzkPyG3'
qd.ApiConfig.api_key = api
data = qd.get_table('WIKI/PRICES', qopts={'columns': ['ticker', 'date', 'high', 'low', 'open', 'close']},
ticker=['AMZN', 'XOM'], date={'gte': '2014-01-01', 'lte': '2014-03-10'})
data.reset_index(inplace=True, drop=True)
fig, ax = plt.subplots(figsize = (10, 5))
data['date'] = mdates.date2num(data['date'].dt.to_pydatetime()) #convert dates to ordinal
tickers = list(set(data['ticker'])) # unique list of stock names
for stock_ind in tickers:
df = data[data['ticker'] == 'AMZN'] # select one, can do more in a for loop, but it will look funny
inc = df.close > df.open
dec = df.open > df.close
ax.bar(df['date'][inc],
df['open'][inc]-df['close'][inc],
color='palegreen',
bottom=df['close'][inc],
# this yerr is confusing when independent error bars are drawn => (https://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.errorbar)
yerr = [df['open'][inc]-df['high'][inc], -df['open'][inc]+df['low'][inc]],
error_kw=dict(ecolor='gray', lw=1))
ax.bar(df['date'][dec],
df['close'][dec]-df['open'][dec],
color='salmon', bottom=df['open'][dec],
yerr = [df['close'][dec]-df['high'][dec], -df['close'][dec]+df['low'][dec]],
error_kw=dict(ecolor='gray', lw=1))
ax.set_title(stock_ind)
#some tweaking, setting the dates
mondays = WeekdayLocator(MONDAY) # major ticks on the mondays
alldays = DayLocator() # minor ticks on the days
weekFormatter = DateFormatter('%b %d') # e.g., Jan 12
dayFormatter = DateFormatter('%d') # e.g., 12
ax.xaxis.set_major_locator(mondays)
ax.xaxis.set_minor_locator(alldays)
ax.xaxis.set_major_formatter(weekFormatter)
ax.set_ylabel('monies ($)')
plt.show()
I'm trying to build matplotlib charts whose x-axis is a dateIndex from a pandas dataframe. Trying to mimic some examples from matplotlib, I've been unsuccessful. The xaxis ticks and labels never appear.
I thought maybe matplotlib wasn't properly digesting the pandas index, so I converted it to ordinal with the matplotlib date2num helper function, but that gave the same result.
# https://matplotlib.org/api/dates_api.html
# https://matplotlib.org/examples/api/date_demo.html
import datetime as dt
import matplotlib.dates as mdates
import matplotlib.cbook as cbook
import matplotlib.dates as mpd
years = mdates.YearLocator() # every year
months = mdates.MonthLocator() # every month
yearsFmt = mdates.DateFormatter('%Y')
majorLocator = years
majorFormatter = yearsFmt #FormatStrFormatter('%d')
minorLocator = months
y1 = np.arange(100)*0.14+1
y2 = -(np.arange(100)*0.04)+12
"""neither of these indices works"""
x = pd.date_range(start='4/1/2012', periods=len(y1))
#x = map(mpd.date2num, pd.date_range(start='4/1/2012', periods=len(y1)))
fig, ax = plt.subplots()
ax.plot(x,y1)
ax.plot(x,y2)
ax.xaxis.set_major_locator(years)
ax.xaxis.set_major_formatter(yearsFmt)
ax.xaxis.set_minor_locator(months)
datemin = x[0]
datemax = x[-1]
ax.set_xlim(datemin, datemax)
fig.autofmt_xdate()
plt.show()
The problem is the following. pd.date_range(start='4/1/2012', periods=len(y1)) creates dates from the first of April 2012 to the 9th of July 2012.
Now you set the major locator to be a YearLocator. This means, that you want to have a tick for each year on the axis. However, all dates are within the same year 2012. So there is no major tick to be shown within the plot range.
The suggestion would be to use a MonthLocator instead, such that the first of each month is ticked. Also if would make sense to use a formatter, which actually shows the months, e.g. '%b %Y'. You may use a DayLocator for the minor ticks, if you want, to show the small tickmarks for each day.
ax.xaxis.set_major_locator(mdates.MonthLocator())
ax.xaxis.set_major_formatter(mdates.DateFormatter('%b %Y'))
ax.xaxis.set_minor_locator(mdates.DayLocator())
Complete example:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
y1 = np.arange(100)*0.14+1
y2 = -(np.arange(100)*0.04)+12
x = pd.date_range(start='4/1/2012', periods=len(y1))
fig, ax = plt.subplots()
ax.plot(x,y1)
ax.plot(x,y2)
ax.xaxis.set_major_locator(mdates.MonthLocator())
ax.xaxis.set_major_formatter(mdates.DateFormatter('%b %Y'))
ax.xaxis.set_minor_locator(mdates.DayLocator())
fig.autofmt_xdate()
plt.show()
You could use pd.DataFrame.plot to handle most of that
df = pd.DataFrame(dict(
y1=y1, y2=y2
), index=x)
df.plot()