- #120 Basic line chart
- # 120 Basic line chart
- #120 Basic line chart
A line chart or line graph is a type of chart which displays information as a series of data points called ‘markers’ connected by straight line segments. It is similar to a scatter plot except that the measurement points are ordered (typically by their x-axis value) and joined with straight line segments.
- Basic lineplot
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This post describes how the plot function of matplotlib works. If you give only a serie of values, matplotlib will consider that these values are ordered and will use values from 1 to n to create the X axis (figure 1):
# libraries import matplotlib.pyplot as plt import numpy as np # create data values=np.cumsum(np.random.randn(1000,1)) # use the plot function plt.plot(values)
- Seaborn customization
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For a more trendy look, just load the seaborn library. You will automatically get the look of figure 2.
# libraries import matplotlib.pyplot as plt import numpy as np import seaborn as sns # create data values=np.cumsum(np.random.randn(1000,1)) # use the plot function plt.plot(values)
- Use lineplot with ordered data !
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Of course you can make a line chart from 2 series of values (X and Y axis). However, make sure that your X axis values are ordered! If not you will get this kind of figure (figure 3).
# libraries and data import matplotlib.pyplot as plt import numpy as np import seaborn as sns import pandas as pd df=pd.DataFrame({'xvalues': range(1,101), 'yvalues': np.random.randn(100) }) # plot plt.plot( 'xvalues', 'yvalues', data=df) plt.show()
- Use lineplot with ordered data !
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If your X data are ordered, then you will get the same figure than figure 1:
# libraries import matplotlib.pyplot as plt import seaborn as sns # import the iris dataset df = sns.load_dataset('iris') # plot plt.plot( 'sepal_width', 'sepal_length', data=df) plt.show()
I am getting this error:
Traceback (most recent call last):
File “map.py”, line 9, in
plt.plot(values)
File “/usr/local/lib/python3.5/dist-packages/matplotlib/pyplot.py”, line 3229, in plot
ax = gca()
File “/usr/local/lib/python3.5/dist-packages/matplotlib/pyplot.py”, line 959, in gca
return gcf().gca(**kwargs)
File “/usr/local/lib/python3.5/dist-packages/matplotlib/pyplot.py”, line 588, in gcf
return figure()
File “/usr/local/lib/python3.5/dist-packages/matplotlib/pyplot.py”, line 534, in figure
**kwargs)
File “/usr/local/lib/python3.5/dist-packages/matplotlib/backend_bases.py”, line 170, in new_figure_manager
return cls.new_figure_manager_given_figure(num, fig)
File “/usr/local/lib/python3.5/dist-packages/matplotlib/backends/backend_tkagg.py”, line 1049, in new_figure_manager_given_figure
window = Tk.Tk(className=”matplotlib”)
File “/usr/lib/python3.5/tkinter/__init__.py”, line 1871, in __init__
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: no display name and no $DISPLAY environment variable
Hi Joshua, I checked with both Python 2 and Python 3 and it works for me. Plus your error message is quite obscur. Did you simply copy and paste the code in the python console?
You just need some sort of a graphical environment to run it properly. It can’t display a chart in console 🙂