How to plot numpy arrays in pandas dataframe

Question

I have the DataFrame:

df = 

sample_type         observed_data
     A          [0.2, 0.5, 0.17, 0.1]
     A          [0.9, 0.3, 0.24, 0.5]
     A          [0.9, 0.5, 0.6, 0.39]
     B          [0.01, 0.07, 0.15, 0.26]
     B          [0.08, 0.14, 0.32, 0.58]
     B          [0.01, 0.16, 0.42, 0.41]

where the data type in the observed_data column is np.array. What's the easiest and most efficient way of plotting each of the numpy arrays overlayed on the same plot using matplotlib and/or plotly and showing A and B as separate colors or line types (eg. dashed, dotted, etc.)?

Redox · Accepted Answer · 2022-09-29 05:59:13Z

3

You can use this...

df = pd.DataFrame({'sample_type' : ['A', 'A', 'A', 'B', 'B', 'B'], 
                   'observed_data' : [[0.2, 0.5, 0.17, 0.1], [0.9, 0.3, 0.24, 0.5], [0.9, 0.5, 0.6, 0.39], 
                                      [0.01, 0.07, 0.15, 0.26], [0.08, 0.14, 0.32, 0.58], [0.01, 0.16, 0.42, 0.41]]})

for ind, cell in df['observed_data'].iteritems():
    if len(cell) > 0:
        if df.loc[ind,'sample_type'] == 'A':
            plotted = plt.plot(np.linspace(0,1,len(cell)), cell, color='blue', marker = 'o', linestyle = '-.')
        else:
            plotted = plt.plot(np.linspace(0,1,len(cell)), cell, color='red', marker = '*', linestyle = ':')
plt.show()

answered Sep 29, 2022 at 5:59

Redox

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4 Comments

MAtennis9 Over a year ago

was the reasoning for using np.linspace just because it fully covered the range of values in observed_data? If new values >1 need to be plotted, how can I amend the code above to just plot the numpy arrays regardless of the range of values?

Redox Over a year ago

The use of linspace is just to give the plot an x-axis which is equally spaced. Note that it has len(each_array) inside. You can change it from 0-1 or 0-23 or 0-100 or anything you like.... the x-axis will show the same range. If you don't need the x-ticklabels, it can beh hidden. What do you mean by new value > 1?

MAtennis9 Over a year ago

couldn't I just do plt.plot(cell, color='blue', marker = 'o', linestyle = '-.') without specifying the x-axis range?

Redox Over a year ago

I think you can, have you tried it? Think the x-axis tick labels might change. See if that works for you. If you don't care about the x-axis, you can hide it using plt.gca().axes.xaxis.set_visible(False)

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