[FIXED] Matplotlib eventplot - raster plot from binary values

Issue

I have created a dataframe where each column is an equal-length series of 1.0s and 0.0s. There is nothing else in the dataframe. I want to create a raster-style plot from this data where each column would be a horizontal line stacked up along the y-axis and each tick on the x-axis would correspond to a row index value.

However, when I try to do this, I get an "axis -1 is out of bounds for array of dimension 0" error. None of the other entries for this or very similar errors seem to relate to eventplot. I thought the type of data I had would be perfect for eventplot (a discrete black dash wherever there's a 1.0, otherwise nothing), but maybe I'm very wrong.

Here's a toy example of the kind of dataframe I'm trying to pass plus the function as I'm calling it:

    SP1     SP3     SP5     SP7     SP9     SP11
0   1.0     0.0     0.0     0.0     0.0     0.0
1   0.0     0.0     0.0     1.0     0.0     0.0
2   0.0     0.0     0.0     0.0     0.0     0.0
3   0.0     1.0     0.0     0.0     0.0     0.0
4   0.0     0.0     1.0     0.0     1.0     0.0
5   0.0     1.0     0.0     0.0     1.0     1.0


plt.eventplot(df, colors='black', lineoffsets=1,
                    linelengths=1, orientation='vertical')

Any help appreciated, thank you.

Edit: If I convert my df into an np.array and pass that instead, I no longer get that particular error, but I don't at all get the result I'm looking for. I do get the correct values on the x-axis (in my real data, this is 0-22), but I don't get each column of data represented as a separate line, and I'm having no luck advancing in that direction.

Solution

When using eventplot, the array passed to positions needs to contain the row numbers of the ones in each column. Here is an example with your toy data:

import io
import pandas as pd              # v 1.2.3
import matplotlib.pyplot as plt  # v 3.3.4

# Import data into dataframe
data = """
SP1     SP3     SP5     SP7     SP9     SP11
0   1.0     0.0     0.0     0.0     0.0     0.0
1   0.0     0.0     0.0     1.0     0.0     0.0
2   0.0     0.0     0.0     0.0     0.0     0.0
3   0.0     1.0     0.0     0.0     0.0     0.0
4   0.0     0.0     1.0     0.0     1.0     0.0
5   0.0     1.0     0.0     0.0     1.0     1.0
"""
df = pd.read_csv(io.StringIO(data), delim_whitespace=True)

# Create series of indexes containing positions for raster plot
positions = df.apply(lambda x: df.index[x == 1])

# Create raster plot with inverted y-axis to display columns in ascending order
plt.eventplot(positions, lineoffsets=df.index, linelengths=0.75, colors='black')
plt.yticks(range(positions.index.size), positions.index)
plt.gca().invert_yaxis()

Answered By - Patrick FitzGerald