# Matplotlib - Step Plot

A step plot displays vertical lines that connect the data points to a horizontal baseline. A step plot enables to see the point on the x-axis when a change in the y-axis measure occurs.

The matplotlib.pyplot.step() function makes a step plot.

### Syntax

```matplotlib.pyplot.stepplot(x, y, [fmt], where='pre')
```

### Parameters

 `x` `Required. `Specify 1D sequence of x positions. It is assumed, but not checked, that it is uniformly increasing. array-like. `y` `Required. `Specify 1D sequence of y levels.array-like. `[fmt]` `Optional. `Specify a format string, e.g. 'g' for a green line. `where` `Optional. `It takes value from {'pre', 'post', 'mid'}. Default is 'pre'. This defines where the steps should be placed: 'pre': The y value is continued constantly to the left from every x position, i.e. the interval (x[i-1], x[i]] has the value y[i]. 'post': The y value is continued constantly to the right from every x position, i.e. the interval [x[i], x[i+1]) has the value y[i]. 'mid': Steps occur half-way between the x positions.

### Example: step plot

In the example below, a step plot of three different curves are drawn. Along with this, three line plots are also drawn to illustrate the effect of where parameter of the step plot.

```import matplotlib.pyplot as plt
import numpy as np

x = np.arange(14)
y = np.sin(x / 2)

fig, ax = plt.subplots()
ax.set_title('plt.step(where=...)')

#drawing step plot
ax.step(x, y+2)
ax.step(x, y+1, where='mid')
ax.step(x, y, where='post')

#indicating where
ax.plot(x, y + 2, 'o--', color='grey', alpha=0.3)
ax.plot(x, y + 1, 'o--', color='grey', alpha=0.3)
ax.plot(x, y, 'o--', color='grey', alpha=0.3)

labels = ['pre (default)', 'mid', 'post']
ax.legend(title='Parameter where:', labels=labels)

plt.show()
```

The output of the above code will be:

### Example: step plot using pyplot.plot

The same can also be achieved without using step() function. For this, we have to use drawstyle parameter of pyplot.plot.

```import matplotlib.pyplot as plt
import numpy as np

x = np.arange(14)
y = np.sin(x / 2)

fig, ax = plt.subplots()
ax.set_title('plt.plot(drawstyle=...)')

#drawing plots with different drawstyle
ax.plot(x, y+2, drawstyle='steps')
ax.plot(x, y+1, drawstyle='steps-mid')
ax.plot(x, y, drawstyle='steps-post')

#indicating drawstyle
ax.plot(x, y + 2, 'o--', color='grey', alpha=0.3)
ax.plot(x, y + 1, 'o--', color='grey', alpha=0.3)
ax.plot(x, y, 'o--', color='grey', alpha=0.3)

labels = ['steps (=steps-pre)', 'steps-mid', 'steps-post']
ax.legend(title='Parameter drawstyle:', labels=labels)

plt.show()
```

The output of the above code will be:

5