# Reverse Y-Axis in PyPlot

Each Answer to this Q is separated by one/two green lines.

I have a scatter plot graph with a bunch of random x, y coordinates. Currently the Y-Axis starts at 0 and goes up to the max value. I would like the Y-Axis to start at the max value and go up to 0.

``````points = [(10,5), (5,11), (24,13), (7,8)]
x_arr = []
y_arr = []
for x,y in points:
x_arr.append(x)
y_arr.append(y)
plt.scatter(x_arr,y_arr)
``````

There is a new API that makes this even simpler.

``````plt.gca().invert_xaxis()
``````

and/or

``````plt.gca().invert_yaxis()
``````

DisplacedAussie‘s answer is correct, but usually a shorter method is just to reverse the single axis in question:

``````plt.scatter(x_arr, y_arr)
ax = plt.gca()
ax.set_ylim(ax.get_ylim()[::-1])
``````

where the `gca()` function returns the current Axes instance and the `[::-1]` reverses the list.

You could also use function exposed by the axes object of the scatter plot

``````scatter = plt.scatter(x, y)
ax = scatter.axes
ax.invert_xaxis()
ax.invert_yaxis()
``````

`axis([xmin, xmax, ymin, ymax])`

So you could add something like this at the end:

``````plt.axis([min(x_arr), max(x_arr), max(y_arr), 0])
``````

Although you might want padding at each end so that the extreme points don’t sit on the border.

If you’re in ipython in `pylab` mode, then

``````plt.gca().invert_yaxis()
show()
``````

the `show()` is required to make it update the current figure.

Another similar method to those described above is to use `plt.ylim` for example:

``````plt.ylim(max(y_array), min(y_array))
``````

This method works for me when I’m attempting to compound multiple datasets on Y1 and/or Y2

using ylim() might be the best approach for your purpose:

``````xValues = list(range(10))
quads = [x** 2 for x in xValues]
``````

will result:

Alternatively, you can use the matplotlib.pyplot.axis() function, which allows you inverting any of the plot axis

``````ax = matplotlib.pyplot.axis()
matplotlib.pyplot.axis((ax[0],ax[1],ax[3],ax[2]))
``````

Or if you prefer to only reverse the X-axis, then

``````matplotlib.pyplot.axis((ax[1],ax[0],ax[2],ax[3]))
``````

Indeed, you can invert both axis:

``````matplotlib.pyplot.axis((ax[1],ax[0],ax[3],ax[2]))
``````

If using matplotlib you can try:
``` matplotlib.pyplot.xlim(l, r) matplotlib.pyplot.ylim(b, t) ```

These two lines set the limits of the x and y axes respectively. For the x axis, the first argument l sets the left most value, and the second argument r sets the right most value. For the y axis, the first argument b sets the bottom most value, and the second argument t sets the top most value.

If using matplotlib we can make plot in reverse y axis in these 3 different ways:
1.By Specifying ymaximum value as y_min and yminimum as y_max

``````plt.xlim(x_min,x_max)
plt.ylim(y_min,y_max)
plt.xlim(0, 80)
plt.ylim(100, 0)
``````
1. Specifying axis

plt.axis([x_min, x_max, y_min, y_max])
plt.axis([0, 80, 100, 0])

3.Using gca()function of matplotlib and calling invert_yaxis()function

``````ax = plt.gca()
ax.invert_yaxis()
``````

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