x-axis inverted unexpectedly by pandas.plot(…)

Question

X axis was inverted automatically and unexpectedly when plotting a series of data against another series of data using pandas. Please look at my code below. How can I ensure

Answer 1

You can enforce a direction for each plot:

(t,b)= ax.get_xlim()  ## Added for clarity
if t > b:
    ax.set_xlim((b,t))

or

if ax.xaxis_inverted():
    ax.invert_xaxis()

(the latter just do the explicit three-line version, though.)

Answer 2

I asked this question on the issue tracker of pandas, and got answer.

daraframe.plot(..) is designed such that

• x coordinate of points is determined based on the index (i.e. row number) of the column specified by x parameter.
• y coordinate of points is the value of the column specified by y parameter.

For a scatter plot, I think the above design is not suitable. The only solution I can think of is to use plt.plot direclty.

cphlewis's workaround is also useful.

Answer 3

To invert the graph you can use

arr1 = [1,2,3,4,5]
arr2 = [9,8,4,3,8]
df = pd.Dataframe(arr1,arr2)
df.plot.barh()

if you also want to print the graph in sorting then you can use

df.sort_values().plot.barh()

To enlarge the size of graph you can use

df.sort_values().plot.barh(figsize=(10,20))