How to transform a 2d array in to two different 1d array in python

Question

I’m trying to transform one 2d array:

{4: 6, 6: 2, 1: 2, 3: 7, 5: 4, 9: 1, 2: 3, 7: 2, 8: 1}

in to 2 different 1d arrays, like this:

arr1 = [1, 2, 3, 4, 5, 6, 7, 8, 9] 
arr2 = [2, 3, 7, 6, 4, 2, 2, 1, 1]

To plot, using matplotlib, arr1 as y and arr2 as x.

How can I do this?

PS: Sorry for the bad English. (;

Asked By: jazz_man07

||

Source

Answer 1

here is what you can do:

import matplotlib.pylab as plt
d = {4: 6, 6: 2, 1: 2, 3: 7, 5: 4, 9: 1, 2: 3, 7: 2, 8: 1}
sorted_list = sorted(d.items()) # sorted by key, return a list of tuples
x, y = zip(*sorted_list) # unpack a list of pairs into two tuples

plt.plot(x, y)
plt.show()

output :

Answered By: eshirvana

Answer 2

You can use dict.items and zip:

d = {4: 6, 6: 2, 1: 2, 3: 7, 5: 4, 9: 1, 2: 3, 7: 2, 8: 1}

arr1, arr2 = map(list, zip(*d.items()))

output:

arr1
# [1, 2, 3, 4, 5, 6, 7, 8, 9] 

arr2
# [2, 3, 7, 6, 4, 2, 2, 1, 1]

A convenience, if you want to plot, might be to use pandas.Series:

import pandas as pd

pd.Series(d).sort_index().plot()

# or
# import matplotlib .pyplot as plt
# plt.plot(pd.Series(d).sort_index())

output:

Answered By: mozway

How to transform a 2d array in to two different 1d array in python

Question:

Answers: