Plotting a python dict in order of key values

Question

I have a python dictionary that looks like this    In 1   dict concentration Out 2     0  0 19849878712984576  5000  0 093917341754771386  10000  0 075060643507712022  20000  0 06673074282575861  30000  0 057119318961966224  50000  0 046134834546203485  100000  0 032495766396631424  200000  0 018536317451599615  500000  0 0059499290585381479    They keys are type int  the values are type float64   Unfortunately  when I try to plot this with lines  matplotlib connects the wrong points  plot attached   How can I make it connect lines in order of the key values

User · Answer

Simply pass the sorted items from the dictionary to the plot() function. concentration.items() returns a list of tuples where each tuple contains a key from the dictionary and its corresponding value.

You can take advantage of list unpacking (with *) to pass the sorted data directly to zip, and then again to pass it into plot():

import matplotlib.pyplot as plt

concentration = {
    0: 0.19849878712984576,
    5000: 0.093917341754771386,
    10000: 0.075060643507712022,
    20000: 0.06673074282575861,
    30000: 0.057119318961966224,
    50000: 0.046134834546203485,
    100000: 0.032495766396631424,
    200000: 0.018536317451599615,
    500000: 0.0059499290585381479}

plt.plot(*zip(*sorted(concentration.items())))
plt.show()

sorted() sorts tuples in the order of the tuple's items so you don't need to specify a key function because the tuples returned by dict.item() already begin with the key value.

User · Answer

Python dictionaries are unordered  If you want an ordered dictionary  use collections OrderedDict  In your case  sort the dict by key before plotting   import matplotlib pylab as plt  lists   sorted d items      sorted by key  return a list of tuples  x  y   zip  lists    unpack a list of pairs into two tuples  plt plot x  y  plt show       Here is the result

[python] Plotting a python dict in order of key values

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