How to create a subset list based upon another list values with Python

Question

I have three identical length lists for scatter plotting: x (float), y (float) and c (integer for colour), and would like to split up the x and y lists into subsets filtered by the colour value so that I can use a legend the delineate them in a plot

While I could achieve this with len(c) loops over the x and y lists, it is not very pythonic, and I was hoping someone could provide something a bit more elegant

I was thinking something like the following, but it's clearly not working

    c_list = list(set(c))
    xset = []
    yset = []
    for j in c_list:
        xset.append([i for i in x if j in c])
        yset.append([i for i in y if j in c])

Be gentle - I've only been learning Python for a week or so!

Thanks in advance

Chien Nguyen · Accepted Answer · 2019-01-25 02:28:23Z

1

I hope this helps:

x = [1, 2, 3, 4, 5]
y = [5, 3, 1, 3, 2]
c = [1, 3, 2, 3, 1]

c_list = list(set(c))
xset = []
yset = []
for j in c_list:
    xset.append([x[i] for i, v in enumerate(c) if v == j])
    yset.append([y[i] for i, v in enumerate(c) if v == j])

print(xset)
print(yset)

answered Jan 25, 2019 at 2:28

Chien Nguyen

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