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sorting list of lists - pframe - Apr-16-2020
I have the following:
list_1=[[499, 943, 1447, 943], [356, 944, 1447, 944], [356, 1226, 1447, 1226], [357, 1228, 1446, 1228], [292, 1456, 1441, 1456], [293, 1457, 1440, 1457], [292, 1991, 1441, 1991], [292, 2096, 1440, 2096], [293, 2098, 1440, 2098]]The list is set out in [[x1,y1,x2,y2],......] format and it is based in ascending order based off y1 (it is mean't to go down the page). Every coordinate is mean't to represent a line when joined.
list_1 has 5 lines in total, where as the above list tells me there are 9. Not only that, 3 lines are individual lines and far apart where as 2 lines are near each other together.
So for example:
[499, 943, 1447, 943] & [356, 944, 1447, 944] = 1 line (approx coordinate could be = [356, 944, 1447, 944] ) [356, 1226, 1447, 1226]& [357, 1228, 1446, 1228]=1 line (approx coordinate could be =[356, 1226, 1447, 1226]) [292, 1456, 1441, 1456]& [293, 1457, 1440, 1457] =1 line (approx coordinate could be = [292, 1456, 1441, 1456]) [292, 1991, 1441, 1991] & **[292, 2096, 1440, 2096], [293, 2098, 1440, 2098]** = 2 lines (where the bold coordinates represent the same line) (approx coordinate could be = [292, 1991, 1441, 1991] and [292, 2096, 1440, 2096])How do I write a function that automatically filters those coordinates and returns the right amount of lines i.e 5 and gives an approximation of where that line is.
RE: sorting list of lists - Larz60+ - Apr-16-2020
what have you tried?
show code working or not
RE: sorting list of lists - pframe - Apr-16-2020
from operator import itemgetter
import itertools
list_1=[[499, 943, 1447, 943], [356, 944, 1447, 944],
[356, 1226, 1447, 1226], [357, 1228, 1446, 1228],
[292, 1456, 1441, 1456], [293, 1457, 1440, 1457],
[292, 1991, 1441, 1991],
[292, 2096, 1440, 2096], [293, 2098, 1440, 2098]]
x1_value=list(map(itemgetter(0), a)) #sort out the x1 values
lowest_x=min(x1_value) #finds the lowest x1 value
#now i will replace all x1 value with the lowest so it is consistent x1
i=0
for i in range(0,len(a)):
a[i][0]=lowest_x
i+=1
# [[292, 943, 1447, 943], [292, 944, 1447, 944],
#[292, 1226, 1447, 1226], [292, 1228, 1446, 1228],
#[292, 1456, 1441, 1456], [292, 1457, 1440, 1457],
#[292, 1991, 1441, 1991], [292, 2096, 1440, 2096],
#[292, 2098, 1440, 2098]]
y1=list( map(itemgetter(1), a )) #puts y1 in a list
# narrow downs your y1 value
index = 1
while index < len(y1):
#print(f"comparing {y1[index-1]} with {y1[index]} y1 list {y1}")
if abs(y1[index] - y1[index - 1]) < 4:
del y1[index]
else:
index += 1
#print(a)
#print(y1)
#now i will check if my y1 list is in a. Where rr represent a and pp represent y
rr = a
pp = [[y] ]
result = []
ignore = []
for item in itertools.chain.from_iterable(pp):
for pair in rr:
if item in pair:
#print('Yepp, {} is in {}. Ignoring!'.format(item, pair))
ignore.append(pair)
elif not pair in result and pair not in ignore:
result.append(pair)
print(a)
print('Result: {}'.format(ignore))
# [[292, 943, 1447, 943], [292, 1226, 1447, 1226], [292, 1456, 1441, 1456], [292, 1991, 1441, 1991], [292, 2096, 1440, 2096]]As you can see it does the job, but is there a simple solution or a cleaner code that runs faster?
RE: sorting list of lists - Larz60+ - Apr-17-2020
how about:
list_1 = [
[499, 943, 1447, 943],
[356, 944, 1447, 944],
[356, 1226, 1447, 1226],
[357, 1228, 1446, 1228],
[292, 1456, 1441, 1456],
[293, 1457, 1440, 1457],
[292, 1991, 1441, 1991],
[292, 2096, 1440, 2096],
[293, 2098, 1440, 2098],
]
list_2 = sorted(list_1, key=lambda sublist: sublist[0])
print(f"list_2 = [")
for alist in list_2:
print(f" {alist}")
print(f"]")Gives:Output:list_2 = [
[292, 1456, 1441, 1456]
[292, 1991, 1441, 1991]
[292, 2096, 1440, 2096]
[293, 1457, 1440, 1457]
[293, 2098, 1440, 2098]
[356, 944, 1447, 944]
[356, 1226, 1447, 1226]
[357, 1228, 1446, 1228]
[499, 943, 1447, 943]
]RE: sorting list of lists - pframe - Apr-17-2020
The result is something like this.
# [[292, 943, 1447, 943], [292, 1226, 1447, 1226], [292, 1456, 1441, 1456], [292, 1991, 1441, 1991], [292, 2096, 1440, 2096]]list_1 represents a set of points [x1,y1,x2,y2] which form a line. So if you draw it out you can see what I am talking about. My solution above, basically eliminates those pseudo points/lines and returns one from each subset.
How I know it is there are 5 lines and in your solution it has more than 5 lines.
RE: sorting list of lists - Larz60+ - Apr-17-2020
There are 9 sub lists in your list_1 data.