I'm working on microcontrollers, where it doesn't supports numpy or scipy. I want to extract all submatrices greater than given threshold value in matrix.
myMtarix = [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 204, 0, 0, 0, 0, 0, 0, 60, 0, 0, 284, 0],
[0, 100, 0, 74, 421, 157, 0, 0, 0, 0, 317, 364, 736, 245, 1470, 0],
[0, 717, 0, 258, 879, 496, 0, 0, 0, 0, 0, 671, 766, 725, 1429, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
myMatrix = 6*16 matrix and i want to extract
subMatrix1 = [[100],
[717]]
subMatrix2 = [[0, 204, 0],
[74, 421, 157],
[258, 879, 496]]
subMatrix3 = [[0, 60, 0, 0, 284],
[317, 364, 736, 245, 1470],
[0,671, 766, 725, 1429]]
and threshold = 10
I tried something like this
Here, collecting the values > threshold and their indexes
threshold = 10
pressureIndexes = []
pressurePoints = []
reqValue = []
reqIndex = []
reqValue = [myMatrix[i][j] for i in range(numRows) for j in range(numCols) if(myMatrix[i][j] > threshold)]
reqIndex = [[i,j] for i in range(numRows) for j in range(numCols) if(myMatrix[i][j] > threshold)]
from here, I'm try to extract the the exact boundaries of submatrices
Xend = Xstart = reqIndex[0][0]
Yend = Ystart = reqIndex[0][1]
dummy = []
for i in range(1,len(reqIndex)):
PXstart = Xstart
PXend = Xend
PYstart = Ystart
PYend = Yend
Xstart = min(Xstart,reqIndex[i][0])
Xend = max(Xend,reqIndex[i][0])
Ystart = min(PYstart,reqIndex[i][1])
Yend = max(PYend,reqIndex[i][1])
if(abs(PXend-Xend) > 2 or abs(PYend-Yend) > 2):
dummy.append([[PXstart,PXend],[PYstart,PYend]])
Xend = Xstart = reqIndex[i][0]
Yend = Ystart = reqIndex[i][1]
dummy.append([[Xstart,Xend],[Ystart,Yend]])
print()
for i in dummy:
print(i)
print('---------------------------------------------------------')
sleep(1)
OUTPUT :
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[0, 0, 0, 0, 204, 0, 0, 0, 0, 0, 0, 60, 0, 0, 284, 0]
[0, 100, 0, 74, 421, 157, 0, 0, 0, 0, 317, 364, 736, 245, 1470, 0]
[0, 717, 0, 258, 879, 496, 0, 0, 0, 0, 0, 671, 766, 725, 1429, 0]
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[[1, 1], [4, 4]] # [[rowStarting,rowEnding],[colStarting,colEnding]] for value 204
[[1, 1], [11, 11]]
[[1, 3], [1, 14]]
Here is a way to do it, it will returns a list of sub-matrices with no 0 line or column:
mm = [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 204, 0, 0, 0, 0, 0, 0, 60, 0, 0, 284, 0],
[0, 100, 0, 74, 421, 157, 0, 0, 0, 0, 317, 364, 736, 245, 1470, 0],
[0, 717, 0, 258, 879, 496, 0, 0, 0, 0, 0, 671, 766, 725, 1429, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
## values below threshold are set to 0
def threshold(m, th=10):
for l in range(len(m)):
for c in range(len(m[l])):
v=m[l][c]
if v < th:
v = 0
m[l][c] = v
return m
## helper functions to handle matrixes
## work with a colum values
def column(m, c):
return list(map(lambda x: x[c], m))
## cut and drop left of matrix
def cutleftofcolumn(m, c):
return list(map(lambda x: x[c+1:], m))
## cut and drop right of matrix
def cutrightofcolumn(m, c):
return list(map(lambda x: x[:c], m))
## remove 0 borders of the matrix
def removeBorders(m: list) -> list:
test = True
while test:
test = False
#if sum(m[0])==0:
if all(map(lambda x: x==0, m[0])):
m = m[1:]
test = True
#if sum(m[-1])==0:
if all(map(lambda x: x==0, m[-1])):
m = m[:-1]
test = True
#if sum(column(m, 0))==0:
if all(map(lambda x: x==0, column(m, 0))):
m=cutleftofcolumn(m, 0)
test = True
#if sum(column(m, -1))==0:
if all(map(lambda x: x==0, column(m, -1))):
m=cutrightofcolumn(m, -1)
test = True
return m
## split on a 0 column and returns 2 matrices
def splitv(m, c):
a=cutleftofcolumn(m, c)
b=cutrightofcolumn(m, c)
return [a, b]
## split on a 0 line and returns 2 matrices
def splith(m, l):
return [m[0:l], m[l+1:]]
mm = threshold(mm, 10)
listMatrices = [mm]
test = True
while (test):
test=False
index = 0
while (len (listMatrices)>index):
## get first matrix of the list
m = listMatrices.pop(0)
## removes 0 borders of the matrix
m = removeBorders(m)
lll=[]
## try to find an horizontal split on 0 line
if lll==[]:
for l in range(len(m)):
#if sum(m[l])==0:
if all(map(lambda x: x==0, m[l])):
lll = lll + splith(m, l)
test = True
break
## try to find a vertical split on 0 column
if lll==[]:
for c in range(len(m[0])):
cc = column(m, c)
#if sum(cc)==0:
if all(map(lambda x: x==0, cc)):
lll = lll + splitv(m, c)
#print("Csum=0", c)
test = True
break
if lll==[]:
listMatrices.append(m)
else:
for l in lll:
listMatrices.append(l)
index+=1
print(listMatrices)
Output is:
[[[0, 60, 0, 0, 284], [317, 364, 736, 245, 1470], [0, 671, 766, 725, 1429]],
[[0, 204, 0], [74, 421, 157], [258, 879, 496]],
[[100], [717]]]