Sum elements in a row (Python/Numpy)
Solution 1
You're over-complicating it. Instead try:
np.sum(array,axis=1).tolist()
this should return a list which contain the sum of all rows
ex:
import numpy as np
array = np.array([range(10),range(10),range(10),range(10)])
sum_ = np.sum(array,axis=1).tolist()
print sum_
print type(sum_)
>> [45, 45, 45, 45]
>> <type 'list'>
Solution 2
Okay. Figured out the answer.
@wajid Farhani was close, but it wasn't working in my case.
His command for np.sum works, but I had to perform some indexing so I can ignore index 0 of every row. My issue was that I thought indexing 2D array was done by array[x][y], when it's array[x,y].
Fixed code:
import numpy
print ("Reading..")
txtfile = open("test1.txt", "r")
print(txtfile.readline())
txtfile.close()
r= numpy.genfromtxt('test1.txt',dtype=str,skiprows=1)
for x in range (0,len(r)):
print(r[x])
allTested = [0] * (len(r[0]) - 1)
num1s = [0] * (len(r))
print("number of rows:", len(r))
print("number of cols:", len(r[0]))
print("num1s before:",num1s)
array = numpy.array(r,dtype=int)
s = numpy.sum(array[0:len(array),1:len(array[0])],axis=1).tolist()
print("num1s after :",s)
Correct output:
num1s before: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
num1s after : [1, 4, 4, 4, 4, 5, 5, 3, 4, 5, 5, 3, 4, 3, 3, 3]
Admin
Updated on April 28, 2021Comments
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Admin about 3 years
Working on a project that gives us free reign on what to use. So I decided I'd learn python for it.
To make this short, I want sum all the elements in a "row" of a matrix I'm reading in.
This is what my 2D array looks like after I read in my table from my text file.
['0000' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '1'] ['0001' '0' '1' '0' '1' '0' '0' '0' '0' '1' '0' '0' '0' '0' '1'] ['0010' '0' '1' '0' '1' '0' '0' '0' '0' '1' '0' '0' '0' '0' '1'] ['0011' '0' '1' '0' '1' '0' '0' '0' '0' '1' '0' '0' '0' '0' '1'] ['0100' '0' '0' '0' '0' '0' '1' '0' '1' '0' '0' '1' '0' '0' '1'] ['0101' '0' '0' '1' '0' '0' '0' '1' '0' '0' '1' '0' '1' '1' '0'] ['0110' '0' '0' '1' '0' '1' '0' '0' '0' '0' '1' '0' '1' '1' '0'] ['0111' '0' '0' '1' '0' '0' '0' '0' '0' '0' '1' '0' '0' '1' '0'] ['1000' '0' '0' '0' '0' '0' '1' '0' '1' '0' '0' '1' '0' '0' '1'] ['1001' '1' '0' '0' '0' '0' '0' '1' '0' '0' '1' '0' '1' '1' '0'] ['1010' '1' '0' '0' '0' '1' '0' '0' '0' '0' '1' '0' '1' '1' '0'] ['1011' '1' '0' '0' '0' '0' '0' '0' '0' '0' '1' '0' '0' '1' '0'] ['1100' '0' '0' '0' '0' '0' '1' '0' '1' '0' '0' '1' '0' '0' '1'] ['1101' '0' '0' '0' '0' '0' '0' '1' '0' '0' '0' '0' '1' '1' '0'] ['1110' '0' '0' '0' '0' '1' '0' '0' '0' '0' '0' '0' '1' '1' '0'] ['1111' '0' '0' '0' '0' '0' '0' '0' '0' '0' '1' '0' '1' '1' '0']
I want to sum all elements of each row excluding index 0 (the 4 digit numbers). And then store those sums in a list.
This is what my list of sums should look like:
[1, 4, 4, 4, 4, 4, 5, 5, 3,.......,3] (Imagine it was all filled with the right sums)
However, this is what my code outputs:
number of rows: 16 number of cols: 15 num1s before: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] num1s after : [3, 3, 3, 3, 3, 3, 3, 3, 3, 7, 3, 7, 9, 7]
I'm not sure what the error is, but I think it has to do with string/int conversion. Since my table is in strings, but I convert it to ints for summing. Debugging it shows the correct results, so I'm not sure where the error is.
Here is my code:
import numpy print ("Reading..") txtfile = open("test1.txt", "r") print(txtfile.readline()) txtfile.close() r= numpy.genfromtxt('test1.txt',dtype=str,skiprows=1) for x in range (0,len(r)): print(r[x]) allTested = [0] * (len(r[0]) - 1) num1s = [0] * (len(r[0]) - 1) print("number of rows:", len(r)) print("number of cols:", len(r[0])) print("num1s before:",num1s) for x in range (0,len(r)): for y in range(1,len(r[0])): num1s[y-1] += int(r[x][y]) print("num1s after :",num1s)