Tuple pairs, finding minimum using python
Using numpy, you can use these commands to get the tuple in list where item is minimum:
The ingredients that make this work are numpy's advanced array slicing and argsort features.
import numpy as np#create a python list of tuples and convert it to a numpy ndarray of floatsdata = np.array([ (1, 7.57), (2, 2.1), (3, 1.2), (4, 2.1), (5, 0.01), (6, 0.5), (7, 0.2), (8, 0.6)])print("data is")print(data)#Generate sortIndices from second columnsortIndices = np.argsort(data[:,1])print("sortIndices using index 1 is:" )print(sortIndices)print("The column at index 1 is:")print(data[:,1])print("Index 1 put into order using column 1")print(data[sortIndices,1])print("The tuples put into order using column 1")print(data[sortIndices,:])print("The tuple with minimum value at index 1")print(data[sortIndices[0],:])print("The tuple with maximum value at index 1")print(data[sortIndices[-1],:])Which prints:
data is[[ 1. 7.57] [ 2. 2.1 ] [ 3. 1.2 ] [ 4. 2.1 ] [ 5. 0.01] [ 6. 0.5 ] [ 7. 0.2 ] [ 8. 0.6 ]]sortIndices using index 1 is:[4 6 5 7 2 1 3 0]The column at index 1 is:[ 7.57 2.1 1.2 2.1 0.01 0.5 0.2 0.6 ]Index 1 put into order using column 1[ 0.01 0.2 0.5 0.6 1.2 2.1 2.1 7.57]The tuples put into order using column 1[[ 5. 0.01] [ 7. 0.2 ] [ 6. 0.5 ] [ 8. 0.6 ] [ 3. 1.2 ] [ 2. 2.1 ] [ 4. 2.1 ] [ 1. 7.57]]The tuple with minimum value at index 1[ 5. 0.01]The tuple with maximum value at index 1[ 1. 7.57]
Even though Lev's answer is correct, I wanted to add the sort Method as well, in case someone is interested in the first n minimas. One thing to consider is that the min operation's runtime is O(N) where the sort's is O(N Log N)
data = [ (1, 7.57), (2, 2.1), (3, 1.2), (4, 2.1), (5, 0.01), (6, 0.5), (7, 0.2), (8, 0.6)]data.sort(key=lambda x:x[1])print data>>> [(5, 0.01), (7, 0.2), (6, 0.5), (8, 0.6), (3, 1.2), (2, 2.1), (4, 2.1), (1, 7.57)]https://www.ics.uci.edu/~pattis/ICS-33/lectures/complexitypython.txt