Hello All, i need to extract data from an array, that are inside a rectangle area defined as :
N, S, E, W = 234560.94503118, 234482.56929822, 921336.53116178, 921185.3779625 the data are in a csv (comma delimited text file, with 3 columns X,Y,Z) #X,Y,Z 3020081.5500,769999.3100,0.0300 3020086.2000,769991.6500,0.4600 3020099.6600,769996.2700,0.9000 ... ... i read it using " numpy.loadtxt " data : http://www.geofemengineering.it/data/csv.txt 5,3 mb (158735 rows) to extract data that are inside the boundy-box area (N, S, E, W) i'm using a loop inside a function like : import numpy as np def getMinMaxBB(data, N, S, E, W): mydata = data * 0.3048006096012 for i in range(len(mydata)): if mydata[i,0] < E or mydata[i,0] > W or mydata[i,1] < N or mydata[i,1] > S : if i == 0: newdata = np.array((mydata[i,0],mydata[i,1],mydata[i,2]), float) else : newdata = np.vstack((newdata,(mydata[i,0], mydata[i,1], mydata[i,2]))) results = {} results['Max_Z'] = newdata.max(0)[2] results['Min_Z'] = newdata.min(0)[2] results['Num_P'] = len(newdata) return results N, S, E, W = 234560.94503118, 234482.56929822, 921336.53116178, 921185.3779625 data = '/Users/sasha/csv.txt' mydata = np.loadtxt(data, comments='#', delimiter=',') out = getMinMaxBB(mydata, N, S, E, W) print out This method works, but maybe is not soo fast, have you any hints on how to improve code with better performance ? thanks!!! Massimo. _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
