使用python3 numpy从txt文件加载浮动数字

Question

I am currently attempting to create a simple list of random floating numbers, save it in a text file and then loading the list of floating numbers with numpy using numpy.loadtxt .

For some reason whenever using loadtxt it states that the file is empty.

/usr/local/lib/python3.4/dist-packages/numpy/lib/npyio.py:891: UserWarning: loadtxt: Empty input file: "mydata1.txt"
warnings.warn('loadtxt: Empty input file: "%s"' % fname)

[ ]

class 'numpy.ndarray'

Here is a sample of the code:

import numpy
import scipy
import matplotlib
from random import random
import codecs

floats = list(random() for i in range (10))
fp = open('mydata1.txt','w')
for item in floats:
    str_item="{0:.5f}".format(item)
    fp.write("%s\n" % str_item )
fp.close

floats2 = numpy.loadtxt("mydata1.txt",dtype="str", delimiter="\n")
for myfloat in floats2:
    print("my floats is:",myfloat)
print(floats2)
print(type(floats2))

Answer 1

Change:

fp = open('mydata1.txt','w')
for item in floats:
    str_item="{0:.5f}".format(item)
    fp.write("%s\n" % str_item )
fp.close

into:

with open('mydata1.txt','w') as fp:
    for item in floats:
        fp.write("{0:.5f}\n".format(item))

and it should work.

The with open() opens the file and closes it as soon as you dedent your code. Your fp.close does not close the file because your are missing the parenthesis. It should be: fp.close() . Per default, files are opened in buffered mode. So, if you don't flush or close the file no or not all data gets written to your file.