告诉 Python 等待/暂停“for”循环

Question

I have a Python program that navigates me to a website with a function that I have defined as nav(a, b), and on this site I will be downloading some pyfits data for use on another script. This site has a different pyfits file for every set of (a,b) in a catalog I have.

I was wondering if I could iterate through this catalog using a for loop, and each time the nav(a, b) function is used, tell python to pause while I download the file, then resume again when I tell it to. I've done something like this in IDL before, but don't know how with Python.

Otherwise I guess I'm stuck running the program 200 times, replacing the (a, b) values each time, which will take for ever.

Answer 1

If you want to wait for a manual signal to continue, wait for the user to press Enter :

Python 2:

raw_input("Press Enter to continue...")

Python 3:

input("Press Enter to continue...")

If you can download the file in the python code, do that instead of doing the manual task for each of the files.

Answer 2

You can use time.sleep() to pause the execution for t seconds:

import time
time.sleep(1.3) # Seconds

Demo:

import time

print "Start Time: %s" % time.ctime()
time.sleep(5)
print "End Time: %s" % time.ctime()

Output

Start Time: Tue Feb 17 10:19:18 2009
End Time: Tue Feb 17 10:19:23 2009

Answer 3

Use a while loop, waiting for your download to finish:

for ... :
    nav(a,b)
    while downloading_not_finished:
         time.sleep(X)

So, every X period of time a condition is tested, and is tested again until the downloading part is finished.

Answer 4

Okay, here are two ways to pause in Python.

1. You can use the input function.

    # Python 2 raw_input("Downloading....") # Python 3 input("Downloading....")

This will pause the program until the user presses Enter , etc.

2. You can use the time.sleep() function.

    import time time.sleep(number of seconds)

This will pause the Python script for however many seconds you want.

Answer 5

For Python shell in design:

import sys
from time import sleep

try:
    shell = sys.stdout.shell
except:
    print('Run It In Shell')
dots = '........';
shell.write('Downloading')
sleep(0.5)
for dot in dots:
    shell.write(dot)
    sleep(0.1)
shell.write('\n')
sleep(0.4)
shell.write('Saving Files')
sleep(0.5)
for doot in dots:
    shell.write(dot)
    sleep(0.1)
shell.write('\n')
sleep(0.4)

For Python in a console:

from time import sleep

print('Downloading')
sleep(1)
print('Saving Files')
sleep(1)

Answer 6

Use the input function. It will pause the program until the prompt has been closed/filled in.

Answer 7

The best solution is to put another while loop inside the existing while loop:

while True:
#do something
asleep = True
while (asleep):
    if cv2.waitKey(1) == 32: #Wait for space key  
        asleep = False