Downloading a file at a specified location through python and selenium using Chrome driver

I am trying to automatically download some links through selenium’s click functionality and I am using a chrome webdriver and python as the programming language. How can I select the download directory through the python program so that it does not get downloaded in the default Downloads directory. I found a solution for firefox but there the download dialog keeps popping up every time it clicks on the link which does not happen in Chrome.

python save image from url

I got a problem when I am using python to save an image from url either by urllib2 request or urllib.urlretrieve. That is the url of the image is valid. I could download it manually using the explorer. However, when I use python to download the image, the file cannot be opened. I use Mac OS preview to view the image. Thank you!