entityMap|blocks|key|6olja|text|将for循环更改为：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|fr9i3|for+a+in+range(0,len(pixels)):
++++if+pixels[a]<100:
++++++++dark.append(pixels[a])
++++++++dposition.append(a)|code-block|syntax|javascript|uegh|本质上，这允许我们访问像素红色通道数据和列表中该像素的索引，因此每次我们将某些内容添加到暗像素列表中时，我们都会将其索引添加到dposition列表中。|2etk9^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|K|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|L|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|M|9|@]|A|@]|B|$]]|$2|J|4|-4|6|7|8|N|9|@]|A|@]|B|$]]]]

Change your for loop to this:

<pre><code>for a in range(0,len(pixels)):
 if pixels[a]&lt;100:
 dark.append(pixels[a])
 dposition.append(a)
</code></pre>

Essentially what this does is allow us to access both the pixel red channel data AND the index of that pixel in the list, so that every time we append something to the list of dark pixels, we append it’s index to the dposition list.

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://docs.python.org/2/library/functions.html#enumerate|blocks|key|1h0hk|text|您需要的是一种在遍历列表时确定索引位置的方法。在遍历列表时，您可以创建一个简单的计数器而不是增量：|unstyled|depth|inlineStyleRanges|entityRanges|3f5km|dark+=+[]
dposition+=+[]
count+=+0
for+a+in+pixels:
++++if+a<100:
++++++++dark.append(a)
++++++++dposition.append(count)
++++count+%2B=+1|code-block|syntax|javascript|eo84n|或者，您可以使用Python内置的enumerate函数在遍历位置时生成位置：|offset|length|style|CODE|6524m|dark+=+[]
dposition+=+[]
for+position,+a+in+enumerate(pixels):
++++if+a<100:
++++++++dark.append(a)
++++++++dposition.append(position)|36rsk^0|0|0|H|9|H|9|0|0|0^^$0|$1|$2|3|4|5|6|$7|8]]]|9|@$A|B|C|D|2|E|F|W|G|@]|H|@]|6|$]]|$A|I|C|J|2|K|F|X|G|@]|H|@]|6|$L|M]]|$A|N|C|O|2|E|F|Y|G|@$P|Z|Q|10|R|S]]|H|@$P|11|Q|12|A|13]]|6|$]]|$A|T|C|U|2|K|F|14|G|@]|H|@]|6|$L|M]]|$A|V|C|-4|2|E|F|15|G|@]|H|@]|6|$]]]]

What you need is a way to determine the index position as you iterate through the list. You can create a simple counter than increments as you go through the list:

<pre><code>dark = []
dposition = []
count = 0
for a in pixels:
 if a&lt;100:
 dark.append(a)
 dposition.append(count)
 count += 1
</code></pre>

Or you can use Python's built in <a href="https://docs.python.org/2/library/functions.html#enumerate" rel="nofollow noreferrer"><code>enumerate</code></a> function to generate the position as you iterate through it:

<pre><code>dark = []
dposition = []
for position, a in enumerate(pixels):
 if a&lt;100:
 dark.append(a)
 dposition.append(position)
</code></pre>

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://docs.python.org/3/library/functions.html#enumerate|1|https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions|2|https://pillow.readthedocs.io/en/5.1.x/reference/Image.html#PIL.Image.Image.getdata|blocks|key|9vu3r|text|如果你只对暗像素的位置感兴趣，enumerate()+%2B+list+comprehension会给你一行提示：|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|can5u|dposition+=+[position+for+position,+red+in+enumerate(pixels)+if+red+<+100]|ckc55|顺便说一句，根据getdata()的文档，默认返回所有波段。您可能希望使用getdata(band=0)代替红色波段。|a4etv^0|F|B|F|B|0|T|I|1|0|0|22|0|8|9|11|F|8|9|2|0^^$0|$1|$2|3|4|5|6|$7|8]]|9|$2|3|4|5|6|$7|A]]|B|$2|3|4|5|6|$7|C]]]|D|@$E|F|G|H|2|I|J|V|K|@$L|W|M|X|N|O]]|P|@$L|Y|M|Z|E|10]|$L|11|M|12|E|13]]|6|$]]|$E|Q|G|R|2|I|J|14|K|@$L|15|M|16|N|O]]|P|@]|6|$]]|$E|S|G|T|2|I|J|17|K|@$L|18|M|19|N|O]|$L|1A|M|1B|N|O]]|P|@$L|1C|M|1D|E|1E]]|6|$]]|$E|U|G|-4|2|I|J|1F|K|@]|P|@]|6|$]]]]

If you are only interested in the positions of the dark pixels, <a href="https://docs.python.org/3/library/functions.html#enumerate" rel="nofollow noreferrer"><code>enumerate()</code></a> + <a href="https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions" rel="nofollow noreferrer">list comprehension</a> gives you a one-liner:

<code>dposition = [position for position, red in enumerate(pixels) if red &lt; 100]</code>

BTW, according to the doc of <a href="https://pillow.readthedocs.io/en/5.1.x/reference/Image.html#PIL.Image.Image.getdata" rel="nofollow noreferrer"><code>getdata()</code></a>, it returns all bands by default. You might want to use <code>getdata(band=0)</code> instead for red band.

entityMap|blocks|key|5u5pd|text|你创建了一个一维数组，所以大多数其他答案都会给出你在该一维数组中的位置。如果你需要x和y职位，下面是你可以做的：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1jpjs|import+PIL
from+PIL+import+Image
import+os
import+numpy+as+np

im=Image.open('cat.jpg')

im=im.getchannel(0)|code-block|syntax|javascript|4uul2|转换为二维numpy数组。|7fppc|im+=+np.asarray(im)
dposition+=+[]
for+i,+row+in+enumerate(im):
++++for+j,+pixel+in+enumerate(row):
++++++++if+pixel+<+100:
++++++++++++dposition.append((i,+j))

print(dposition)|tt7^0|15|1|17|1|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|Q|9|@$A|R|B|S|C|D]|$A|T|B|U|C|D]]|E|@]|F|$]]|$2|G|4|H|6|I|8|V|9|@]|E|@]|F|$J|K]]|$2|L|4|M|6|7|8|W|9|@]|E|@]|F|$]]|$2|N|4|O|6|I|8|X|9|@]|E|@]|F|$J|K]]|$2|P|4|-4|6|7|8|Y|9|@]|E|@]|F|$]]]]

You created a 1d array so most the other answers will give you the position in that 1d array. Here's what you can if you need the <code>x</code> and the <code>y</code> position: 

<pre><code>import PIL
from PIL import Image
import os
import numpy as np

im=Image.open('cat.jpg')

im=im.getchannel(0)
</code></pre>

Convert to a 2d numpy array.

<pre><code>im = np.asarray(im)
dposition = []
for i, row in enumerate(im):
 for j, pixel in enumerate(row):
 if pixel &lt; 100:
 dposition.append((i, j))

print(dposition)
</code></pre>

pretty new to python so this might be pretty simple.

I'm working with PIL and I have generated a list of pixel information using Image.getdata(). My goal is to find all dark pixels in the red channel of the image and create a list of where they occur in the overall list of pixels. Here is what I have.

<pre><code>import PIL
from PIL import Image
import os

os.chdir('Correct Path')

im=Image.open('TRY.jpg')
im=im.getchannel(0)
pixels = list(im.getdata())

dark = []
dposition = []
for a in pixels:
 if a&lt;100:
 dark.append(a)

print(dark)
</code></pre>

So my goal is to fill the list "dposition" with the locations of all of the dark pixels within the list "pixels", but I am totally stumped on how to do so! So far the list "dark" works in showing the value of all pixels with a red value of &lt;100. Any help is appreciated, thank you!

Trouble getting the position of an element while looping through a list (Python)

 这是python的新手，所以这可能非常简单。 我正在使用PIL，并且我已经使用Image.getdata()生成了一个像素信息列表。我的目标是找到图像红色通道中的所有暗像素，并创建它们在整个像素列表中出现的位置的列表。这就是我所拥有的。 import PILfrom PIL import Imageimport os...

问在遍历列表时获取元素位置时出现问题(Python)
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