检查python中的每一行是否存在条件并赋值给新变量
[英]Check if there is a condition in each row in python and assing to a new variable
问题描述
I have a dataframe unir in Python and I want to check if there is a certain text pattern in an URL. 
我在Python中有一个数据unir ，我想检查URL中是否有某种文本模式。 If the pattern is present, I want to assign a value to a new variable, if it doesn't, I want to leave the variable blank. 如果存在模式，则我想为新变量分配一个值，如果不存在，我想将该变量保留为空白。
A sample of my data is the following: 我的数据示例如下：
sample =[
"https://www.unir.net/revista/especiales/ley-de-factura-electronica.html",
"https://www.unir.net/revista/especiales/autoempleo/",
"https://www.unir.net/revista/",
"https://www.unir.net/revista/especiales/examen-acceso-abogacia.html",
"https://www.unir.net/revista/especiales/informe-pisa/",
"https://www.unir.net/revista/",
"https://www.unir.net/revista/especiales/dificultades-de-aprendizaje.html",
"https://www.unir.net/revista/especiales/informe-pisa/profesores-salarios.html",
"https://www.unir.net/revista/especiales/autoempleo/",
"https://www.unir.net/revista/evento/ii-festival-de-teatro-unir/",
"https://en.unir.net/revista/noticias/page/64/",
"https://www.unir.net/revista/especiales/autoempleo/",
"https://www.unir.net/revista/especiales/informe-pisa/profesores-salarios.html",
"https://www.unir.net/revista/"]
unir = pd.DataFrame(sample, columns=["url"])
And I'm searchig for the pattern " https://www.unir.net/revista/especiales " doing the following: 而且我正在搜索模式“ https://www.unir.net/revista/especiales ”，以执行以下操作：
for x in unir["url"]:
if (unir["url"].str.contains("https://www.unir.net/revista/especiales")) is True:
unir["arees"] = "Especiales"
else:
unir["arees"] = ""
But it only returns blanks. 但是它只返回空白。
I don't know what seems to be the problem... 我不知道这是什么问题...
Thanks in advance, 提前致谢，
1 个解决方案
解决方案1
1 已采纳 2018-10-04 14:38:16
In pandas is best avoid loops, because slow, better is use vectorized solution with numpy.where : 在熊猫中最好避免循环，因为比较慢，最好使用numpy.where矢量化解决方案：
mask = unir["url"].str.contains("https://www.unir.net/revista/especiales")
unir["arees"] = np.where(mask, "Especiales", '')
print (unir)
url arees
0 https://www.unir.net/revista/especiales/ley-de... Especiales
1 https://www.unir.net/revista/especiales/autoem... Especiales
2 https://www.unir.net/revista/
3 https://www.unir.net/revista/especiales/examen... Especiales
4 https://www.unir.net/revista/especiales/inform... Especiales
5 https://www.unir.net/revista/
6 https://www.unir.net/revista/especiales/dificu... Especiales
7 https://www.unir.net/revista/especiales/inform... Especiales
8 https://www.unir.net/revista/especiales/autoem... Especiales
9 https://www.unir.net/revista/evento/ii-festiva...
10 https://en.unir.net/revista/noticias/page/64/
11 https://www.unir.net/revista/especiales/autoem... Especiales
12 https://www.unir.net/revista/especiales/inform... Especiales
13 https://www.unir.net/revista/
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