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“git rm --cached x” vs “git reset head -- x”?
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There are three places where a file, say, can be - the tree, the index and the working copy. When you just add a file to a folder, you are adding it to the working copy.
When you do something like git add file you add it to the index. And when you commit it, you add it to the tree as well...
Find MongoDB records where array field is not empty
...ind({ pictures: { $exists: true, $not: {$size: 0} } })
MongoDB don't use indexes if $size is involved, so here is a better solution:
ME.find({ pictures: { $exists: true, $ne: [] } })
Since MongoDB 2.6 release, you can compare with the operator $gt but could lead to unexpected results (you can f...
How to check whether a pandas DataFrame is empty?
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I use the len function. It's much faster than empty. len(df.index) is even faster.
import pandas as pd
import numpy as np
df = pd.DataFrame(np.random.randn(10000, 4), columns=list('ABCD'))
def empty(df):
return df.empty
def lenz(df):
return len(df) == 0
def lenzi(df):
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How to remove item from list in C#?
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List<T> has two methods you can use.
RemoveAt(int index) can be used if you know the index of the item. For example:
resultlist.RemoveAt(1);
Or you can use Remove(T item):
var itemToRemove = resultlist.Single(r => r.Id == 2);
resultList.Remove(itemToRemove);
When yo...
How can I index a MATLAB array returned by a function without first assigning it to a local variable
...ssible to do what you want, but you have to use the functional form of the indexing operator. When you perform an indexing operation using (), you are actually making a call to the subsref function. So, even though you can't do this:
value = magic(5)(3, 3);
You can do this:
value = subsref(magic...
How can I remove a character from a string using Javascript?
... one instance of r in the string.
However, it is always the character at index 4 (so the 5th character).
18 Answers
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Append column to pandas dataframe
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@BenDundee I see. That method discards the unique index and has even weirder side effects in more complicated cases, though. For instance if I had two columns named 'data', grouping/summing would start summing up the different data columns, which is almost certainly not what...
php出现 Notice: Undefined index: xxx 的解决方法 - 更多技术 - 清泛网 - 专注IT技能提升
php出现 Notice: Undefined index: xxx 的解决方法Php_Notice_Undefined_index方法出现 "Undefined index: xxx "警告的原因：PHP 本身不需要事先声明变量即可直接使用，但是对未声明变量会有提示，最好的办法是使用变量之前先检查变量是否存在。...
ssl证书申请报错：challenge = [c for c in authorization[\'challenges\']...
...ge = [c for c in authorization['challenges'] if c['type'] == "http-01"][0] IndexError: list index out of rangechallenge-list-index-out-of-range使用acme-tiny申请ssl证书时报错：challenge = [c for c in authorization[& 39;challenges& 39;] if c[& 39;type& 39;] == "http-01"][0] IndexError: list ...
php出现 Notice: Undefined index: xxx 的解决方法 - 更多技术 - 清泛网 - 专注IT技能提升
php出现 Notice: Undefined index: xxx 的解决方法Php_Notice_Undefined_index方法出现 "Undefined index: xxx "警告的原因：PHP 本身不需要事先声明变量即可直接使用，但是对未声明变量会有提示，最好的办法是使用变量之前先检查变量是否存在。...