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How to check whether a pandas DataFrame is empty?
...[8]: len(df1.columns)
Out[8]: 0
In [9]: len(df2.columns)
Out[9]: 2
Critically, while the second dataframe df2 contains no data, it is not completely empty because it returns the amount of empty columns that persist.
Why it matters
Let's add a new column to these dataframes to understand the implic...
How do you do a case insensitive search using a pattern modifier using less?
... like the only way to do this is to pass the -i parameter in when you initially run less. Does anyone know of some secret hack to make something like this work
...
Command to get nth line of STDOUT
...ssage:
ls -l | sed -n -e '2{p;q}'
I've seen that often enough that I usually use the first (which is easier to type, anyway), though ls is not a command that complains when it gets SIGPIPE.
For a range of lines:
ls -l | sed -n 2,4p
For several ranges of lines:
ls -l | sed -n -e 2,4p -e 20,30...
CORS: Cannot use wildcard in Access-Control-Allow-Origin when credentials flag is true
...
This is a part of security, you cannot do that. If you want to allow credentials then your Access-Control-Allow-Origin must not use *. You will have to specify the exact protocol + domain + port. For reference see these questions :
Access-Control-Allow-Origin wildcard subdomains, ports...
How to accept Date params in a GET request to Spring MVC Controller?
...can I suggest that you use the Joda DateTime library. Spring supports it really well.
– Luciano
Mar 1 '13 at 19:06
The...
Hg: How to do a rebase like git's rebase
...er mq nor rebase are enabled by default in mercurial: because mercurial is all about indelible changesets. When I work in the manner you're describing, which is nearly daily, here's the pattern I take:
1. Start working on a new feature:
$ hg clone mainline-repo newfeature-123
do a few commits (M, ...
How do I use shell variables in an awk script?
...o it becomes a part of it.
If you want to make an awk that changes dynamically with use of variables, you can do it this way, but DO NOT use it for normal variables.
variable="line one\nline two"
awk 'BEGIN {print "'"$variable"'"}'
line one
line two
Here is an example of code injection:
variabl...
How to display gpg key details without importing it?
...from the warning.
Technical Details: Listing OpenPGP Packets
Without installing any further packages, you can use gpg --list-packets [file] to view information on the OpenPGP packets contained in the file.
$ gpg --list-packets a4ff2279.asc
:public key packet:
version 4, algo 1, created 135647...
Embedding Python in an iPhone app
...
It doesn't really matter how you build Python -- you don't need to build it in Xcode, for example -- but what does matter is the product of that build.
Namely, you are going to need to build something like libPython.a that can be statica...
How to convert a String into an ArrayList?
...
Hehe, yeah, +1 :-) It may actually even just be the split his after :P
– aioobe
Sep 8 '11 at 13:47
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