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Selecting pandas column by location
... to mind:
>>> df
A B C D
0 0.424634 1.716633 0.282734 2.086944
1 -1.325816 2.056277 2.583704 -0.776403
2 1.457809 -0.407279 -1.560583 -1.316246
3 -0.757134 -1.321025 1.325853 -2.513373
4 1.366180 -1.265185 -2.184617 0.881514
>>> df.iloc[...
pandas: filter rows of DataFrame with operator chaining
...olean index.
In [96]: df
Out[96]:
A B C D
a 1 4 9 1
b 4 5 0 2
c 5 5 1 0
d 1 3 9 6
In [99]: df[(df.A == 1) & (df.D == 6)]
Out[99]:
A B C D
d 1 3 9 6
If you want to chain methods, you can add your own mask method and use that one.
In [90]: def mask(df, key, val...
How to find time complexity of an algorithm
...de any simplifying constant factor.
For example, lets see how we simplify 2N + 2 machine instructions to describe this as just O(N).
Why do we remove the two 2s ?
We are interested in the performance of the algorithm as N becomes large.
Consider the two terms 2N and 2.
What is the relative inf...
efficient circular buffer?
...
206
I would use collections.deque with a maxlen arg
>>> import collections
>>> ...
How to sort a list of lists by a specific index of the inner list?
...;>> from operator import itemgetter
>>> L=[[0, 1, 'f'], [4, 2, 't'], [9, 4, 'afsd']]
>>> sorted(L, key=itemgetter(2))
[[9, 4, 'afsd'], [0, 1, 'f'], [4, 2, 't']]
It is also possible to use a lambda function here, however the lambda function is slower in this simple case
...
Print all but the first three columns
...s",$i OFS; if(NF) printf "%s",$NF; printf ORS}'
### Example ###
$ echo '1 2 3 4 5 6 7' |
awk '{for(i=4;i<NF;i++)printf"%s",$i OFS;if(NF)printf"%s",$NF;printf ORS}' |
tr ' ' '-'
4-5-6-7
Sudo_O proposes an elegant improvement using the ternary operator NF?ORS:OFS
$ echo '1 2 3 4 5 6 7' |
...
java.net.ConnectException: localhost/127.0.0.1:8080 - Connection refused
...
292
Since you have not specified you are connected to a server from the device or emulator so I gu...
How to install GCC piece by piece with GMP, MPFR, MPC, ELF, without shared libraries?
...
124
The Easy Way
If you're a typical developer, you can install the easy way, using instructions a...
How to extract one column of a csv file
...
You could use awk for this. Change '$2' to the nth column you want.
awk -F "\"*,\"*" '{print $2}' textfile.csv
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...
Insert a row to pandas dataframe
...
Just assign row to a particular index, using loc:
df.loc[-1] = [2, 3, 4] # adding a row
df.index = df.index + 1 # shifting index
df = df.sort_index() # sorting by index
And you get, as desired:
A B C
0 2 3 4
1 5 6 7
2 7 8 9
See in Pandas documentation Indexing: Se...