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Multidimensional Array [][] vs [,] [duplicate]
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One is an array of arrays, and one is a 2d array. The former can be jagged, the latter is uniform.
That is, a double[][] can validly be:
double[][] x = new double[5][];
x[0] = new double[10];
x[1] = new double[5];
x[2] = new double[3];
x[3] = new d...
Find the max of two or more columns with pandas
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You can get the maximum like this:
>>> import pandas as pd
>>> df = pd.DataFrame({"A": [1,2,3], "B": [-2, 8, 1]})
>>> df
A B
0 1 -2
1 2 8
2 3 1
>>> df[["A", "B"]]
A B
0 1 -2
1 2 8
2 3 1
>>> df[["A", "B"]].max(axis=1)
0...
What do people find difficult about C pointers? [closed]
...ve some pretty fundemental issues when getting their heads around pointers and pointer arithmetic.
29 Answers
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Handling optional parameters in javascript
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You can know how many arguments were passed to your function and you can check if your second argument is a function or not:
function getData (id, parameters, callback) {
if (arguments.length == 2) { // if only two arguments were supplied
if (Object.prototype.toString.call(param...
Splitting string into multiple rows in Oracle
I know this has been answered to some degree with PHP and MYSQL, but I was wondering if someone could teach me the simplest approach to splitting a string (comma delimited) into multiple rows in Oracle 10g (preferably) and 11g.
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what exactly is device pixel ratio?
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Short answer
The device pixel ratio is the ratio between physical pixels and logical pixels. For instance, the iPhone 4 and iPhone 4S report a device pixel ratio of 2, because the physical linear resolution is double the logical linear resolution.
Physical resolution: 960 x 640
Logical resolutio...
find: missing argument to -exec
I was helped out today with a command, but it doesn't seem to be working. This is the command:
10 Answers
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How does one reorder columns in a data frame?
...mns like so df[,c(1,2,3,4)].
Note the first comma means keep all the rows, and the 1,2,3,4 refers to the columns.
To change the order as in the above question do df2[,c(1,3,2,4)]
If you want to output this file as a csv, do write.csv(df2, file="somedf.csv")
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Generate a heatmap in MatPlotLib using a scatter data set
...ou can use numpy's histogram2d function:
import numpy as np
import numpy.random
import matplotlib.pyplot as plt
# Generate some test data
x = np.random.randn(8873)
y = np.random.randn(8873)
heatmap, xedges, yedges = np.histogram2d(x, y, bins=50)
extent = [xedges[0], xedges[-1], yedges[0], yedges[...
What are the differences between Clojure, Scheme/Racket and Common Lisp?
...ew, if possible, covering topics such as syntax, characteristics, features and resources.
4 Answers
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