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Adding 'serial' to existing column in Postgres
I have a small table (~30 rows) in my Postgres 9.0 database with an integer ID field (the primary key) which currently contains unique sequential integers starting at 1, but which was not created using the 'serial' keyword.
...
How to round a number to n decimal places in Java
...ngMode(RoundingMode.CEILING);
for (Number n : Arrays.asList(12, 123.12345, 0.23, 0.1, 2341234.212431324)) {
Double d = n.doubleValue();
System.out.println(df.format(d));
}
gives the output:
12
123.1235
0.23
0.1
2341234.2125
EDIT: The original answer does not address the accuracy of th...
Renaming columns in pandas
...he .columns attribute:
>>> df = pd.DataFrame({'$a':[1,2], '$b': [10,20]})
>>> df.columns = ['a', 'b']
>>> df
a b
0 1 10
1 2 20
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...
python setup.py uninstall
...eworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/my_module-0.1.egg/ on macOS. It has no files, but Python will still import an empty module:
>>> import my_module
>>> my_module.__file__
None
Once deleted, Python shows:
>>> import my_module
Traceback (mos...
How to read the content of a file to a string in C?
...-codes for fseek, ftell and fread. (omitted for clarity).
char * buffer = 0;
long length;
FILE * f = fopen (filename, "rb");
if (f)
{
fseek (f, 0, SEEK_END);
length = ftell (f);
fseek (f, 0, SEEK_SET);
buffer = malloc (length);
if (buffer)
{
fread (buffer, 1, length, f);
}
fclo...
Making heatmap from pandas DataFrame
...5, 4)), index=index, columns=columns)
plt.pcolor(df)
plt.yticks(np.arange(0.5, len(df.index), 1), df.index)
plt.xticks(np.arange(0.5, len(df.columns), 1), df.columns)
plt.show()
This gives:
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Check if an element is present in an array [duplicate]
...
1044
ECMAScript 2016 incorporates an includes() method for arrays that specifically solves the prob...
How to sort a dataFrame in python pandas by two or more columns?
...
490
As of the 0.17.0 release, the sort method was deprecated in favor of sort_values. sort was comp...
Sort array of objects by single key with date value
... use Array.sort.
Here's an example:
var arr = [{
"updated_at": "2012-01-01T06:25:24Z",
"foo": "bar"
},
{
"updated_at": "2012-01-09T11:25:13Z",
"foo": "bar"
},
{
"updated_at": "2012-01-05T04:13:24Z",
"foo": "bar"
}
]
arr.sort(function(a, b) {
v...
How can I determine the direction of a jQuery scroll event?
...
704
Check current scrollTop vs previous scrollTop
var lastScrollTop = 0;
$(window).scroll(functio...