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How to use the toString method in Java?
Can anybody explain to me the concept of the toString() method, defined in the Object class? How is it used, and what is its purpose?
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How do you sort a dictionary by value?
I often have to sort a dictionary, consisting of keys & values, by value. For example, I have a hash of words and respective frequencies, that I want to order by frequency.
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How do I check if an index exists on a table field in MySQL?
I've needed to Google this a couple times, so I'm sharing my Q/A.
10 Answers
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Linear Regression and group by in R
I want to do a linear regression in R using the lm() function. My data is an annual time series with one field for year (22 years) and another for state (50 states). I want to fit a regression for each state so that at the end I have a vector of lm responses. I can imagine doing for loop for each ...
Find an element in a list of tuples
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If you just want the first number to match you can do it like this:
[item for item in a if item[0] == 1]
If you are just searching for tuples with 1 in them:
[item for item in a if 1 in item]
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Format JavaScript date as yyyy-mm-dd
I have a date with the format Sun May 11,2014 . How can I convert it to 2014-05-11 using JavaScript?
42 Answers
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Parse rfc3339 date strings in Python? [duplicate]
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You can use dateutil.parser.parse to parse strings into datetime objects.
dateutil.parser.parse will attempt to guess the format of your string, if you know the exact format in advance then you can use datetime.strptime whic...
How to plot two columns of a pandas data frame using points?
...ot values from one column versus the values from another column. Fortunately, there is plot method associated with the data-frames that seems to do what I need:
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Is there a numpy builtin to reject outliers from a list
Is there a numpy builtin to do something like the following? That is, take a list d and return a list filtered_d with any outlying elements removed based on some assumed distribution of the points in d .
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How can I display just a portion of an image in HTML/CSS?
Let's say I want a way to display just the the center 50x50px of an image that's 250x250px in HTML. How can I do that. Also, is there a way to do this for css:url() references?
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