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I need to put an index on a materialized view. What is the method? I do not know how often the stats are refreshed and would this effect it performance of the index or view?

Archived from the original on 4 December Each archive has an infomation page describing the list. All there is left to do is to create a linked server connection to PostgreSQL database directly from SQL Server Management Studio, exposing a collection of objects tables and views on the public schema.

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I need to put an index on a materialized view. What is the method? I do not know how often the stats are refreshed and would this effect it performance of the index or view?

Try a smaller data and see if the program still crashes. How to build a dynamic library. The easiest way is to use Makefile. Here is the example using Visual Studio Rename the dll file to libsvm. On some systems e. Is this a problem and how to disable the warning message? If you are using a version before 3.

For portability, we use only features defined in ISO C Note that features in ISO C99 may not be available everywhere. Even the newest gcc lacks some features in C99 see http: If the situation changes in the future, we might consider using these newer features. Hence a data with attributes 1 0 2 0 is represented as 1: What if my data are non-numerical?

Currently libsvm supports only numerical data. You may have to change non-numerical data to numerical. For example, you can use several binary attributes to represent a categorical attribute. Why do you consider sparse format? Will the training of dense data be much slower? This is a controversial issue.

The kernel evaluation i. Simplicity of the code is another concern. Right now we decide to support the sparse format only.

Why sometimes the last line of my data is not read by svm-train? So please press enter in the end of your last line. Is there a program to check if my data are in the correct format?

The svm-train program in libsvm conducts only a simple check of the input data. To do a detailed check, after libsvm 2. May I put comments in data files? We don't officially support this. It depends on your data format. Labels are in the first column. The following steps produce a file in the libsvm format. Alternatively, you can use convert. The output of training C-SVM is like the following.

What do they mean? More details are in libsvm document. Can you explain more about the model file? In the model file, after parameters and other informations such as labels , each line represents a support vector. Support vectors are listed in the order of "labels" shown earlier.

For example, if there are 4 classes, the file looks like: Should I use float or double to store numbers in the cache? We have float as the default as you can store more numbers in the cache. In general this is good enough but for few difficult cases e.

C very very large where solutions are huge numbers, it might be possible that the numerical precision is not enough using only float.

Does libsvm have special treatments for linear SVM? You can either Use small C only. We have shown in the following paper that after C is larger than a certain threshold, the decision function is the same.

Asymptotic behaviors of support vector machines with Gaussian kernel. Neural Computation , 15 , Check liblinear , which is designed for large-scale linear classification. The number of free support vectors is large. What should I do? This usually happens when the data are overfitted. If attributes of your data are in large ranges, try to scale them. Then the region of appropriate parameters may be larger.

Note that there is a scale program in libsvm. Should I scale training and testing data in a similar way? Yes, you can do the following: On windows sometimes svm-scale. In general this does not happen, but we have observed in some rare situations, the output of svm-scale. Please let us know if this happens as at this moment we don't clearly see how to fix the problem. Does it make a big difference if I scale each attribute to [0,1] instead of [-1,1]?

For the linear scaling method, if the RBF kernel is used and parameter selection is conducted, there is no difference. Assume Mi and mi are respectively the maximal and minimal values of the ith attribute. Though the performance is the same, the computational time may be different. For data with many zero entries, [0,1]-scaling keeps the sparsity of input data and hence may save the time.

The prediction rate is low. How could I improve it? Try to use the model selection tool grid. To see the importance of model selection, please see our guide for beginners: A practical guide to support vector classification [Go Top] Q: My data are unbalanced. Could libsvm handle such problems? Yes, there is a -wi options. Note that this -w option is for C-SVC only. Basically they are the same thing but with different parameters. The range of C is from zero to infinity but nu is always between [0,1].

A nice property of nu is that it is related to the ratio of support vectors and the ratio of the training error.

The program keeps running without showing any output. You may want to check your data. It cannot be separated. In addition, you have to remove empty lines. The program keeps running with output, i. In theory libsvm guarantees to converge. Therefore, this means you are handling ill-conditioned situations e.

You may get better numerical stability by replacing typedef float Qfloat; in svm. However, this means fewer elements can be put in the kernel cache. The training time is too long. For large problems, please specify enough cache size i. Slow convergence may happen for some difficult cases e. You can try to use a looser stopping tolerance with -e. If that still doesn't work, you may train only a subset of the data. You can use the program subset.

If you have extremely large data and face this difficulty, please contact us. We will be happy to discuss possible solutions. When using large -e, you may want to check if -h 0 no shrinking or -h 1 shrinking is faster. Obviously, the reversed limitations still apply.

To access the index as though you were iterating forward over a reversed copy of the collection, use i - If you need the index, the simplest way is to subtract the index returned by enumerate reversed from len Assuming task is to find last element that satisfies some condition in a list i.

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site the association bonus does not count. Would you like to answer one of these unanswered questions instead?

Traverse a list in reverse order in Python Ask Question. So I can start from len collection and end in collection[0]. Sorry, I forgot to mention I also want to be able to access the loop index. Use the built-in reversed function: Greg Hewgill k No copy is created, the elements are reversed on the fly while traversing!

Greg Hewgill No, it's an iterator over the original, no copy is created! To avoid the confusion: If you need to modify the list use alist.

This is slightly slower than using reversed, at least under Python 2. This works for query objects, reversed does not. How this answer works: I tested this as well python 2. Triptych k 29 This reduces possible confusion, especially when viewing operational or strategic level maps.

In pharmacy , Roman numerals are used in some contexts, including S to denote "one half" and N to mean "nothing". In photography , Roman numerals with zero are used to denote varying levels of brightness when using the Zone System.

In seismology , Roman numerals are used to designate degrees of the Mercalli intensity scale of earthquakes. In sport the team containing the "top" players and representing a club or a school at the highest level in say rugby union is often called the "1st XV", while a cricket or American football team for younger or less experienced players might be the "3rd XI".

In tarot , Roman numerals with zero are used to denote the cards of the Major Arcana. In theology and biblical scholarship , the Septuagint is often referred to as LXX , as this translation of the Old Testament into Greek is named for the legendary number of its translators septuaginta being Latin for "seventy".

Some uses that are rare or never seen in English speaking countries may be relatively common in parts of continental Europe. Capital or small capital Roman numerals are widely used in Romance languages to denote centuries , e.

On the other hand, in Slavic languages in Central Europe , like most Germanic languages , one writes " Mixed Roman and Arabic numerals are sometimes used in numeric representations of dates especially in formal letters and official documents, but also on tombstones.

The month is written in Roman numerals, while the day is in Arabic numerals: Roman numerals are sometimes used to represent the days of the week in hours-of-operation signs displayed in windows or on doors of businesses, [30] and also sometimes in railway and bus timetables. Monday, taken as the first day of the week, is represented by I. Sunday is represented by VII. The hours of operation signs are tables composed of two columns where the left column is the day of the week in Roman numerals and the right column is a range of hours of operation from starting time to closing time.

Note that the listing uses hour time. Roman numerals may also be used for floor numbering. The apartment on the ground floor is indicated as huis. In Italy, where roads outside built-up areas have kilometre signs , major roads and motorways also mark metre subdivisionals, using Roman numerals from I to IX for the smaller intervals. The sign " IX 17" thus marks kilometre A notable exception to the use of Roman numerals in Europe is in Greece, where Greek numerals based on the Greek alphabet are generally used in contexts where Roman numerals would be used elsewhere.

The number zero does not have its own Roman numeral, but the word nulla the Latin word meaning "none" was used by medieval scholars in lieu of 0. Dionysius Exiguus was known to use nulla alongside Roman numerals in On coins , many of which had values that were duodecimal fractions of the unit as , they used a tally-like notational system based on twelfths and halves.

Six twelfths one half was abbreviated as the letter S for semis "half". Uncia dots were added to S for fractions from seven to eleven twelfths, just as tallies were added to V for whole numbers from six to nine. The arrangement of the dots was variable and not necessarily linear. The Latin words sextans and quadrans are the source of the English words sextant and quadrant. A number of systems were developed for the expression of larger numbers that cannot be conveniently expressed using the normal seven letter symbols of conventional Roman numerals.

Another system is the vinculum , in which conventional Roman numerals are multiplied by 1, by adding an "bar" or "overline". Any hundreds, tens or units in the number are written in ordinary Roman numerals - but instead of M , MM or MMM , "barred" notation is used to express the thousands - which greatly expands the range of numbers expressible. Another inconsistent medieval usage was the addition of vertical lines or brackets before and after the numeral to multiply it by 10 or In combination with the overline the bracketed forms might be used to raise the multiplier to say ten or one hundred thousand, thus:.

Through all this, and whether any kind of vinculum notation or "barring" needs to be revived or not, this needs to be distinguished from the custom, once very common, of adding both underline and overline to a Roman numeral, simply to make it clear that it is a number, e. From Wikipedia, the free encyclopedia. Redirected from Roman numeral. Numbers in the Roman numeral system. For a description of numeric words in Latin, see Latin numerals linguistics.

Illustrated Introduction to Latin Epigraphy. University of California Press. Alphabetic symbols for larger numbers, such as Q for ,, have also been used to various degrees of standardization.

Essential Math and Calculations for Pharmacy Technicians. Number Smart Quest for Mastery: What is its significance? Roman Numerals…not quite so simple. More of the straight dope. Longmans, Green, and Co.

In Hornblower, Simon; Spawforth, Anthony. Oxford Classical Dictionary 3rd ed. The Revised Latin Primer. Museum's North Entrance ".