Help:Sorting

Tables can be made sortable via using.

A sortable table is identified by the arrows in each of its header cells. Clicking on the arrows will cause the table rows to sort based on the selected column, in ascending order first, and subsequently toggling between ascending and descending order. Links and other wiki markup are not possible in the headers of sortable tables.

Sort modes
The sort modes (the s, which, in addition to the choice "ascending" or "descending", determine the sorting order) are as follows in the given order (as soon as there is a match, subsequent criteria are not applicable; for example, 24-12-2007 is a date, not a number). For the criteria, tags (, ,  , etc.) are ignored.
 * date
 * criterion: the first non-blank element is of the form "dd-dd-dddd", "dd-dd-dd", or "dd aaa dddd"; or, in the last case, text follows ending with "sm=d" (without the quotes; it stands for "sort mode = date").
 * order: the string abcdefghij (length 10) is sorted as ghijdeab; the string abcdefgh (length 8) is sorted as 19ghdeab if gh>=50 (string comparison) and 20ghdeab otherwise (i.e., the assumed format is DD-MM-YYYY or DD-MM-YY); and the string "dd aaa dddd" is sorted chronologically with aaa as an abbreviated month name.
 * "currency" (this mode can be useful for other data also)
 * criterion: the first non-blank element starts with $, £, €, or ¥, or the element ends with "sm=c" (without the quotes; it stands for "sort mode = currency").
 * order: numeric, ignoring these symbols and all ordinary letters and commas, but not spaces; note that scientific notation cannot be used, as e and E are removed
 * numeric
 * criterion: the first non-blank element consists of just digits, decimal points, commas, spaces, "+", "-", possibly followed by "e" or "E" and a string consisting of "+", "-", digits, possibly followed by "&times;10" and a string consisting of "+", "-", digits (the latter is for the purpose of using hidden followed by visible superscript notation of ); or the element ends with "sm=n" (without the quotes; it stands for "sort mode = numeric").
 * order: if the string starts with a number (where spaces and nbsp's at the start are ignored) the order is numeric according to the first number in the string (parseFloat is applied) after removing the commas, if any; if it does not (parseFloat returns ), the element is positioned like 0.
 * string
 * criterion: all other cases; to avoid one of the other modes, start, for example, with a hidden "&"; this can be done conveniently with sms, which also allows more hidden text, as the sortkey; while the similar templates above are called at the end of a table element, call this one at the start.
 * order: after conversion of capitals to lowercase the order is - partial list showing the order: !"#$%&'*+,-./09:;<=>?@[\]^_'az{|}~é – (see also below; a blank space comes before every other character; an  code counts as a space; two adjacent ordinary blank spaces count as one; for multiple blank spaces one can use nbsps or alternate nbsps and ordinary blank spaces).

The sort mode is determined by the table element that is currently in the first non-blank row below the header. (To minimize the deviation from wikibits.js, the code "ns=.." works in the first element below the header instead of in the header.) In the case of different data types within one column (according to the criteria mentioned above) the sort mode may change after sorting, which can give a cycle of four or even more instead of two. This is confusing and gives undesired sorting orders, so that can better be avoided. However, it can be complicated to assess whether an element can ever be at the top after any sorting operations on the same and other columns, and this can also change after deleting a row, or adding a column. Therefore it is wise to make sure that every element matches the criterion for the required data type. Using a row template this can be done very conveniently.

Examples
Text after a number (for example, a footnote) does not affect the sorting order, if the sorting mode is numeric. However, if the number at the top has text after it, this makes the sorting mode alphabetic, unless it ends with a (typically invisible) "sm=n".

The example with "a" gives alphabetic sorting; that with "e" ditto, the data are not mistaken for numbers in scientific format.

The first example demonstrates that text is positioned at zero, and that e.g. e3 for 1000 is not allowed; use 1e3 instead. Using exp, a number in scientific notation can be displayed with a superscript, while still allowing numeric sorting (compare the method described in the next section). It also shows that "-" should be used, not "−". The first element "12 or 13 sm=n" has a visible "sm=n", although it is normally made invisible; when this element is at the top, numeric sorting mode applies.

The second example shows that expressions are not sorted according to their evaluated value, but according to the first number.

The third example shows that a percentage is accepted for numeric sorting mode, but ignored in the actual sorting, so if a column contains percentages, all numbers have to be written as a percentage.

The fourth example shows again that "ca. 12" sorts at 0, as opposed to 12 with some text after it, which sorts at 12. In the latter case an invisible "sm=n" needs to be put at the end, in case such an element arrives at the top of a column, which would otherwise cause alphabetic sorting mode.

Sortable version of, using smn to specify numeric sort mode:

Excluding the last row from sorting
Sometimes it is helpful to exclude the last row of a table from the sorting process.

This can be achieved using  on the desired table row (line starting with  ).

Wiki markup

What it looks like in your browser

Issues
Please note that only one row can be marked with. Doing otherwise results in the marked rows being sorted with each other, which usually is not the intended behavior.

Making a column unsortable
If you want a specific column not to be sortable, specify  in the attributes of its header cell.

Wiki markup

What it looks like in your browser

Sorting with hidden sortkey
If necessary, one can apply sorting using a sortkey which due to CSS is not displayed:

Javascript sorting is based on the text inside and outside the tags, without the tags themselves. A hidden sortkey can be put at the start. Both in the case of alphabetic and that of numeric sorting the first parts determine the order. For the purpose of a hidden sortkey for numeric sorting, the criterion for the item at the top being a number has been adapted: ignoring span and sup tags, it can be a number followed by "×10" and an exponent (use the same cross sign). This format is, for example, produced by exp. A hidden sortkey for alphabetic sorting does not have such restrictions.

Alphabetic sorting with hidden sortkey
The sortkey comes at the start and is separated from the displayed text in such a way that the latter does not affect the sorting order. For example, if a sortkey system is used where there are no blank spaces in any sortkey, then a blank space can be used for separation. If a single blank space is possible in a sortkey, two nbsps can be used. For table elements for which the text to be displayed is equal to the sortkey, no duplication is needed, of course.

If the text inside and outside the tags together is of a form that would cause a sorting mode other than alphabetic (if and when the element is at the top), a character can be appended at the end of the sortkey to avoid this, again making sure it does not affect the sorting order by putting a space or two nbsps. This can be dispensed with if the element can never be at the top, but this can be complicated to assess as that can be caused by sorting other columns, with varying sorting modes, and it can change when deleting a row, adding a column, etc.

Instead of "display=none" another way is using a font color equal to the background, for example 999 gives "999 ". With this method the hidden code can be seen in selected text (using the mouse). Also the hidden text is included when copying the rendered text. The first may be an advantage or a disadvantage, the second seems only a disadvantage. A complication is also that if a user uses a background color different from the default, the specified text color may not match it; to make sure they are the same the background color can be specified also.

Unsuitability of padding with no-break spaces
The effect of left-padding with, which render as blank spaces, depends on the browser: in IE they are (unlike actual blank spaces) counted for sorting as leading blank spaces, so in a list of numbers with text (for which the alphabetic sorting mode applies) they could be used to equalize the number of characters before the explicit or implicit decimal separator. However, in Firefox they are ignored for the purpose of sorting.

Padding with zeros
Example:
 * 000000

Formatnum can be combined with padleft:

Integer:

299,792,458 gives:


 * 299,792,458

Real:

0.000000 gives:


 * 0.000000

Alphabetic sortkey for numeric sorting
Numeric sort mode can be forced with smn (see above). Numbers preceded with text are sorted like 0; to avoid that the text can be preceded by a hidden copy of the number.

If for some reason one wants to use alphabetic sort mode for numbers, one can construct a hidden alphabetic sortkey for this purpose. This can be done for all numbers between -1e100 and 1e100 in arbitrary precision as follows: In the following the left column shows the code for alphabetic sorting, where cryptic followed by the regular notation. The second column contains the same (hence sorting the same), but with code hidden with CSS. The third column shows the corresponding plain numbers with thousands separators, equal to what the second column shows, now using numeric sorting mode.
 * where scientific notation is used, it is normalized such that the absolute value of the mantissa is between 1 and 10; the exponent is put first
 * scientific notation is used for all negative numbers, and all positive numbers outside some interval (below: 1e-9 to 1e9), and not inside that interval
 * where the absolute value of the exponent and/or the mantissa is a decreasing function of the number, the notation uses its complement with respect to 99 for exponents and 10 for mantissas; the code "c" is added in these cases
 * numbers 0 &le; x < 1000 get a "+" in front
 * positive numbers in scientific notation with a negative exponent get "+0" in front
 * spaces inside the code and &-signs in front are added where needed:
 * for numbers not in scientific notation the positions of all explicit and implicit decimal points are aligned
 * for the starting position, i.e. the position of the first "-", "+", or "e", of other numbers, see the example table
 * no code should satisfy the criterion for numeric sorting mode (below we have always either an ampersand or two letters e): although this matters only for the element at the top, any element might arrive at the top due to sorting another column

Dates
The sort mode is based on the rendered format; in the case of links: the labels, not the targets (though including any content hidden by "display:none").

Date sort mode:

One of the formats allowed for the date sort mode is produced by the Mediawiki's date-formatting feature in the right combination of preference and wikitext format: we need to use in the wikitext the format dd mmm yyyy (done in the example) and either no preference or preference dmy, or use with preference dmy one of the formats mmm ddyyyy, yyyymmm dd, or yyyydd mmm.

Incomplete dates:
 * 00 Jan 2007
 * 00 Mar 2007

String sort mode:

String sort mode provides chronological sorting for dates formated as & YYYY-MM-DD; the hidden "&" avoids numeric sort mode.

Also we can hide the YYYY-MM-DD and put after that any choice of displayable text, including Mediawiki date formatting.

If a table column contains any or all incomplete dates, this will not cause sorting problems. If only a year and month are given, that incomplete date is positioned alphabetically before the first day of the month in question. Likewise, if only a year is given, the date is positioned before the first month or day given for that year.

If at some point (i.e., after possible previous sorting) the form  is at the top with a non-negative year, sorting would be numerical; in this case, after toggling between ascending and descending there would be no proper sorting within each year (because parsefloat is applied, finding the first number in the string, and basing sorting on only that number). Also, years BC would not be sorted properly. Therefore, alphabetic sorting has to be enforced. This can be done by putting a non-displayed character after the year, separated by a space.

Secondary sortkey
If a column contains a value multiple times then sorting the column preserves the order of the rows within each subset that has the same value in that column. Thus sorting based on a primary, secondary, tertiary, etc. sortkey can be done by sorting the least-significant sortkey first, etc.

First click on column Alphabet and then on Numbers, you'll see that the ordering is on Numbers (1), Alphabet (2).

Limitations
Javascript sorting may not work properly on tables with cells extending over multiple rows and/or columns. Also, while cells can be empty, they should not be missing at the end of a row. In these cases sometimes the table gets messed up when attempting to sort, while other times some of the sorting buttons work while others don't.

Controlling sorting and display
Text undesired for sorting but needed for display:
 * In numeric sorting mode, this text (e.g. footnotes) needs to be put after the number, and an invisible "sm=n" after that.
 * In date sorting mode, this text needs to be put in a separate column; in the case of a cell containing a range of dates or numbers (e.g. from .. to ..), text in surplus of what is required for sorting is put in the extra column. If the first part of the text is used for sorting, then the extra column needs to be the following one; conversely, if the last part of the text is used for sorting, then the extra column needs to be the previous one; depending on the table format, this dividing of an item over two cells may look ugly.
 * In alphabetic sorting, any footnotes etc. do not require a separate column; they can simply be put at the end of the element.

Text undesired for display but needed for sorting:
 * can be put as hidden text in the column to be sorted

Combining the two, we can have displayed text independent of text used for sorting, by fully hiding the latter, and fully putting the former in a separate column (in date sorting mode and numeric sorting mode) or in the same column after the hidden text (in alphabetic sorting). Fully putting the displayed text in a separate column may look ugly if it is not done consistently for a whole column, but only for elements that require this (e.g. if most entries in a column are single numbers, but some are ranges).

Static column
A static column, e.g. with row numbers, can be obtained with two side-by-side tables with for each row the same height set in both tables:

The style can be adjusted to make it appear as a single table. If for some row the height of that row is too small for the text in a cell on one of the sides, the browser increases it, and there is no longer a match.

Sorting the wikitext of a table
Unfortunately it does not seem possible to directly and automatically sort the wikitext itself, according to one of the sortkeys. This would, after saving, directly produce a table sorted as required.

However, if for a given table, we make an auxiliary sortable table rendering as wikitext for the original table, we can sort the wikitext of the original table.

Example:

Original table:

Auxiliary table:

After copying the rendered text to the edit box, and deleting the header line, this renders as:

Alphabetic sorting order
The two-character entries such as A1 demonstrate that A and a are at the same position.

Browser issues
With Safari on Mac-OSX a table can only be sorted by the first column: all sort buttons have the effect that only the leftmost one is supposed to have.