Cookbook: Difference between revisions

Cookbook (edit)

Revision as of 00:02, 11 November 2012

132 bytes added , 11 November 2012

fix template

Carandraug

Bureaucrats, Administrators

659

edits

@@ Line 82: / Line 82: @@
 outargs = nthargout (1:3, @myfunc)
 </syntaxhighlight>}}
+=== Create a text table with fprintf===
+(a.k.a. A funny formatting trick with fprintf found by chance)
+Imagine that you want to create a text table with fprintf with 2 columns of 15 characters width and both right justified. How to do this thing?
+That's easy:
+If the variable Text is a cell array of strings (of length <15) with two columns and a certain number of rows, simply type for the kth row of Text
+{{Code||<syntaxhighlight lang="octave" style="font-size:13px">
+ fprintf('%15.15s | %15.15s\n', Text{k,1}, Text{k,2});
+</syntaxhighlight>}}
+The syntax '%<n>.<m>s' allocates '<n>' places to write chars and display the '<m>' first characters of the string to display.
+Example:
+{{Code|Example create a text table with fprintf|<syntaxhighlight lang="octave" style="font-size:13px">
+ octave:1> Text={'Hello','World'};
+ octave:2> fprintf('%15.15s | %15.15s\n', Text{1,1}, Text{1,2})
+          Hello |           World
+</syntaxhighlight>}}
+===Load comma separated values (*.csv) files===
+{{Code|Load comma separated values files|<syntaxhighlight lang="octave" style="font-size:13px">
+A=textread("file.csv", "%d", "delimiter", ",");
+B=textread("file.csv", "%s", "delimiter", ",");
+inds = isnan(A);
+B(!inds) = num2cell(A(!inds))
+</syntaxhighlight>}}
+This gets you a 1 column cell array. You can reshape it to the original size by using the <code>reshape</code> function
+The next version of octave (3.6) implements the <code>CollectOutput</code> switch as seen in example 8 here:                    http://www.mathworks.com/help/techdoc/ref/textscan.html
+Another option is to use the function <code>csvread</code>, however this function can't handle non-numerical data.
+===Using variable strings in commands===
+For example, to plot data using a string variable as a legend:
+Option 1 (simplest):
+{{Code|Using variable strings in commands. op1|<syntaxhighlight lang="octave" style="font-size:13px">
+legend = "-1;My data;";
+plot(x, y, legend);
+</syntaxhighlight>}}
+Option 2 (to insert variables):
+{{Code|Using variable strings in commands. op2|<syntaxhighlight lang="octave" style="font-size:13px">
+plot(x, y, sprintf("-1;%s;", dataName));
+</syntaxhighlight>}}
+Option 3 (not as neat):
+{{Code|Using variable strings in commands. op3|<syntaxhighlight lang="octave" style="font-size:13px">
+legend = 'my legend';
+plot_command = ['plot(x,y,\';',legend,';\')'];
+eval(plot_command);
+</syntaxhighlight>}}
+These same tricks are useful for reading and writing data files with unique names, etc.
 == Mathematics ==
+=== Test if a number is a integer ===
+There's several menthods to do this. The simplest method is probably {{Codeline|<nowiki>fix (x) == x</nowiki>}}
 === Find if a number is even/odd ===
 ==== Problem ====
@@ Line 191: / Line 254: @@
 get (0, "screensize")
 </syntaxhighlight>}}
-== Input/Output ==
-=== Create a text table with fprintf===
-(a.k.a. A funny formatting trick with fprintf found by chance)
-Imagine that you want to create a text table with fprintf with 2 columns of 15 characters width and both right justified. How to do this thing?
-That's easy:
-If the variable Text is a cell array of strings (of length <15) with two columns and a certain number of rows, simply type for the kth row of Text
-{{Code||<syntaxhighlight lang="octave" style="font-size:13px">
- fprintf('%15.15s | %15.15s\n', Text{k,1}, Text{k,2});
-</syntaxhighlight>}}
-The syntax '%<n>.<m>s' allocates '<n>' places to write chars and display the '<m>' first characters of the string to display.
-Example:
-{{Code|Example create a text table with fprintf|<syntaxhighlight lang="octave" style="font-size:13px">
- octave:1> Text={'Hello','World'};
- octave:2> fprintf('%15.15s | %15.15s\n', Text{1,1}, Text{1,2})
-          Hello |           World
-</syntaxhighlight>}}
-===Load comma separated values (*.csv) files===
-{{Code|Load comma separated values files|<syntaxhighlight lang="octave" style="font-size:13px">
-A=textread("file.csv", "%d", "delimiter", ",");
-B=textread("file.csv", "%s", "delimiter", ",");
-inds = isnan(A);
-B(!inds) = num2cell(A(!inds))
-</syntaxhighlight>}}
-This gets you a 1 column cell array. You can reshape it to the original size by using the <code>reshape</code> function
-The next version of octave (3.6) implements the <code>CollectOutput</code> switch as seen in example 8 here:                    http://www.mathworks.com/help/techdoc/ref/textscan.html
-Another option is to use the function <code>csvread</code>, however this function can't handle non-numerical data.
-===Using variable strings in commands===
-For example, to plot data using a string variable as a legend:
-Option 1 (simplest):
-{{Code|Using variable strings in commands. op1|<syntaxhighlight lang="octave" style="font-size:13px">
-legend = "-1;My data;";
-plot(x, y, legend);
-</syntaxhighlight>}}
-Option 2 (to insert variables):
-{{Code|Using variable strings in commands. op2|<syntaxhighlight lang="octave" style="font-size:13px">
-plot(x, y, sprintf("-1;%s;", dataName));
-</syntaxhighlight>}}
-Option 3 (not as neat):
-{{Code|Using variable strings in commands. op3|<syntaxhighlight lang="octave" style="font-size:13px">
-legend = 'my legend';
-plot_command = ['plot(x,y,\';',legend,';\')'];
-eval(plot_command);
-</syntaxhighlight>}}
-These same tricks are useful for reading and writing data files with unique names, etc.