How do I filter a DataFrame using a value in a string column?
I have a CSV file containing records. Some columns are numbers, others are strings.
The examples in the tutorials are good for filtering on numbers but I can't see how to filter using a string.

ie I have 1300 records with ID, Name, Region, enrolments, ...
enrolments is a number and I can filter on that.
Region is a column of strings. I want to filter on that and work with all records from a specific region.

Thanks,
David Moss

I upgraded my OS from Ubuntu 14.04 to Ubuntu 16.04.

When attempting to start maple, I get

Licensing error:-9,57

What does this mean?

Dear all,

I am looking at the help page for reading json files, but it is too advanced for me to understand...

Can anyone give an easy example where a json file is read into a variable and printing the data structure?

Hugs,
Louise =)

I can draw a triangle using the geomtry package:

point(A, 0, 0), point(B, 2, 1), point(C, 2, 0); triangle(T, [A, B, C])
d := draw(T, axes = none, color = black); t := textplot([[.227, 0.60e-1, typeset(theta)], [1.1, 0, typeset(k__2)]])
display(t,d)

The result is as below.

I would like to place the label k2 below the line but negative numbers do not work. I would like to put a label k1 to the right of
the opposite side but there is no room,  and finally I would like to put sqrt(k1^2+k2^2) above the hypotenuse slanted to be
parallel with the hypotenuse if possible.

  Hi, there

How can I draw the excircles, incircles,circumcircle and their centers of a triangle simultaneously with maple13 in a geometric plot? please specify the commands.

many thanks for your help

M.R.Yegan

Download operator.mw

Regards

I defined a procedure, OrderB(0,b,c), that essentially determines the order of a group that is defined by 2 parameters (the first parameter is always zero), so the output is an integer and the procedure is defined for every integer value of both parameters. I wanted to structure the outputs into a matrix with columns that represent one parameter and rows that represent the other. However, whenever I try to apply a method of defining the matrix, Maple returns the values of the procedure and then gives me an empty matrix.

>f:=proc (i, j) -> OrderB(0, i, j+3);
>Matrix(3, f);
                               1
                               4
                               1
                               1
                               4
                               1
                               1
                               4
                               1
               [NULL,NULL...]


I tried a second method where I defined a set s such that:

s:={(0,0)=OrderB(0,0,0) , (0,1)=OrderB(0,0,1).....}

but upon execution, maple returns:

1
4
1
....
s:={(0,0)=( ), (0,1)=( )...}

Please Help. I don't know what I'm mising in the code that is keeping Maple from putting the outputs of my procedure into the matrix.

Been working on a diffy q project, new to maple here. Any help is appreciated. Keep getting a similar error.

"Error, (in dsolve/numeric/type_check) insufficient initial/boundary value information for procedure defined problem"

I thought I gave it initial values?

link to screenshot of the error bellow:

http://i.imgur.com/YVE1x7e.jpg

Hi,

For the paste several years, I have occasionally tested Maple on a simple integral,

simplify(int( exp(-I*k*x)/cosh(x), x=-infinity..infinity) assuming k,real);

The integral is returned unevaluated. There is no problems related to the complex exponential,

since also e.g.

simplify(int( cos(k*x)/cosh(x), x=0..infinity) assuming k,real);

and other variants are not evaluated.

Turning to the inbuilt fourier function (inttrans package) also does not work.

Evaluating laplace(1/cosh(x),x,s), and subsequently substituting s=I*k and s=-I*k and summing WORKS,

but gives (unnecessarily) an ugly result which it cannot simplify.

Finally, subtracting the (manually simplified) correct expression and simplifying gives 0 as

verification. I can not see any technical explanation for this bug.

Hi everybody,

how about a little arithmetical challenge?

known quantities : Z, t, epsilon : reals

let W = X+Y*t    X, Y integers, t real (t with unlimited precision)

let W = Z + epsilon (epsilon < 1/W), Z real (Z with unlimited precision)

W and Z have same decimal expansion ( W - Integerpart[W], Z - IntegerPart[Z] ), up to a certain "rank" (determined by the precision : epsilon)

Y*t and Z have same decimal expansion, up to a certain "rank".

The problem : build an algorithm to find the integer Y, using the "usable" decimal expansion of Z.

Thanks in advance for your contributions!

I am trying to find the root of an equation. The problem is, I keep getting the error

"Error, (in fsolve) Can't handle expressions with typed procedures"

and 

Warning, solutions may have been lost

whenever I try to solve it. Anyone have any ideas? My worksheet is here:  1.mw

Hello,

I have some points that i have plotted thanks to the function pointplot.

Is it possible to add tags next the points (like it is possible in Excel) ?

Of course, I have a vector with the definition of the contents of the tags that I would like to add.

Thanks a lot for your help

Hello,

I cant find solution how to create matrix form from equations of motion. Equations looks like this:

My equations ar much more complicated and one of them looks something like this:

 http://i63.tinypic.com/21c5ctk.png

and I want form like this:

I tried to do it using the Generate Matrix but it does not work as I expected. How can you get this form?

how to convert system of differential equations to differential form for evalDG?

[a(t)*(diff(c(t), t))+b(t), a(t)*(diff(b(t), t))+c(t)*(diff(b(t), t)), a(t)*(diff(c(t), t))+a(t)*(diff(b(t), t))+b(t)];

when i try eliminate dt which is the denominator

eliminate([a(t)*dc(t) + b(t)*dt,a(t)*db(t)+dt*c(t)*db(t),a(t)*dc(t)+a(t)*db(t)+b(t)*dt],dt);

[{dt = -a(t)/c(t)}, {a(t)*(c(t)*dc(t)-b(t)), a(t)*(db(t)*c(t)+c(t)*dc(t)-b(t))}]

i got two solutions, which one is correct?

a(t)*(c(t)*dc(t)-b(t)), a(t)*(db(t)*c(t)+c(t)*dc(t)-b(t))

does it mean that two have to use together to form a differential form?

update1

with(DifferentialGeometry):
DGsetup([a,b,c], M);
X := evalDG({a*(c*D_c-b), a*(D_b*c+c*D_c-b(t))});
Flow(X,t);
Flow(X, t, ode = true);

got error when run with above result

Hey all,

The title is probably very poorly explained and doesn't make much sense at all, but here goes nothing:

I define at the start of my .mw file that M:=1, but I need to be able to change it in order to run multiple different iterations.

So what I've come up with so far is a way to get a variable ammount of equations named "eqc(1,3,5,...)" The number of equations I get is equal to the M defined in the beggining. How would I go about solving this?
To give you an idea of something to work with:

So basically I'd need to solve as many of these eqc equations as I get. If I change M to, lets say 30, I'd need to solve 30 equations. This solve option above doesn't work and I've messed around with Vectors and Matrixes but I honesly have no idea what I'm doing there, so I thought best to seek out help.

Thanks in advance, Rafael.