keywords add floating point number

[FabianL1908]

Hello,
I want to change the linewidth of a plot. I tried using this:
std::map<string,string> keywords; keywords["linewidth"]="0.4"; plot(x,y,keywords)

But then I get the error:

gc.set_linewidth(self._linewidth) TypeError: a float is required

Now I wonder how to add keywords that require a floating point number.

Thanks

[ShipsWithCannons]

Have you tried the following instead?

std::map<string,string> keywords; keywords["linewidth"]=0.4; plot(x,y,keywords)

You were passing a string, not a float.

[FabianL1908]

Yes I tried it. The error stays the same

[FabianL1908]

In fill_between.cpp there seems is no problem with floating point numbers.
std::map<string, string> keywords; keywords["alpha"] = "0.4"; keywords["color"] = "grey"; keywords["hatch"] = "-";

The problem should be in these lines 334-337 in matplotlibcpp.h:
for(std::map<std::string, std::string>::const_iterator it = keywords.begin(); it != keywords.end(); ++it) { PyDict_SetItemString(kwargs, it->first.c_str(), PyString_FromString(it->second.c_str())); }

[propellaone]

You could explicitly check for keywords that demand double values and convert the strings to PyFloats:

for(auto it = keywords.begin(); it != keywords.end(); ++it) {
  if (it->first == "linewidth" || it->first == "markersize")
    PyDict_SetItemString(kwargs, it->first.c_str(), PyFloat_FromDouble(std::stod(it->second)));
  else
    PyDict_SetItemString(kwargs, it->first.c_str(), PyString_FromString(it->second.c_str()));
}

Perhaps, someone could think of a more general way to do that, but it does the job.

[pfeatherstone]

instead of using map<string,string>, use map<string,any>
then we can get clever with types

[mdaley]

Use of map<string, any> - I've tried this locally and it works well. I've been able to modify my 3d surface plot with different colours, transparency, block sizes, for example:

    settings.insert({"alpha", 0.5f});
    settings.insert({"rstride", 5});
    settings.insert({"cstride", 5});
    settings.insert({"cmap", PyObject_GetAttrString(matplotlibcpp::detail::_interpreter::get().s_python_colormap, "gist_rainbow")});

But this requires C++17.

What's the chance of upgrading this project to require C++17?

What would people locked to C++11 do? Could use a separate branch or tag? Personally, I much prefer upgrading so as to get hold of new useful features but I know that not everyone can do that.

[pfeatherstone]

if you use nonstd, you can use C++98 above
https://github.com/martinmoene/any-lite

[pfeatherstone]

Check out the rest of the nonstd libraries. They are awesome if you need backward compatibility with old compiliers:
https://github.com/martinmoene/span-lite
https://github.com/martinmoene/expected-lite
https://github.com/martinmoene/optional-lite
etc