Reducing space in pgfplots xtick label number format?

Question

With the following MWE:

\documentclass{standalone}
\usepackage{pgfplots}
\usepackage{tikz}
\usetikzlibrary{intersections} %% named intersections
\usetikzlibrary{fit}
\usetikzlibrary{calc}


\begin{document}

\begin{tikzpicture}
\begin{axis}[
  width= 400pt,
  ymin = 0,
  ymax = 5,
  xmin = 0,
  xmax = 7,
  xtick = {0,1,...,7},
  scaled x ticks=real:2324823,
  xtick scale label code/.code={}, % this to not show extra scale label
]

\addplot [] coordinates {(0,0)};

\end{axis}
\end{tikzpicture}

\end{document}

... I'm getting xtick label formatting like this:

I would prefer less spacing between the numbers and the central dot - this is the previous image edited in Gimp to show my preference:

Is this possible to do somehow - maybe through some settings for /pgf/number format/sci?

Answer 1

Based on my comment:

As @HarishKumar notes, reducing the space will give inconsistent results. Scientific notation in the text of your document will not look the same, and in general it's not a good idea to fiddle with TeX's spacing recommendations. The \cdot is spaced out because it is a binary operator.

But if you really need to do it, you may add
[/pgf/number format/sci generic={mantissa sep={\!\cdot\!},exponent={10^{#1}}}]
to the tikzpicture options, as shown in the complete code below.

Alternatively, you can use braces around \cdot to override TeX's default operator spacing:
[/pgf/number format/sci generic={mantissa sep={{{\cdot}}},exponent={10^{#1}}}]
The extra set of braces is required to prevent the keyval system from treating the braces as another nesting level.

You may, of course, further adjust the spacing/kerning commands around the \cdot to your liking.

The code

\documentclass{standalone}
\usepackage{pgfplots}

\begin{document}

% Choose either one of the following two lines
%\begin{tikzpicture}[/pgf/number format/sci generic={mantissa sep={\!\cdot\!},exponent={10^{#1}}}]
\begin{tikzpicture}[/pgf/number format/sci generic={mantissa sep={{{\cdot}}},exponent={10^{#1}}}]
\begin{axis}[
  width= 400pt,
  ymin = 0,
  ymax = 5,
  xmin = 0,
  xmax = 7,
  xtick = {0,1,...,7},
  scaled x ticks=real:2324823,
  xtick scale label code/.code={}, % this to not show extra scale label
]

\addplot [] coordinates {(0,0)};

\end{axis}
\end{tikzpicture}

\end{document}

The output

Answer 2

Well, thanks to these questions:

• What commands are there for horizontal spacing?
• Removing spaces between "words" in math mode
• Labels in xtick with pgfplots

... at least I found a manual way to do it - by manually typing and overriding xticklabels at the end of the axis setup:

...
  xtick scale label code/.code={}, 
  xticklabels={$0$, $4.3{\cdot}\!10^{-7}$, $8.6{\cdot}\!10^{-7}$, $1.29{\cdot}\!10^{-6}$, $1.72{\cdot}\!10^{-6}$, $2.15{\cdot}\!10^{-6}$, $2.58{\cdot}\!10^{-6}$, $3.01{\cdot}\!10^{-6}$ },
]
...

... which results with:

... which doesn't look bad at all - but who wants to type this kind of stuff manually :)

So if there's some automatic way to wrap the \cdot and add a negative math skip \! after it, that would be great to know...