Develop Reference

MPAndroidChart set current visible X axis

Using MPAndroidChart, I'm struggling to figure out how to set the current visible x axis values. The use case is simple and I would have thought very common, so I'm sure I must be missing some function which can do this:
Say you have a chart with x axis values 1-100
A user zooms and pans a chart so that the range 60-80 is visible. I want to store these values, so that tomorrow when the user re-launches the app, I can restore the exact viewing state (60-80)
Storing the values is really easy - you can simply call chart.lowestVisibleX and chart.highestVisibleX to get the x axis values. But how do I set them on a new instance of the chart? Unfortunately there doesn't seem to be a chart.setHighestVisibleX or chart.setLowestVisibleX.
This previous question / answer is nearly, but not quite, what I need. The suggestion is to use a combination of chart.moveViewToX(60) and chart.setVisibleXRangeMaximum(20). However as the docs for setVisibleXRangeMaximum state:
Sets the size of the area (range on the x-axis) that should be maximum
visible at once (no further zooming out allowed)
I don't want to prevent further zooming, which is what this does. There must be a way to set the zoom level without actually restricting further zooming - but I can't figure it out. Any suggestions?
Thanks

Just to answer my own question, I decided to workaround this issue by resetting the X range maximum after calling moveViewToX. This appears to work. So the solution would be:
chart.setVisibleXRangeMaximum(20)
chart.moveViewToX(60)
chart.setVisibleXRangeMaximum(100)

MpAndroidChart: dashed line relating to data count

I need to show chart with dashed line in my application. I am using MpAndroidChart to achieve it. It works, but when data contains too much values, it works incorrectly. For example:
Only 7 values on chart:
Over 500 values:
How to fix it?

The library behaves as expected. The problem is that you are providing too many data points so that the curve overlaps itself (and thus the dashing is displayed as in your image).
Depending on your use case I can suggest the following solutions:
Reduce the line width (probably not sufficient in your case)
Smooth the data points (on this page an overview of possible methods is given)

Make limit line always visible on mpandroidchart

I am making an app which retrieves data from a database and shows it on a barchart. I have defined a limit line using the provided methods at 30f (on the Y axis).
The problem is, that I want that limit line to be always shown and it only becomes visible when one of the Graph's Bars raises above that value (30f).
Is there a way to always show it?
I have tried with the zoom functions with no luck.

Modify the YAxis display range to your needs: https://github.com/PhilJay/MPAndroidChart/wiki/YAxis-(YLabels)
Especially those methods should help:
setAxisMaxValue(float max): Set a custom maximum value for this axis. If set, this value will not be calculated automatically depending on the provided data.
setAxisMinValue(float min): Set a custom minimum value for this axis. If set, this value will not be calculated automatically depending on the provided data.

achartengine time chart set initial range

SOLUTION
Instead of using setInitialRange() I had to set the initial x-values using setXAxisMin() as well as setXAxisMax(). A little bit confusing, I think.
ORIGINAL QUESTION
I'm currently working on a project involving the acharteninge library for drawing time diagrams which works excellent so far. The user is capable of switching between various graphs (one XYMultipleSeriesDataset plus one TimeSeries per graph) via separate buttons. So far, achartengine displays all x values when the graph is shown.
However, I was asked to display only the data captured in the first three hours when the graph is shown, as this information is most relevant. Nevertheless, the user should still be able to scroll to data captured after the first three hours meaning that limiting the x-axis maximum value is not an option.
For example: There are two curves. The first curve is drawn using data captured over a period of 4 hours, while the second curve is created out of data captured over 18 hours.
In the current version my programme initially displays all data of the graph which gets displayed meaning the first curve shows three hours of very relevant data while 1 hour of not so important information is shown too. The "ratio" of the second curve is 3 to 15 (highly significant data vs regular data). As a result, a different amount of high important information is shown when the user compares the two curves making it harder for the user to compare this data, as he has to adjust the zoom manually.
EDIT 01.04.2015 15:46
For setting the initial range I use the XYMultipleSeriesRenderer instance's method setInitialRange(double[] initialRange); which does not affect the graph at all. Below you can see my statement (currentlyProcessedCurve.getRecordStart() is an instance of Joda's DateTime and furhtermore it's the x value of the first displayed point):
public static final int CHART_X_AXIS_INITIAL_MAX = 3;
public static final int CHART_MARGIN_PAN = 45;
...
double[] initialRange = { currentlyProcessedCurve.getRecordStart().minusMinutes(ApplicationSettings.CHART_MARGIN_PAN).toDate().getTime(), currentlyProcessedCurve.getRecordStart().plusHours(ApplicationSettings.CHART_X_AXIS_INITIAL_MAX).toDate().getTime(), 0, 600 };
currentDatasetRenderer.setInitialRange(initialRange);
TIDE (Edit end)
The screenshot below approximately shows how the curve should look initially (Just for making it clear: Please only consider the graphs' shapes, as they should look equal --> What I'm trying to say: I know that the x-axis and the y-axis label of the two screenshots different, but I don't have better pictures yet):
desired initial range
Finally, the following screenshot shows how the curve looks when displayed:
For enabling the user to compare the curves I have locked the y-axis zoom.
Any help is highly appreciated. Thanks in advance!

Have you consider pan option?
With this option you can limit axis maximum, and your chart will show the important data on start, while user can scroll left or right (wherever you have less important data points).
All you need to do is:
set pan enabled for axis you need
set pan limits (so user can't scroll past the last data point)
Hope this helps,
Cheers.

Instead of using XYMultipleSeriesRendererInstance.setInitialRange() I had to set the initial x-values using XYMultipleSeriesRendererInstance.setXAxisMin() as well as XYMultipleSeriesRendererInstance.setXAxisMax().
double xMinValue = ...;
double xMaxValue = ...;
currentDatasetRenderer.setXAxisMin(xMinValue);
currentDatasetRenderer.setXAxisMax(xMaxValue);

Issues faced while drawing dynamic line graph using AChartEngine in Android

How to stop scrolling of AChartEngine dynamic line graph along the y-axis?
When I dynamically plot values I wish to display the recent plotted value. How to do that?
I wish to plot y- axis values in range 20 to 200 and want to display only 5 values so I have used mRenderer.setYLabels(5); But, when I do so grid lines are displayed for only those values. And user will not be able to know the exact y axis co-ordinate. How to show grid lines for each value and show labels for only some values?
If I manually scroll graph horizontally towards right or left, x-axis labels change. I set range as 0-10 with setXLables(2); but it changes to 0,5,10… How to control this behavior?

These should be 4 separate questions, not numbered ones. So, I will only answer the first one of them:
You can set the min and max displayed values:
renderer.setXAxisMin(minValue);
renderer.setXAxisMax(maxValue);
If by scrolling you mean panning, then this is the way to do:
renderer.setPanEnabled(false, false);
renderer.setZoomEnabled(false, false);