Issues creating error bar for bar figure

Hi,

I'm trying to create error bars on my bar plot.

I get the error: "Input arguments must be numeric, datetime, duration, or categorical."

I'm not sure what I'm doing wrong. Even when I make err equal to two numbers it still doesn't work.

AMean = 656631

AMean = 656631

BMean = 1130

BMean = 1130

ASTD = 237027

ASTD = 237027

BSTD = 209

BSTD = 209

AHeight = 10

AHeight = 10

BHeight = 11

BHeight = 11

Names    = ["A"; "B" ] ;
Averages = [AMean; BMean] ;
StandDev = [ASTD ; BSTD] ;
SampSize = [AHeight; BHeight] ;
NewTable = table(Names, Averages, StandDev, SampSize) ;

x   = NewTable.Names ;
y   = NewTable.Averages ;
err = StandDev ./ sqrt(SampSize) ;

bar(x, y)

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errorbar(x,y,err)

Error using errorbar (line 86)
Input arguments must be numeric, datetime, duration, or categorical.

Answer 1

[Matt J]

Here's an MWE:

x   = ["A"; "B" ] ;
y   = [3,4] ;
err = [0.5,0.75] ;

bar(x, y); hold on
errorbar(categorical(x),y,err,'r', 'Linestyle','none');
axis padded

[Kristine]

I didn't realise it was as simple as forgetting to add "hold on"

[Kristine]

@Matt J Why isn't there a line connecting your two error bars? I have a line connecting mine as seen in CHuguang's example below as well. How do I remove that?

[Chuguang Pan]

@Kristine. In order to remove a line connecting, you can use Linestyle = 'none' as shown in the code:

errorbar(categorical(x),y,err,'r', 'Linestyle','none');

[Matt J]

But it would be very strange to connect the bars with lines. Lines on a plot are meant for visualizing increases and decreases of y with x. But here, there is notion of "increasing x". The x-axis just contains unordered bar labels A and B.

Answer 2

[Chuguang Pan]

The problem lies in the variable Names is string array, which is not supported by errorbar function. You can use categorical function to convert string array to categries.

AMean = 656631;
BMean = 1130;
ASTD = 237027;
BSTD = 209;
AHeight = 10;
BHeight = 11;
Names    = ["A"; "B" ] ;
Averages = [AMean; BMean] ;
StandDev = [ASTD ; BSTD] ;
SampSize = [AHeight; BHeight] ;
NewTable = table(Names, Averages, StandDev, SampSize) ;
x   = NewTable.Names ;
y   = NewTable.Averages ;
err = StandDev ./ sqrt(SampSize) ;
bar(x, y)
hold on
errorbar(categorical(x),y,err)

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