Loading and formatting data for plotting standard deviation bars on top of data

Question

I have a file with three columns, space separated. First column is x, the second is the data, and the third is the standard deviation I computed of that data.

Now I want to plot in Mathematica, and want the standard deviation on top of the data points.

How do I do that by importing the file ?

Answer 1

data

First I create an analog to your data.

SystemOpen@SetDirectory[$TemporaryDirectory]

Export[
  "Q175948-data.txt",
  Table[
   N@{i, RandomVariate[NormalDistribution[i, Sqrt[i]]], Sqrt[i]}
   , {i, 100}],
  "TSV"
  ];

Solution

Now the answer

One can load the data using

Import["Q175948-data.txt", "TSV"]

Now you need to format it as explained in the documentation for ErrorListPlot

That can be done using ReplaceAll (/.) (many other ways are possible)

data /. {a_, b_, c_} -> {{a, b}, ErrorBar[c]}

Now load the ErrorBarPlots package

Needs["ErrorBarPlots`"]

Here loading formatting and plot all together

ErrorListPlot[
 Evaluate[
  Import[
    "Q175948-data.txt"
    , "TSV"
    ] /. {a_, b_, c_} -> {{a, b}, ErrorBar[c]}
  ]
 , PlotTheme -> "Scientific"
 ]