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# How do I make a histogram using data from a frequency distribution table?

Posted 10 years ago
 In my maths textbook I already have the frequency distribution table, and I want to create a histogram using that data. And when I'm inputting the data into my histogram, rather than listing each number the amount of times it occurs (e.g.{48,48,49,49,49,49,49,49,49,49,49,49,...,53,53}), is it possible to input something that the histogram would recognise as the frequency of a number (e.g. "50 occurs 32 times", rather than typing 50, 32 times).
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Posted 10 years ago
 The average is just taking each data item times its frequency and adding them all together and then dividing by the total of all the frequencies. So.... In[2]:= dataSpec = {{1, 12}, {3, 4}, {9, 34}, {32, 7}}; In[3]:= data = dataSpec[[All, 1]] Out[3]= {1, 3, 9, 32} In[4]:= frequencies = dataSpec[[All, 2]] Out[4]= {12, 4, 34, 7} In[6]:= Tr[data frequencies]/Tr[frequencies] Out[6]= 554/57 
Posted 10 years ago
 How would I then work out the average using the number set I have just gotten, without having to go in and manually delete all the " { } "
Posted 10 years ago
 Well one hack would be to generate the needed data for the histogram from your specification. So, let's say your spec what you suggested, e.g. {value,nValues}. Then you could recreate the data from this by using ConstantArray on it. Here's an example: dataSpec = {{1, 12}, {3, 4}, {9, 34}, {32, 7}}; histogramData = ConstantArray[#[[1]], #[[2]]] & /@ dataSpec Histogram[histogramData, 40] 
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