I want to format all numbers from 1 to 50 so that they are all 2 digits long.
desiredOutput={01,02,...,49,50}
Digging through the documentation the NumberForm function looked promising.
After trying many options and parameters I so far cannot achieve my desired output.
format = NumberForm[#, 1, NumberPadding -> {"0", ""}] &;
format/@Range[50]
I notice that NumberForm can "adapt" to integers of different lengths for numbers of length 3.
Here is way to do it that also handles negative integers as well as non-negative ones.
Clear[format]
format[n_Integer] /; -1 < n < 10 := NumberForm[n, 0, NumberFormat -> (Row[{"0", #1}] &)]
format[n_Integer] /; -10 < n < 0 := NumberForm[-n, 0, NumberFormat -> (Row[{"-0", #1}] &)]
format[n_Integer] := n
Test
format /@ Range[-12, 12, 2]
{-12, -10, -08, -06, -04, -02, 00, 02, 04, 06, 08, 10, 12}
If[# < 10, "0" <> ToString@#, ToString@#] & /@ Range[50]
or,in your way
If[# < 10, NumberForm[#, 1, NumberPadding -> {"0", ""}], #] & /@ Range[50]
It's not exactly a number formatting, but this might be of some help anyway:
format = StringPadLeft[ToString@#, 2, "0"] &;
format /@ Range[50]
{"01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50"}
Clearly, the Head of the list elements is not NumberForm anymore, but String, which might be useful for some applications (plot ticks for example) but not for others...
g[x_] := If[ 0 < x < 10, NumberForm[x , NumberPadding -> {"0", ""}], x]
g/@ list
in alternative, since my answer is similar to what wuyudi has proposed, you can use patterns with appropriate conditions
Range[50] /.
x_ /; 0 < x < 10 -> NumberForm[x , NumberPadding -> {"0", ""}]
IntegerString[#, 10, 2] &would be somewhat more direct. Note that both of these methods will truncate integers larger than 2 digits. – LegionMammal978 Jan 21 '20 at 00:46