Insert text if column contains a number

I have a tab-delim file that looks like this

10      7.98862e-05
10      cellular organisms; Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Ralstonia; Ralstonia solanacearum  0.000159772
10      0.000207704
10      cellular organisms; Bacteria; Terrabacteria group; Firmicutes; Clostridia; Clostridiales; Clostridiaceae; Clostridium; Clostridium sp. C105KSO15        0.00092668
10      9.58635e-05
10      0.000191727
10      0.000127818
10      cellular organisms; Bacteria; Terrabacteria group; Firmicutes; Clostridia; Clostridiales; Peptostreptococcaceae; Clostridioides; Clostridioides difficile       0.0                                                               0142198
10      cellular organisms; Bacteria; Terrabacteria group; Firmicutes; Clostridia; Clostridiales; Clostridiaceae; Clostridium; Clostridium sp. C105KSO15        0.00268418

It should be three columns but some rows are missing the second column (bacterial taxonomy). For these rows I want to move the number to a third column and insert some text (such as Unclassified).

I have been attempting to modify some commands I found online to insert Unclassifiedt before any value in the second column which starts with a number but have been unable to get it working.

Any help would be much appreciated.

Answer

give this line a try:

awk -F't' -v OFS="t" 'NF==2{$3=$2;$2="Unclassified"}7' file